Abstract in English:

ABSTRACT. Water and saline stresses are the main factors affecting agricultural production in semiarid regions. The tolerance of forage cactus to water and salt deficit makes it a promising solution, in particular Nopalea cochenillifera. The growth curves for species facing these conditions can provide useful information supporting the cultivation and management of natural populations and carry significant biological importance as growth rate assessment contributes to maintaining species viability. The objective of this study was to estimate the plant height and linear dimensions (length, width, and thickness) of N. cochenillifera Giant Sweet clone growing under water and saline stress. The experiment design was completely randomized, comprising a 4 × 4 factorial, with four water and four salinity levels; there were four replications. In order to estimate plant height in N. cochenillifera Giant Sweet clone as a function of the accumulated thermal sum, generalized additive models for location, scale, and shape (GAMLSS) were used to determine water level, saline level, length, width, and thickness. We constructed models using four distributions: the Weibull, Gumbel, Logistic, and Box-Cox power exponential distributions. The models were evaluated using global deviation and the generalized Akaike criterion. The Box-Cox power exponential proved to be the most effective in estimating N. cochenillifera height. This model enabled information relevant to practical environmental management to be obtained, as it precisely defined the optimum salt application and the required amount of replacement water, together with the cladode width for each plant growth stage using the accumulated thermal sum.

Abstract in English:

ABSTRACT. Brachiaria brizantha is the most economically important forage grass in Brazil and is propagated through sowing. Producing high-quality seeds has been a constant challenge due to their uneven maturation. The development and application of precise and non-destructive methods for identifying internal damages to seeds, such as the X-ray test, which quickly indicates the quality of the lots, is of fundamental importance for the seed industry. In this work, the quality of Brachiaria brizantha seeds was analyzed based on the morphological characteristics observed in X-ray images that were related to viability using a mixture model under a Bayesian approach, with the following objectives: i) verify the adequacy of the Bayesian modeling used in the data analysis; ii) associate the efficiency of using radiographs as a way to assess the viability of the seeds; and iii) relate the classifications carried out by evaluators with the probability of originating normal or abnormal seedlings. The methodology applied for the analysis proved to be adequate. Further, the Bayesian estimates for parameters related to internal morphology were established with associated levels of uncertainty, which represents an advantage over usual frequentist methods. Based on the model's estimates, seeds evaluated as potentially unviable by three evaluators had practically no probability of germination and did not germinate in the test applied later. Seeds classified as potentially viable had a high probability of developing into normal seedlings, while 73.27% showed this property in the germination test.

Abstract in English:

ABSTRACT. Analysis of variance (ANOVA) is the most used procedure for comparing means between different groups. However, in some cases, disregarding the assumptions of ANOVA can lead to spatial dependence. In such cases, to ensure greater experimental precision, it is necessary to consider the study of spatial dependence. This study was carried out to compare the estimates of experimental precision of the traditional analysis of variance with those of the analysis of variance using an autoregressive (ANOVA-AR) model in corn experiments under different N conditions when evaluating grain yield. Data were obtained from 14 experiments using lattice designs conducted in 2012, 2014, and 2015 in the following counties in the Brazilian state of Mato Grosso do Sul: Caarapó, Dourados, Glória de Dourados, and Laguna Carapã. Of the 14 experiments, 7 were performed with N fertilization (ideal) and 7 experiments were performed under stressful conditions (zero or low). Both analyses were compared by considering estimates of reduction of the error mean square, coefficient of determination, F-value, and selective accuracy as well as the difference in the order of 25% of the genotypes of each experiment (from 13 to 56 genotypes, considering the size of the experiment). Differences in the error mean square and genotype mean square were slightly more evident in 1, 2, 3, 4, 5, 6, and 11 experiments but the use of ANOVA-AR did not promote major changes. The analysis of variance with an autoregressive model provided parameter values of experimental precision similar to those expressed by traditional analysis of variance. There was no difference in terms of correlated errors in experiments under different N conditions.

Abstract in English:

ABSTRACT. Drying is an important step in the post-harvest processes as a way of product conservation and quality preservation. In this context, this study aimed to evaluate the effect of continuous and intermittent drying of maize grains with different rest periods on the integrity of their micro- and macroscopic structures. Maize grains were harvested with a moisture content of 0.3399 ± 0.001 dry basis (db) and subjected to continuous and intermittent drying with 4, 8, 12, and 16 hours of rest period. An experimental fixed-bed dryer, with controlled drying air conditions at a temperature of 100 °C and air flow of 1.5 m3 min.−1 m−2 (12 m3 min.−1 m−3), was used. Continuous drying was completed with a moisture content of 0.1628 ± 0.0003 db, whereas intermittent drying was interrupted with 0.2195 ± 0.0002 db and resumed after rest. The drying rate, integrity through grain images, the conformation of particles through scanning electron microscopy, and cell membrane integrity were evaluated. The drying rate increased with an increase in the rest period, the increase in rest period reduced the intensity of cracks, and the reduction in rest period led to higher dispersion and reduction in the size of starch granules and lower integrity of cell membranes.

Abstract in English:

ABSTRACT. Phytophagous mites can cause economic losses in many crops, including grapevines. The changes in their population levels may be associated with changes in the predator-prey relationship. Knowledge of the distribution of mites in plants is important for planning sampling strategies and facilitating control decisions. The aims of this study were to (i) evaluate the abundances of Tetranychus urticae (Tetranychidae) and Neoseiulus californicus (Phytoseiidae), and the correlations between them and environmental factors; (ii) determine their distribution on the top, middle, or base strata of the evaluated grapevines (Vitis vinifera, Chardonnay cultivar) and, additionally, report the first occurrence of damage caused by T. urticae in grapevine leaves in the state of Rio Grande do Sul, Southern Brazil. Sixteen samplings were conducted, divided between the 2018 and 2019 seasons. In each sampling, three leaves from the three strata of the plant (top, middle, and base) were collected from 20 plants, totaling 60 leaves per sampling. The predator-prey relationship and their association with environmental variables were evaluated with multivariate correlation, whereas the number of mites per plant leaf strata was compared using a generalized linear mixed model in R software. It was possible to observe the symptoms of damage caused by T. urticae attacks on grapevines in Southern Brazil, characterized by the presence of yellow spots and general yellowing of the vineyard. Our findings indicate that T. urticae and N. californicus individuals are strongly associated with each other regardless of the environmental variables, and such relationship occurs mainly on the lower strata (middle and base leaves) of grapevines. Thus, by taking into account the damage on the leaves of grapevines and the occurrence of T. urticae and N. californicus majorities on specific strata of these vineyards, we suggest that the lower strata of grapevines should be the priority targets for management strategies to control such mites.

Abstract in English:

ABSTRACT. The objective of this study was to evaluate the transmissibility of F. verticillioides, in corn seeds, when inoculated in different phenological stages. The plants were inoculated with the pathogen at the following stages: V7, V9, R1, R2, R4, and R6. The experiments were conducted in pots, in a completely randomized design, with six replications. The fungus infection rate in the seeds was verified through the health test (Blotter Test). The significance of the contrast between the phenological stages and in the two experiments (rainy season and dry season), and productivity showed plant-seed transmission of F. verticillioides in all phenological stages. The PCR technique was able to reveal up to the lowest level, 1% incidence of F. verticillioides in corn seeds. There was a significant difference between the times of plant inoculation and the incidence of the fungus in the seeds. Plants inoculated in the reproductive phase transmitted F. verticillioides for seeds with the highest rate of infection, in the two experiments, in the rainy season (V7 - 48; V9 - 46; R1 - 77.33; R2 - 84; R4 - 96; R6 - 96.67; and Test - 14.67%), and dry season (V7 - 46.67; V9 - 66; R1 - 75.33; R2 - 95.33; R4 - 98; and R6 - 97.33%). In this way, the present work demonstrated that in the reproductive phenological stages R2, R4, and R6, the corn plant was more susceptible to infection with F. verticillioides, and that it also resulted in a decrease in grain productivity.

Abstract in English:

ABSTRACT. We investigated aggregation patterns in three fruit fly species economically important in Brazil, namely Ceratitis capitata, Anastrepha fraterculus, and A. obliqua. The study was carried out in a buffer zone and two neighbourhoods by comparing two-time series associated with the management strategy of fruit flies (systems approach). The abundance of these three species significantly decreased over the years with a negative binomial regression model describing the relationship between abundance and time in the entire area, buffer zone, and their neighbourhoods. In addition, the negative binomial model was also well fitted to the frequency distribution data of fruit flies in all analyzed scenarios. Anastrepha obliqua showed the highest aggregation degree, considering both the entire area and time series. A. fraterculus exhibited the lowest aggregation level, and C. capitata showed an intermediate degree. The buffer zone exhibited the highest aggregation degree for all species, and neighbourhood 2 exhibited the lowest aggregation degree. The aggregation degree was higher in the time series impacted by the systems approach than the series in the first years of its implementation.

Abstract in English:

ABSTRACT. Amaranthus palmeri S. Waston is currently one of the most problematic weeds worldwide. Biotypes with resistance to herbicides such as glyphosate and ALS inhibitors are now present in almost all Argentinian cultivable areas. In this work, we studied glyphosate resistance in three different populations, some of them previously characterized as resistant to ALS inhibitors. Dose-response curves were conducted in order to assess the effect of glyphosate on the survival and dry biomass of the populations. Subsequently, the presence of target-site resistance (TSR) was studied. Results confirmed the glyphosate resistance in the three populations, showing different levels of resistance, being R2 and R3 significantly more resistant than r1 population. A high prevalence of the P106S substitution was detected in the three resistant populations, while none increase in the relative EPSPS copy number was noticed. Some surviving plants without any of the TSR mechanisms for glyphosate were detected in R3 population, suggesting the presence of non-target-site resistance (NTSR).

Abstract in English:

ABSTRACT. Chemical control is essential for efficient pest management in coffee crops. Application technologies should safely deliver insecticides to the target whilst protecting the environment, insecticide applicators, and consumers. To achieve these goals, application volumes, hydraulic nozzles, and application techniques should be evaluated. This study assessed the biological efficiency of different spray volumes and spray nozzles used to apply insecticides to control coffee berry borer (Hypothenemus hampei) populations. We applied insecticides using a hydropneumatic sprayer with and without an electrostatic spraying system. The experiment followed a randomized block factorial design (2 × 2 + 1) and included two types of spray nozzles [a hollow cone spray nozzle (JA1) and a hollow cone spray nozzle with air induction (TVI)], two spray volumes (200 and 400 L ha-1), one additional treatment (SPE2 nozzle with a 200 system 200 L ha-1), and six replicates. We assessed the control efficiency of the different application methods by evaluating the percentage of fruits damaged 20 and 40 days after the date of application. The spray volume did not affect the biological efficiency of pest control, and the lower spray volume (200 L ha-1) was effective in the control of coffee berry borers. Application of insecticides using coarse droplets was more efficient than the application using very fine and fine droplets. The TVI hydraulic spray nozzle effectively controlled coffee berry borers at 200 and 400 L ha-1. The electrostatic application system performed similarly to the conventional system in terms of the control of the coffee berry borers, and was less efficient than the conventional system under some operational conditions.

Abstract in English:

ABSTRACT. Several diseases are difficult to control specially in subtropical regions and perennial hosts where the pathogen survive easily within the plant. The aim of this study was to identify which pathogens are surviving after end of one season and at the beginning of the next season to inform which pathogens represent potential risk as primary inoculum to the next season. Survival of pathogens on apple tree twigs was evaluated during dormancy and on beginning of vegetative growth in four orchards located in the two main apple production regions: Palmas and metropolitan region of Curitiba, in Paraná State, Brazil. For this purpose, 10 cm long asymptomatic twigs were collected from 10 randomly selected plants, 24 twigs per plant. Half of the twigs were left directly (without disinfection) in humid chambers for 30 days at 25ºC. The other half of the twigs were disinfected and kept in a freezer for 12 hours at -16ºC by the Over Night Freezing Incubation Technique (Onfit) and then kept in a humid chamber for 30 days at 25ºC. The fungi Colletotrichum sp., Botryosphaeria sp., Alternaria sp., and Fusarium sp. were detected in the two sampled dates and methodologies in all evaluated regions. Neonectria ditissima was only detected in both orchards from Palmas. The genera found surviving on twigs were confirmed molecularly by BLASTn and were pathogenic in wounded fruits from the cultivar ‘Gala’. Our results indicate that pathogens are surviving in orchards after winter treatment and throughout the apple season, being potential sources of inoculum for infections in flowers and fruits, where the pathogens detected cause important diseases as bitter rot, Neonectria fruit rot, white and black rots, and possibly cause Alternaria and Fusarium rots which have not been extensively studied in Brazil.

Abstract in English:

ABSTRACT. Chickpea is a legume with nutrient-rich grains important for human feeding. Tobacco budworm, Chloridea virescens (Lepidoptera: Noctuidae), is one of the most major pests of chickpea (Cicer arietinum) in Brazil. This pest damages leaves, flowers, pods, and grains. Plant resistance to insects is an important tactic of pest management, which usually facilitates and reduce costs of implementing an Integrated Pest Management for farmers. Thus, this study aimed to evaluate the resistance in chickpea cultivars to C. virescens. Six chickpea cultivars were evaluated for antixenosis, initial antibiotic parameters, and behavior under field conditions. The cultivars BRS Kalifa and BRS Cícero were less attractive in a free-choice test, while Jamu 96 and BRS Kalifa were less attractive in a no-choice test. BRS Kalifa and BRS Toro leaves had a higher trichome density. Jamu 96 and BRS Toro had higher contents of oxalic and malic acids. C. virescens larvae in BRS Cícero, BRS Toro, and BRS Kalifa showed the lowest weights. Jamu 96 pods were the least damaged, and BRS Aleppo and Jamu 96 had the highest yields. The chickpea cultivars Jamu 96 and BRS Aleppo, which had resistance levels and mechanisms, can be used in integrated pest management programs to control C. virescens.

Abstract in English:

ABSTRACT. Bacterial leaf streak caused by Xanthomonas vasicola pv. vasculorum is an emerging disease for corn production around the world. However, information on management of this disease is still limited. This study aimed to determine the in vitro sensibility of X. vasicola pv. vasculorum to different chemicals and to evaluate the control of bacterial leaf streak on corn under greenhouse conditions. In vitro tests were carried out with kasugamycin, copper sulfate, copper oxychloride, copper hydroxide, cuprous oxide, bioactive copper, mancozeb, chlorothalonil, methyl thiophanate, and tebuconazole at the dosages of 1, 5, 10, 20, 50, 100, 200, and 400 μg mL−1. Four strains of X. vasicola pv. vasculorum were included in the study. The minimal inhibitory concentration for kasugamycin ranged from 50 to 200 μg mL-1, whereas to the inorganic copper compounds varied from 5 to 50 μg mL-1 and to the bioactive copper was 100 μg mL-1. Further, mancozeb and tebuconazole inhibited the bacterial growth at the dosage ranging from 5 to 20 μg mL-1 and 50 to 400 μg mL-1, respectively, depending on the X. vasicola pv. vasculorum strain. Chlorothalonil and methyl thiophanate did not inhibit the growth of the bacterium at any tested concentration. The control of bacterial leaf streak under greenhouse conditions was investigated on corn plants of the cultivar IPR 164 at the V3 phenological vegetative stage, sprayed with kasugamycin (3 mL L-1), copper oxychloride (1.5 mL L-1), bioactive copper (1 mL L-1), mancozeb (2 g L-1), tebuconazole (1 mL L-1), and chlorothalonil (2 mL L-1). The corn plants were inoculated with a 108 CFU mL-1 suspension of the RL1 strain of X. vasicola pv. vasculorum. Only copper oxychloride significantly reduced disease severity. However, this copper compound caused phytotoxicity to the corn plants at the tested concentration.

Abstract in English:

ABSTRACT. Grain size is an essential trait in common bean breeding as it determines the acceptance of a new cultivar by producers, consumers, and the industry. The objectives of this study were to identify the ideal traits for selecting common bean lines in the F3 generation to obtain an adequate sieve yield and to identify the best lines for sieve yield by applying early generation selection. Two trials were conducted in two locations during the 2016/2017 crop season. These trials were composed of 300 F3 populations and two parents (used as checks). The experimental design used was an augmented block design without repetition for the treatments (lineages). After harvest, the grain yield, yield components, and sieve yield (SY) were evaluated. In conclusion, selection in the F3 generation can be performed for sieve yield, considering the traits SY12+13, SY14, and relative grain yield, as they present the highest values of heritability and greatest correlation between genotype and performance in the evaluated environments. Additionally, the lines selected to continue in the breeding program are composed of the 15 best lineages for traits SY12+13, SY14, and relative grain yield. Preference should be given to lines that excel in more than one of these traits.

Abstract in English:

ABSTRACT. An enhanced level of drought tolerance in wheat (Triticum spp.) may be reached through combining agronomic and physiological traits associated with grain yield under drought conditions. We aimed to explore valuable diversity for the drought tolerance, existed in the core collection of Iranian spring bread wheat landraces. A number of 206 spring bread wheat accessions along with the check cultivar were assessed for grain yield, drought-adaptive traits, and estimated drought tolerance criteria during 2016-17 and 2017-18 growing seasons. Analysis of data using the best linear unbiased predictions (BLUPs) approach revealed that the genotype x environment (GE) interactions accounted for the highest variation in grain yield (36.23%) followed by 1000-kernel weight (35.39%), heading date (21.4%), days to maturity (16.38%), and plant height (5.83%). Using the hierarchical cluster analysis and developed pattern heat map based on the values for the agronomic traits and drought resistance indices, the accessions clustered into nine groups of different sets of agronomic and drought tolerance characteristics. Several accessions with high yield potential, early heading, optimal plant stature and high drought tolerance groups were identified. Three drought selection criteria of stress tolerance index (STI), geometric mean productivity (GMP) and mean productivity (MP) were more effective in identifying accessions producing higher yield under both drought and irrigated conditions. The superior accessions identified in this study may be explored further for breeding new wheat cultivars with enhanced level of drought tolerance.

Abstract in English:

ABSTRACT. In cotton crops, the cotton seed yield significantly contributes with the success of any cultivar. However, other traits are considered when an ideotype is pointed out in the selection, such as the fiber quality traits. The aim of this study was to applied genotype by yield*trait (GYT) biplot to a multi-environment trial data of cotton genotypes and selected the best genotypes. For this end, thirteen genotypes from nineteen trials were assessed. Seven traits were evaluated [cotton seed yield (SY), fiber percentage (FP), fiber length (FL), fiber uniformity (FU), short fiber index (SFI), fiber strength (FS), and elongation (EL)] and residual error variances structures [identity variance (IDV) and diagonal (Diag)] were tested by bayesian information criterion. After, the REML/BLUP approach was applied to predict the genetic values of each trait and the selective accuracy were measured from the prediction. Then, the GYT-biplot were applied to the data. For SP and SFI traits, the model with Diag residual variance was indicated, whereas for SY FL, FU, FS, and EL traits the model with IDV residual variance demonstrated the best fit to the data. Values of accuracy were higher than 0.9 for all traits analyzed. In the GYT-biplot acute angles were find for all traits relations, which means high correlation between the yield*traits combination. Besides that, the correlation still can be seen in the GYT-biplot, as shown by the magnitudes of the angles between the pairs Yield*FU-Yield*FS and Yield*FS-Yield*EL. Also, the GYT-biplot indicates the genotype G4 with the best performance for Yield*FS, Yield*SFI, Yield*FU, Yield*FL, and Yield*FP combined. The genotypes G4, G1, G13, G8, and G9 represent those genotypes with yield advantage over the other cultivars. Then, the genotype G4 combines all desirable characteristics and demonstrate have large potential in the cotton breeding. The GYT approach were valuable and were highly recommended in cotton breeding programs for selection purpose in a multivariate scenario.

Abstract in English:

ABSTRACT. Evaluation of combined ability can eliminate lines that are inefficient and enable the subsequent program steps to be more successful. The objective of this study was to predict the general (gi) and specific (sij) combination ability of popcorn S1 progenies for early selection. A total of 288 topcrosses were performed under a randomized complete block design with two replicates at two sites (Campinas and Capão Bonito, São Paulo State, Brazil). Diallel analyses were performed using mixed models and the maximum likelihood restricted/best unbiased linear prediction method. Evaluated traits included grain yield (GY; kg ha-1), weight of 100 grains (g), and popping expansion (PE; mL g-1). Ear components were also evaluated, including ear length, ear diameter (cm), and the number of grain rows (unit). The S1 progeny 32 presented the highest gi for GY in Campinas, whereas progeny 46 presented the highest gi for GY in Capão Bonito. The S1 progeny, 114 was an important parent for the popcorn breeding program, because it presented high gi for the traits of agronomic interest at both sites. Combination 86×IAC12 exhibited a high sij, and the 86 parent presented the second-highest gi for PE in Campinas, and it should be used for high PE genotypes.

Abstract in English:

ABSTRACT. In Brazil, there is an increasing demand for common bean (Phaseolus vulgaris L.) cultivars having Carioca-type (cream-colored seed coat with brown stripes) beans which have a light color that persists for a longer time combined with the most possible upright plant architecture. However, plant breeders are finding it difficult to combine these two traits in the same cultivar. The aim of this study was to compare success in the selection of new common bean lines that combine the two traits in segregating populations with 25%, 50%, or 75% of the alleles from the parents contrasting in upright plant architecture or in bean grains with persistent light color. A biparental cross was performed between a parent with light-colored beans (P1) and another with upright plants (P2). Three populations were obtained from the F1 seeds, with allelic frequencies of 75%, 50%, and 25% of P1. Subsequently, progenies were evaluated in a similar number in each population in the F2:3, F2:4, F2:5, and F2:6 generations. The plant architecture (PA) and grain darkening (GD) traits were visually evaluated using a scoring scale. Genetic and phenotypic parameters were estimated for all generations. There was no expressive advantage in using populations with a greater allele proportion of the parent favorable to upright plant architecture or slow grain darkening either in releasing of variability or in the occurrence of progenies with favorable phenotypes for the two traits.

Abstract in English:

ABSTRACT. The cultivation of special corns, such as baby corn, has had a positive influence on the economy of the country. Despite its importance, there is still a need for studies aimed at increasing production and planting areas of the crop. Phytosanitary studies are of particular interest, as the cultivation of such crops is susceptible to a series of pathogens, such as Bipolaris maydis, Exserohilum turcicum, and Puccinia polysora. The use of resistant cultivars is the most effective way to prevent the occurrence of these diseases. Thus, the present study aimed to identify popcorn lines that have the potential for baby corn production and are resistant to the main leaf diseases that affect the crop. The experiment was conducted in randomized blocks with four replications of 30 lines in each area, during two planting seasons. The area was located at the Federal Institute of Espírito Santo (IFES) Campus of Alegre, situated in Rive district, Espírito Santo State, Brazil. Using the obtained data, the area under the disease progress curve was obtained. Subsequently, analysis of the joint variance of the data was conducted, and when a significant effect was found, a grouping of means test was conducted. The Mahalanobis distance for each pair of lines was also calculated, and the genetic distance matrix was used to construct a dendrogram using the UPGMA method. Considering the averages obtained for the three diseases (Southern corn leaf blight, Northern corn leaf blight, and Southern rust), lines L61, L63, L65, L683, L684, L685, L691, L694, and L695 were identified as possible donors of resistance alleles for multiple diseases. Multivariate analysis efficiently grouped the lines L61, L63, L684, L685, and L691, which are described as most resistant in the univariate analysis.

Abstract in English:

ABSTRACT. To be considered drought-tolerant, a tomato cultivar is required to present some level of tolerance at all developmental stages of plant growth. Since drought tolerance is a stage-specific phenomenon, genotype assessment must be performed separately at all developmental stages. In this study, we used a multi-trait index based on factor analysis and genotype-ideotype distance (FAI-BLUP index) to properly rank 49 tomato genotypes according to their tolerance to drought stress conditions at germination and seedling stages. Seeds of 47 introgression lines, which cultivar M82 is considered drought-sensitive, and the Solanum pennellii wild accession LA 716, which is considered drought-tolerant, were subjected to a control condition, where seeds were soaked in distilled water, and a drought condition, where seeds were soaked in a polyethylene glycol (PEG) solution (-0.3 MPa). Drought stress, induced by PEG, had a significant impact on all nine germination and growth performance-related traits; there was a reduction in shoot length (SL), total length (TL), initial germination percentage (IGP), final germination percentage (FGP), germination velocity index (GVI), and germination rate (GR). In contrast, the root-to-shoot ratio (R/S) and time to reach 50% germination (T50) increased under drought stress. Root length (RL) was less affected by drought, and in some genotypes, it was even increased. As expected, LA 716 ranked closest to the drought tolerance ideotype. IL 1-4-18, IL 2-3, IL 1-2, IL 9-2, and IL 10-1 were the most drought-tolerant at the germination stage. These results will serve as guidance for breeders who are aiming at developing drought-resistant tomato cultivars.

Abstract in English:

ABSTRACT. The study of promoters has become essential to elucidate genetic regulation and allow new genetic transformation strategies through plant biotechnology. The challenge is to discover and validate promoters that can regulate gene transcription spatially and/or temporally. The goal of this work was to validate genes associated with tissue-specific promoters of bananas obtained from in silico sequences and selected from the DATAMusa databank. Gene expression was quantified using RT-qPCR from different tissues: leaves, flowers, roots, unripe pulp, ripe pulp, unripe peels, and ripe peels of two different genetic groups: Prata-Anã (PA; group AAB) and Grand Naine (GN; group AAA). After the analysis of the expression of genes associated with the promoters, normalization was performed with the most stable reference genes (TUB and L2) selected using the RefFinder tool. It was determined that five genes were specific or expressed to a greater extent in some tissues than others. The EMB-23 gene was highly expressed in ripe pulp and flowers of GN, EMB-26 in the ripe pulp of GN, EMB-27 in flowers of GN, EMB-28 in roots of PA and ripe pulp and roots of GN, and EMB-31 in roots and flowers of GN and PA, and unripe pulp of GN. The in silico analysis was efficient in the identification of spatial/time-specific genes, thereby decreasing analysis time and cost, making future genetic transformation studies focusing on the application of these tissue-specific promoters possible.

Abstract in English:

ABSTRACT. Sweetpotato (Ipomoea batatas L.) is an important tuber vegetable for human health worldwide owing to its nutritional value and productivity. Consumption of orange-fleshed sweetpotato is beneficial to combat vitamin A deficiency in the world, including Brazil, as these tubers are rich in β-carotene, a precursor of vitamin A. The genotype × environment interaction is one of the greatest challenges in plant breeding, specifically in the selection and approval of cultivars. In this context, adaptability and stability analyses are warranted to evaluate the performance of various genotypes in terms of general or specific adaptations to certain environments and to identify genotypes responsive to environmental variations. Thus, the objective of this study was to evaluate the genotype × environment interaction as well as to estimate the adaptability and stability of sweetpotato genotypes for identifying and selecting promising candidates for breeding. The experiments were performed in four environments: Vera Cruz in São Paulo, Selvíria in Mato Grosso do Sul, and one organic and another intercropped production system in Sete Barras in São Paulo. A randomized block design with two replicates was adopted. A total of 265 genotypes were tested, and the orange-fleshed sweetpotato cultivar ‘Beauregard’ was used as the control. The additive main effects and multiplicative interaction model was used to study environmental stratification, adaptability, and stability. The genotype × environment interaction was evident in all environments. The genotypes CERAT21-13 (marketable root yield, 22.30 t ha-1 in the four environments), CERAT29-26 (27.74 t ha-1), and CERAT52-22 (20.24 t ha-1) were the most adapted in general to the four environments. CERAT25-23, CERAT29-23, and CERAT29-26 were the most adapted to the environment in Vera Cruz; CERAT29-26, CERAT34-14, and CERAT56-32 to the environment in Selvíria; and CERAT31-10, CERAT35-19, and CERAT52-22 to the two environments in Sete Barras.

Abstract in English:

ABSTRACT. Fig tree (Ficus carica L., Moraceae), which originated in the Mediterranean Basin, is one of the many fruit trees grown in Brazil, with ‘Roxo-de-Valinhos’ being the exclusively used cultivar. In this context, research aimed at the improvement of this species to develop highly resistant and adaptable cultivars is paramount. Thus, the present study aimed to maintain fig accessions in an in vivo active germplasm bank (AGB) at the Faculty of Engineering of Ilha Solteira (FEIS), São Paulo State University (UNESP), as well as to characterize the agronomic traits of these accessions based on quantitative descriptors of genetic parameters and observe gains with the selection of specific genotypes to illustrate the AGB in terms of genetic variability. A total of 36 F. carica genotypes were evaluated in the field at the Teaching, Research and Extension Farm (FEPE) of the FEIS, UNESP. Qualitative traits, fruit parameters (e.g., insertion of the first fruit, fruit stalk length, fruit length, fruit diameter, and average fruit mass), and accumulated plant dry mass were measured. In addition, genetic parameters, variance components, and descriptive statistics, including genetic and environmental variances, heritability and average heritability of clones, coefficients of genotypic and environmental variation and their ratio (CV g %/Cv e %), general average, and selection gain, were evaluated. The selected fig tree accessions showed genetic variability in the assessed traits, exhibiting good heritability and achieving selection gains. For instance, the first 10 classified clones exhibited a heritability of 80.2% and achieved a selection gain of 98% for accumulated plant dry mass. Therefore, the maintenance of in vivo AGBs allows agronomic studies, offering promising results for continuing the breeding programs and preserving the genetic variability of species.

Abstract in English:

ABSTRACT. The BRSMG Uai common bean cultivar (Phaseolus vulgaris L.) unites traits required by producers, such as high yield and upright stands, the latter of which is considerably improved in relation to previously released cultivars such as BRSMG Madrepérola and Pérola. However, the potential of the cultivar to form symbiotic relationships with rhizobia to fix N2 has not yet been assessed. Here, field experiments were conducted to assess the efficiency of biological nitrogen fixation (BNF) in the cultivar, and to compare this to the efficiencies of other genetic materials widely grown throughout Brazil (BRSMG Madrepérola and Pérola). Experiments were conducted on two Oxisols in Minas Gerais State, Brazil (one during the dry season in the south, and the other during the winter season in the Alto-Paranaíba region), under a no-tillage system over maize stover. A randomized block experimental design was implemented in a 3 × 3 factorial arrangement with four replicates. Individual and combined Analysis of Variance were performed and the data were normalized. Homogeneity of the residual mean squares was observed. Significant effects of factors were identified by Scott-Knott tests and F tests. The BRSMG Uai cultivar responded to inoculation with the rhizobial strain CIAT 899, with yields similar to those achieved upon fertilization with 80 kg ha-1 of N-urea and to the yields of the BRSMG Madrepérola and Pérola cultivars inoculated with the same rhizobial strain. In terms of commercial use, this cultivar may be successful under either of the management practices adopted for N supply, and from the perspective of plant breeding, it has potential for inclusion in breeding programs directed toward improving BNF.

Abstract in English:

ABSTRACT. Yacon is a perennial herbaceous plant that naturally occurs in South America at altitudes ranging from 2,000 m to 3,100 m above sea level. The yacon culture has recently grown in popularity as it has high productive potential in mild climates and multiple benefits to human health. This study aimed to determine the lower and upper base temperatures, cycle duration, and thermal constant for the yacon culture, based on phenological data from field experiments that were carried out during three growing seasons (fall, winter, and spring) in 2013. The experiments were conducted in the municipality of Ibatiba in the state of Espírito Santo, Brazil, in a randomized block design with four replicates. The lower base temperature was determined using methods of the lowest standard deviation in days and degree-days, relative development, and variation coefficient in degree-days for two subperiods: emergence to maturation, and onset of tuberization to maturation. The upper base temperature was determined by the standard deviation and coefficient of variation methods, both in degrees-days. The relationship between meteorological elements and the onset of tuberization was also investigated. The lower base temperature values determined for yacon were 12.5ºC in the two subperiods studied with a base temperature above 34.0ºC. The productivity of these tuberous roots was higher in the fall because of the longer cycle, lower temperature, and lower photoperiod. In turn, a higher thermal sum was needed to initiate tuberization with the delay of planting.

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ABSTRACT. Apple tree has been experimentally grown Brazilian tropical semiarid. In these new regions, fertilizing management research for N and K is crucial to reach apple high yields. Therefore, an experiment was conducted to evaluate the effect of N and K fertilizing on fruit production, leaf chlorophyll and N and K nutritional status of apple cv. ‘Julieta’ grown in Brazilian tropical semiarid. The experimental design used was randomized blocks with treatments disposed in a factorial arrangement (4 x 4) referring to nitrogen doses (30, 60, 90, and 120 g of N plant-1) and potassium doses (30, 60, 90, and 120 g of K2O plant-1), with three replications and three plants in each parcel. ‘Julieta’ apple trees propagated by grafting (with ‘M9 filter and Maruba rootstock) and transplanted in 2013 were used in this study. The following variables were evaluated: i) fruit production (kg plant-1); ii) number of fruits (in a plant); iii) leaf chlorophyll index (‘a’, ‘b’, and total); and iv) leaf N and K concentrations (g kg-1). N and K doses effects depend on the consecutive production cycles of apple cv. ‘Julieta’ grown in tropical semiarid. An adequate N supply is very important for the subsequent production cycle. K fertilization until 120 g plant-1 of K2O is not enough to supply K demand of apple cv. ‘Julieta’ grown in tropical semiarid. In tropical semiarid, 60-90 g plant-1 of N through fertirrigation is enough for ‘Julieta’ apple production.

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ABSTRACT. The objective was to evaluate the forage yield and structural responses of spineless cactus ‘Orelha de Elefante Mexicana’ (OEM) (Opuntia stricta (Haw.) Haw) at different planting densities. The experimental design was a randomized block with five treatments and four replicates, during two production cycles of 12 months each. The evaluated densities were 20,000; 25,000; 33,333; 50,000; and 100,000 plants ha-1. The increase in planting density caused a linear reduction in plant height, width, and mass, as well as in number of primary, secondary, tertiary, and overall cladodes. It also caused a linear increase in cladode area index, dry and green yield, water use efficiency, and forage accumulation rate. The increase in planting density promoted a quadratic effect on cladode thickness and dry matter content. Cladode thickness decreased with planting densities up to 47,500 plants ha-1 and increased from this point onwards. As for dry matter content, there was an increase up to the planting density of 61,428 plants ha-1 and a decrease from this point onwards. The increase in planting density of spineless cactus ‘Orelha de Elefante Mexicana’ caused changes in structural responses and in forage yield. The use of greater planting densities increased forage yield.

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ABSTRACT. The objective of this study was to evaluate the the ability of foliar application of potassium nitrate (KNO3) to induce water deficit tolerance in sorghum plants (Sorghum bicolor cv. P898012) subjected to water deficit at pre-flowering. The experiment was conducted under greenhouse conditions with 4 treatments: field capacity (FC), water deficit (WD), field capacity + KNO3 (FC + KNO3), and water deficit + KNO3 (WD + KNO3). Two foliar applications of 3% (m/v) KNO3 were made, the first on day zero of stress and the second on the fifth day. All analyses were performed after 12 days of stress (end of stress). Foliar application of KNO3 to irrigated plants led to increases in relative chlorophyll content, photosynthetic rate, stomatal conductance, transpiration, and carboxylation efficiency. It also induced increases in leaf concentrations of P, Mg, S, Cu, and Fe, in addition to height growth. Under water deficit conditions, plants treated with KNO3 presented higher relative chlorophyll content, leaf area, photosynthetic rate, stomatal conductance, transpiration, carboxylation efficiency, and higher levels of P, K, Mg, S, Cu, and Fe than those not treated with KNO3. The morphometry of the root system was not altered by the treatments. In addition, plants treated with KNO3 under water deficit conditions showed higher growth and a grain yield 32.2% higher than those that did not receive KNO3. These results demonstrated that KNO3 applied to the leaves induced water deficit tolerance in sorghum plants subjected to severe water stress at pre-flowering.

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ABSTRACT. Seed coat characteristics may be related to seed quality and longevity, attracting the interest of breeding programs. This study aimed to evaluate the relationship between the water absorption parameters and storage tolerance of soybean seeds with contrasting seed coat characteristics. For this purpose, seeds of five soybean cultivars with different seed coat colors and lignin contents were used. Before storage, the seed coat lignin content, moisture content, water absorption rate in 11 hydration periods (1, 2, 3, 4, 5, 6, 7, 8, 24, 32, and 48 hours), hydration speed index, germination, viability, and seed vigor were determined. After six months of storage in a dry and cold chamber (at 11ºC and 54% relative humidity [RH]) and uncontrolled environment (at 25ºC and 71% RH), the seeds were evaluated for germination, viability, and vigor to quantify changes in their physiological quality during storage and relate them to the seeds water absorption parameters for the different cultivars. The seed coat lignin content is negatively correlated with the seeds water absorption parameters. Soybean cultivars have different storage tolerance levels. Seeds that absorb larger amounts of water have lower tolerance to deterioration related to temperature and relative humidity fluctuations that occur in storage under uncontrolled conditions, negatively affecting the physiological potential of seeds.

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ABSTRACT. This study evaluated the effects of fertigation, banana biomass as a soil covering under drip and micro-sprinkler irrigation system on the root growth and distribution and their relations with chemical soil attributes, soil water availability, and productivity. This work was conducted in a field with banana 2.5 × 2.0 m spacing and irrigated every two days using a drip and micro-sprinkler irrigation system during the first crop cycle. The experiment followed a random block design with six treatments, two irrigation systems, two fertilization methods of fertigation and side-dressing, as well as two cultivation types with and without soil covering. Roots were collected from each plot using soil monoliths and digitalization allowed the determination of root length density, and diameter at several distances from the plant and at different soil depths. Total root length, density, and distribution by diameter were evaluated based on the treatment interactions with respect to the distance from the plant and the soil depth. Our results showed that the combination of the irrigation system, fertilizer application and soil covering influenced root growth and distribution. In addition, we found that the better soil conditions for root growth were in drip or micro-sprinkler systems with fertigation and cultivated biomass covering.

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ABSTRACT. Rock dusts in association with organic sources have been used in agriculture to improve soil chemical characteristics and food composition. In this context, this study aimed to evaluate the effect of the rock dusts siltstone, tephrite, and olivine melilitite pure or combined and associated or not with cattle manure on the chemical composition of soybean seeds of the cultivar BRS 232 grown on a Cambisol and Nitisol subjected to these treatments and conventional fertilization. For this, an experiment was carried out with pots in a greenhouse using a Cambisol and Nitisol to cultivate the soybean from January to May 2019 until seed production. The seeds were harvested, ground, and sieved through a 1 mm mesh sieve to determine the nutrient, phytate, and crude protein contents. The effects of the rock dusts on the chemical composition of seeds were directly related to the chemical characteristics of the evaluated soils. The tested rock dusts had a more pronounced response in the Cambisol (poorer soil) than in the Nitisol (more fertile). The contents and accumulation of nutrients in the seeds, as well as the total dry matter production in both soils subjected to the treatments with the rock dusts olivine melilitite and siltstone + olivine melilitite, pure and combined with manure, were similar and, in some cases, higher than the treatments subjected to conventional fertilization. The combination of manure and rock dusts provided an increase in the concentration of nutrients in both soils, resulting in their higher availability for plants and directly reflecting on the chemical composition of seeds.

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ABSTRACT. Seed reserve mobilization is considered a post-germination process; however, seed storage protein mobilization occurs during germination. Thus, the knowledge of seed protein composition is important to understand various processes during germination, and it be associated with seed vigor. Therefore, this study aimed to characterize landrace genotypes of common bean (Phaseolus vulgaris) through fractionation of seed storage proteins during germination and to verify the association between seed protein composition and seed vigor. Genotypes of the highest (55 and 81) and lowest (23 and 50) physiological quality were selected. Protein content analysis, profiling, and characterization were performed by combining different hydration times. Mass spectrometry involving in-gel digestion and MALDI-ToF analysis was employed for the qualitative identification of proteins. Glutelin extraction detected the enzyme lipoxygenase in genotypes 55 and 81 alone. In plants, this enzyme may be involved in diverse physiological processes, including growth and development, pest resistance, senescence, and response to wounding. In the process of germination, lipoxygenase removes reactive oxygen species during reserve mobilization; therefore, lipoxygenase may be a candidate biochemical marker for high-vigor genotypes.

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ABSTRACT. Cowpea (Vigna unguiculata) crops produce a poor yield in northeastern Brazil compared to the other regions. The goal of this study was to assess the effects of irrigated cropping systems and sowing seasons on cowpea yield and profitability in Vitória da Conquista, Bahia, Brazil. Field studies were performed in four experiments during the rainy and dry seasons during 2016/2017 and 2017/2018, which denoted harvests 1, 2, 3, and 4, respectively. A randomized block design was used for each experiment with four replicates and the following treatments for cropping systems: (1) manual weeding; (2) liming and manual weeding; (3) liming and phosphorus (P) fertilization at sowing, nitrogen (N) and potassium (K) topdressing fertilization, and chemical weed control; (4) liming and P fertilization at sowing, K topdressing fertilization, rhizobia inoculation, and chemical weed control; (5) liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control; and (6) seed pretreatment with cobalt (Co) and molybdenum (Mo), liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control. The technology added to cropping systems increased the number of pods per plant, pod length, seeds per pod, and 100-seed weight, irrespective of the rainy or dry sowing season. Economic analysis, in turn, showed that the technology decreased the total operating cost despite increasing the cost of mechanical operations, inputs, and materials because of the replacement of manual weeding by chemical weed control. However, these costs were not influenced by the sowing seasons. We concluded that technologically enhanced cropping systems, especially systems 4 and 6, improved grain yield and provided greater profitability, which translated into improved economic benefits for farmers. Conversely, the sowing season influenced profitability, which was higher for dry season harvests, when there was less product offered and prices became higher.

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ABSTRACT. The intergovernmental panel on climate change predicts a progressive increase in atmospheric CO2 concentration and temperature; however, their effects on cereals have been shown for a limited number of species. This study evaluates the effects of increased CO2 concentration and temperature separately and combined on millet growth and grain production in open-top chambers where the microclimate was adjusted to the following conditions: ambient CO2 and temperature; CO2 enriched (~ 800 ppm) and ambient temperature; ambient CO2 and higher temperature (+3ºC); and CO2-enriched and higher temperature. For each treatment, two chambers were used, each containing 15 7 L pots. Each pot received five seeds at the beginning of the experiment and thinning to one plant per pot at 15 days after sowing. Ten plants were harvested from each chamber 65 days after sowing and the plant height, the number of leaves and the longest root length as well as shoot and root biomass were measured. The remaining plants were harvested 130 days after sowing to evaluate grain production. The results indicate that high CO2 levels did not affect plant growth and biomass. On the other hand, plants subjected to high temperature grew 7% taller than those grown under ambient temperature. Contrastingly, plants submitted to both elevated CO2 and temperature were 19% taller and had 22% more shoot biomass than plants under ambient CO2 and temperature. However, grain production did not change in any of the environmental conditions. We provide evidence that millets are tolerant of the predicted climate changes and that grain production potential may not be affected.

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ABSTRACT. Soybean represents a valuable source of food for humans and animals and the quality of the seeds has great importance for the establishment and high productivity of this crop. Soybean seeds require continuous improvement, which is dependent on a better understanding of the regulatory mechanisms that coordinate seed germination. To investigate whether the method of water absorption into soybean seeds could lead to abnormal seedlings, and if this could be associated with cytogenetical consequences, we premoistened the seeds of three cultivars; M 6410 IPRO, M6210 IPRO, and BMX Potência RR by direct immersion (fast method), use of a wet substrate (intermediate method), and by moist atmosphere (slow method) with distilled water at 25ºC for 24 hours. We investigated the normal and abnormal seedlings, electrical conductivity, mitosis, cell death, and the chromosomal abnormalities index. The comet assay was applied to investigate DNA fragmentation. Direct immersion in water induced seedling growth inhibition and caused cytological alterations associated with genotoxicity effects in the studied soybean genotypes. Slow premoistening of the seeds increased seedling performance as a result of higher final germination percentage (above 85%), reduced abnormal seedlings (below 5%, on average), and reduced the electrical conductivity of seeds. All three genotypes of soybean seeds lost their ability to withstand the imbibitional damage induced by direct immersion as abnormal seedlings increased. We concluded that the fast water absorption by seeds poses a threat to genomic integrity owing to its potential for genotoxicity to DNA, manifesting as breaks or loss of whole chromosomes. Slow premoistening of the seeds resulted in a longer time period to deal with damage. Stabilized seedling growth was provided by altering cytogenetic responses during uptake of water by soybean seeds through the maintenance of cell viability.

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ABSTRACT. Signal grass (Urochloa decumbens) and guinea grass (Megathyrsus maximus) are African grasses that are well established in the Brazilian Savannah and we tested their adaptation to different light intensity. Plants were grown for 45 days under 0% shade (full sun) and 25, 40, and 80% induced shade to evaluate their photosynthetic performance. Light curves showed higher values of electron transport rate, photochemical quenching, and effective quantum yield in plants subjected to 0 and 25% shade for signal grass and in 25 and 40% shade for guinea grass. The potential quantum yield evaluations revealed that signal grass felt the effects of excessive light around 11:30 am on plants subjected to 0 and 25% shade. Conversely, guinea grass showed these photoinhibition effects at the same shade level but in a longer time range (9:30 am to 1:30 pm). As shade increased, there was a reduction tendency of the pigment content in signal grass and the opposite was observed for guinea grass. Stomatal conductance showed different values during the day and among different shade levels and there were no differences in relative water content between treatments and species. Results indicated better photosynthetic performance for signal grass under high intensity and better photosynthetic performance for guinea grass subjected to intermediate and higher levels of shade. Altogether, the results indicate that guinea grass seems to be a more appropriate choice for silvopasture systems.

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ABSTRACT. Current literature is lacking regarding the vegetative propagation of the cambuci tree (Campomanesia phaea O. Berg Landrum). This study aimed to verify the efficiency of cutting techniques via the assessment of cuttings of varying types and sizes, sampling dates, and the influence of treatments containing plant growth regulator indolebutyric acid (IBA) combined with the antioxidant ascorbic acid across different immersion times. The species was found not to develop adventitious roots easily, and hence, the herbaceous and woody stem materials were subjected to histochemical studies to elucidate their anatomical and physiological processes. To this end, plant material was polymerized in glycol methacrylate resin, cut into sections, and stained using toluidine blue (0.05%) or via histochemical staining with PAS/naphthol blue black. Anatomical analysis of plant structures revealed the presence of phenolic compounds and sclerenchyma tissue, which in turn are expected to negatively impact the development of adventitious roots.

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ABSTRACT. In Brazil, although there is a growing demand for physalis in the food industries, information on the nutritional management of the crop is still incipient. This study aimed to evaluate the biomass production and accumulation of nutrients in the shoots and fruit of physalis in two cultivation sites. Two field experiments were conducted, one where the soil was Typic Quartzipsamment in the municipality of Diamantina and the other where the soil was Rhodic Hapludox in the municipality of São João Evangelista, Minas Gerais State, Brazil. The experiments were conducted in a randomized complete block design with four replicates. The treatments were the evaluation period. Samples were collected every 15 days the day of planting of the seedlings in the field for a period of 240 days. Dry matter and nutrient accumulation in shoot and fruit were evaluated. The biomass production and nutrient accumulation were higher in the edaphoclimatic conditions at São João Evangelista compared to the conditions at Diamantina. Macronutrient accumulation was in the following order: N > K > Ca > S > Mg > P in shoot and N > K > P > S > Ca > Mg in fruit. Micronutrient accumulation in shoot and fruit was in the following order: Fe > Mn > Zn > B > Cu.

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ABSTRACT. Sorghum (Sorghum bicolor) is highly sensitive to zinc deficiency in soils, which results in decreased productivity and low-quality agricultural products. Our objective was to evaluate the effects of different zinc doses, applied to seeds, on the physiological quality and initial performance of sorghum plants. Six doses (0, 3.5, 7.0, 14.0, 21.0, and 28.0 g kg-1 seeds) were used and an uncoated control. The Zn coating process used dolomitic limestone as the filler and glue. Laboratory tests were conducted in a completely randomized design and greenhouse experiments were conducted in a randomized block design. The control means were 8, 9, and 14% lower than the maximum, minimum, and total seed area of treatments, respectively, relative to that of treatments. The control differed from other treatments by 10.47 in the speed index of emergence. Zinc at a dose of 28 g kg-1 seeds provided greater production of aerial dry matter, with nutrient content of 75.85 mg kg-1. Zinc on sorghum seeds affected length and dry matter production of aerial parts and roots but did not affect physical characteristics, germination, or emergence time. Applied zinc accumulated mainly in the roots, and promotes changes in Ca and Mg in seeds and other plant parts.

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ABSTRACT. Coffee outturn can be defined as the ratio between the harvested coffee and its respective processed grains. This character is greatly influenced by genotypic and environmental effects, and in breeding programs your analysis is costly and time-consuming. In this sense, the use of an outturn index to estimate coffee yield on experimental plots is a desirable measure aiming at reducing resources and time in postharvest evaluations. Thus, the present study aimed to evaluate the accuracy of the use of an outturn index equal to 4.0, in the estimation of Conilon coffee grains production. This index indicates that four kilograms of harvested fruit would be needed to obtain one kilogram of processed grains. Based on the average of 157 genotypes conducted in three trials and four harvests, we evaluated the relationship between harvested fruits and processed grains (FcBe), the observed (OGY), and the estimated grain yield per plant (EGY) based on FcBe equal to 4.0 (an outturn index). Descriptive statistics, adequation test for EGY, and the coincidence of occurrence of genotypes observations relating to the top 20% of all observations of OGY and EGY. In the estimation of grain yield in Conilon, the use of FcBe equal to 4.0 showed high precision in the average of the analyzed trials. However, further studies should be conducted to elucidate the effects of climate variables on the yield of Conilon coffee, especially in atypical crop years. Thus, the use of an outturn index becomes interesting in cases where the number of genotypes to be evaluated is very large and a screening of the promising ones is desirable.

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ABSTRACT. Improvements in the traditional production system of peach seedlings, with a focus on the use of selected rootstocks, tend to minimize some of the problems experienced with this crop in the south of Brazil, such as the scarcity of vigorous nursery plants and the lack of a genetic identity for commercial rootstocks. The aim of this study was to investigate the different patterns of nutrient absorption and allocation related to the rootstock in ‘BRS Rubimel’ peach plants by analyzing growth variables during the post-graft period. The experimental design consisted of randomized blocks in a 3 × 3 factorial scheme, with three peach rootstock varieties (i.e., ‘Flordaguard’, ‘Capdeboscq’, and ‘Okinawa Roxo’) and three post-graft evaluation periods (i.e., 30, 60, and 90 days after the start of budding), corresponding to a total of nine treatments, with three replications, each including five plants. During the three evaluation periods, morphological growth characteristics were measured, and the macronutrient content was determined in the different plant organs (i.e., leaf, stem, and roots). The nutrient content in plants of the ‘BRS Rubimel’ peach plants was influenced by the rootstock. Despite showing greater N use efficiency, ‘Capdeboscq’ accumulated a large part of this nutrient in the roots, using it for root growth, which resulted in a smaller scion diameter compared to that of ‘Flordaguard’. Comparing the three rootstocks and the evaluated variables, it seems that ‘Flordaguard’ can be used as a rootstock for the ‘BRS Rubimel’ peach plants, as it induces a greater scion diameter as well as the uniform allocation of dry matter between organs during the post-graft period, hence ensuring greater initial plant vigor.

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ABSTRACT. Water and salt stress conditions affect germination and seedling emergence. It is known that physiological priming can not only trigger different mechanisms to increase the speed and uniformity of germination, but also influence the antioxidant defence system of the seeds, especially in adverse conditions. In this context, the objective of this work was to evaluate the physiological seed quality and the activity of antioxidant enzymes in seeds of Petroselinum crispum induced to tolerate saline stress through osmo-priming. Seeds were placed in polyethylene glycol solutions with three osmotic potentials (-0.5, -1.0 or -1.5 MPa) for 2, 4 or 6 days. Subsequently, they were placed on substrates moistened with sodium chloride solution (NaCl), in concentrations that generated osmotic potentials of -0.2, -0.4, -0.6, -0.8 or -1.0 MPa, to germinate. The germination percentage, germination speed index, seedling length, fresh weight, dry weight and activity of the antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were evaluated. Germination and germination speed index decreased linearly with the increase in NaCl concentrations, indicating the species sensitivity. As for length, fresh weight and dry weight of seedlings, this effect was more expressive from the potential of -0.4 MPa. The vigour and activity of SOD, POD, and CAT enzymes were reduced in unprimed seeds, emphasising the effectiveness of the technique. The induction of tolerance to saline stress can be related to the activity of the antioxidant system observed in seeds.

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ABSTRACT. One way to reduce mineral fertilizers is to use alternative fertilizers instead, such as the byproducts from the food industry. In the present study we evaluated the effects of sugarcane bagasse ash on the physiology, growth, and development of sunflowers (Helianthus annuus L.). We conducted an experiment in a greenhouse using a completely randomized design with two sunflower cultivars (Multissol and Catissol), five sugarcane bagasse ash doses (0.0, 3.125, 4.687, 6.25, and 7.812 mg ha-1), and 5 replicates. At 85 days after planting we determined the plant height; leaf number; stem diameter; internal and external diameter of the flower chapter; leaf area index; shoot dry weight; net assimilation rate; dry mass production rate; relative and absolute growth rate; extravasation of electrolytes; relative water content; photosynthetic pigments (chlorophyll a, b, carotenoids, and the chlorophyll a/b ratio); and soluble carbohydrates, proteins, and proline. The height, number of leaves, and shoot dry mass increased due to the availability of nutrients contained in the ash. The incorporation of ash into the soil increased the photosynthetic activity (chlorophyll a and b) of both sunflower cultivars. The diameter of the stem, leaf area index, and relative growth rate of both sunflower cultivars increased with increasing ash dose. Therefore, the ash can be used as an alternative fertilizer, complementing or replacing mineral fertilizers.

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ABSTRACT. The succession of soybean/maize has been largely adopted. Storm damage and crop problems can lead to grain loss, generating maize ear fragments or even whole ears that remain in the soil and still display germination viability, resulting in the occurrence of volunteer plants. In this context, the present study aimed to evaluate the interference of voluntary maize plants on soybean and investigate the susceptibility of maize hybrids to pre-emergence herbicides. In the first step, an experiment was performed evaluating the influence of voluntary maize plant density and spatial distribution on soybean. The experiment was performed in a randomized completely block design (RCBD) with four replications, with treatments disposed in factorial arrangement (2 x 4) + 1. The first factor corresponded to the spatial distribution of maize plants: row or in between soybean rows; while the second factor adopted four infestation densities of maize plants m-2: 4, 8, 12, and 16. The additional treatment consisted of a control without maize plants. For the second step, an experiment was conducted in two locations aiming to determine the efficacy of pre-emergence herbicides in the control of voluntary maize. Both experiments were installed in RCBD in a split-plot scheme with four replications. Fomesafen, lactofen, sulfentrazone, chlorimuron-ethyl, diclosulam, flumetsulam, imazethapyr, clomazone, metribuzin, [sulfentrazone + diuron], [imazethapyr + flumioxazin], and a control without herbicide application were evaluated in the main plot. In each subplot, the maize hybrids DKB310 PRO3™ and DKB390 PRO3™ were evaluated. No influence on the position of voluntary maize on the soybean yield was observed. The presence of the maize population led to a progressive decrease in soybean yield, ranging up to 86%, at 16 plants m-2. DKB390 displayed a stand reduction of 82.88% after the use of diclosulam. Diclosulam led to better results regarding maize plant decreases for both hybrids.

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ABSTRACT. Precrops have different growth patterns, nitrogen (N) requirements, and production of residues varying in amounts and quality that may affect the N-clycling and the soybean (Glycine max L. Merrill) cropped in succession. This study aimed to evaluate the effect of precrops and N fertilization on soybean performance. An experiment was conducted in Londrina, Paraná State, Brazil, with six precrops treatments: fallow, ruzigrass (Urochloa ruziziensis), showy rattlebox (Crotalaria spectabilis), corn (Zea mays) without or with 80 kg ha−1 of N at topdressing as urea, and wheat (Triticum aestivum). Subplots consisted of two levels of N fertilization at soybean sowing: 0 and 30 kg ha−1 of N as ammonium nitrate at sowing. Urochloa ruziziensis as precrops increased the soybean yield (5,171 kg ha-1) when compared with corn (4,346 kg ha-1) and fallow (4,467 kg ha-1). In 2016/17, N fertilization of soybean with 30 kg ha−1 of N at sowing, although increasing the initial plant growth (745 kg ha-1 with vs. 662 kg ha-1 without), impairs nodulation (100 mg pl-1 with vs. 130 g pl-1 without) and does not increase grain yield. Oil and protein concentrations in soybean grains are not influenced by precrops and N fertilization at sowing. We found that the use Urochloa ruziziensis as cover crop in soybean precrops is a good recommendation option in tropical regions of Brazil, because increasing the yield of soybean grown in succession. N fertilization at in soybean sowing it should not be recommended even in the presence of a large amount of straw.

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ABSTRACT. Leaf area is one of the most commonly used physiological parameters in plant growth analysis because it facilitates the interpretation of factors associated with yield. The different leaf formats related to soybean genotypes can influence the quality of the model fit for the estimation of leaf area. Direct leaf area measurement is difficult and inaccurate, requires expensive equipment, and is labor intensive. This study developed methodologies to estimate soybean leaf area using neural networks and considering different leaf shapes. A field experiment was carried out from February to July 2017. Data were collected from thirty-six cultivars separated into three groups according to the leaf shape. Multilayer perceptrons were developed using 300 leaves per group, of which 70% were used for training and 30% for validation. The most important morphological measures were also tested with Garson’s method. The artificial neural networks were efficient in estimating the soybean leaf area, with coefficients of determination close to 0.90. The left leaflet width and right leaflet length are sufficient to estimate the leaf area. Network 4, trained with leaves from all groups, was the most general and suitable for the prediction of soybean leaf area.

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ABSTRACT. The management of weeds in melon is hindered by the slow initial growth of the crop, favouring weed infestation and reducing production. During the years 2016 and 2017, weed interference periods were evaluated in two melon hybrids, yellow and frog skin, to determine the time of weed control in the crop. Four-parameter logistic regression was used to determine the critical weed control period (CPWC). The weed species with the highest occurrences in 2016 were Merremia aegyptia, Senna obtusifolia, and Urochloa plantaginea. In 2017, there was a predominance of M. aegyptia, indicating the possibility of successive cultivation, favouring the predominance of species with growth habits similar to melons. The increase in the period of living with weeds reduced the productivity and quality of melon fruits. Coexistence with weeds throughout the cycle reduced productivity by about 50%. The CPWC was 15 to 58 and 10 to 45 for frog skin and 12 to 52 and 4 to 50 days for yellow melon in 2016 and 2017, respectively, considering a productivity loss of 5%. These results underscore the importance of adopting strategies that allow melons to grow free from the presence of weeds, especially before they are fully established in the growing area.

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ABSTRACT. Organic agriculture systems have the nutrients supplied by plant or animal by-products, bioinoculants, and compost-based products as earthworm composts and green manures. However, the quantitative and qualitative parameters of soil amendments depend on their sources, and soil amendments are generally not sufficient to supply the nutritional requirements of maize crops. Moreover, specialty maize requires high levels of N. Thus, the aim of this study was to investigate specialty maize varieties supplied with two microbial inoculants applied in two inoculation methods. These factorial treatments were compared with their checks (varieties without inoculation), and the interaction among these factors was also investigated. The trials were carried out during the growing season in 2017-2018 in the State University of Maringá. The popcorn trial followed the randomized complete block design where the factorial 3 × 2 × 2 + 3 had five replications. The trial with white grits maize followed the same experimental design but the factorial scheme was 2 × 2 × 2 + 2 with three replications. Both trials had maize varieties and two species of microbial inoculants (Azospirillum brasilense and Methylobacterium sp.) applied in two inoculation methods, in the seeds and the foliar spray at V4 stage of plant development. The response traits were grain yield and the components of crop production. In both trials, we verified that the majority of the interactions among the factors was non-significant (p > 0.05), indicating the independence of these factors. Furthermore, the microbial inoculants had no beneficial effects on the traits. The possibility of a higher crop yield did not confirm the application of the inoculant in the stage V4. The organic compost may be the key point in mitigating the treatments with microbial inoculants due to the availability of N in the first stages of plant development. The traits also suggest the necessity of more trials about the influence of microbial inoculants on specialty maize production.

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ABSTRACT. One of the great challenges of the beet and cowpea cultivation in crop association is to maintain their productivity as that of their sole counterparts in semi-arid environment. In this context, the objective of this work is to assess whether there is bio-agroeconomic return in associations of beet-cowpea by the optimization of population densities and spatial arrangements of the component crops. Experiments were performed in randomised complete block designs with treatments arranged in a 4 × 3 factorial scheme, with four replications. The first factor was the population densities of cowpea (100, 80, 60, and 40% of the recommended population in single crop - RPSC) in association with beet, and the second factor was the spatial arrangements (2:2, 3:3, and 4:4), formed by beet (B) rows alternating with cowpea (C) rows. The competition and agronomic indices evaluated were aggressiveness, competitive ratio, land equivalent ratio, actual yield loss, intercropping advantage and the productive efficiency index. The economic indicators evaluated were gross income, net income, rate of return and profit margin. High agro-economic efficiency can be obtained in the cultivation of beet and cowpea intercropping when well-managing the factors of production, population densities and spatial arrangement of the component crops. The greatest agro-economic return of the cowpea and beet intercropping was obtained in the population densities of 40 and 100% of RPSC for cowpea and beet, respectively. The 2:2 spatial arrangement between beet and cowpea crops was the one with the best productive performance and higher indicators of economic return. The cowpea was the dominant crop while the beet was dominated.

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ABSTRACT. The use of a protected environment for vegetable seedling production has become one of the best alternatives to minimize the adverse micrometeorological effects of the external environment and guarantee quality and production throughout the year. Inside the protected environment, it is essential to study the physiological responses of plants to the wavelength, periodicity, intensity, and direction of light in the photosynthetic process. Thus, the aim of this study was to investigate the effect of different intensities of photosynthetically active radiation (PAR) used as an extended photoperiod in a greenhouse on the production of basil seedlings. A completely randomized design, in a 2 × 4 factorial scheme, with four replications of 20 seedlings per plot was used. Two basil varieties, sweet basil (green color) and purple basil (purple color), were evaluated under three intensities of supplementary PAR, which were 375, 411, and 438 µmol m-2 s-1, and control, in the absence of supplementary PAR. The seedling height, stem diameter, shoot dry matter, root dry matter, total dry matter, leaf area, ratio between plant height and stem diameter, ratio between plant height and shoot dry matter, ratio between shoot dry matter and root dry matter, and Dickson quality index were evaluated. Results show that higher intensities of PAR used as an extended photoperiod favor the quality of basil seedlings produced in a protected environment.

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ABSTRACT. Excoriation damage is among the major causes of postharvest potato losses. Curing is known to increase the resistance of tubers to excoriation injury, with the temperature influencing the traumatic phellogen and periderm regeneration, as well as tuber processing quality. This study aimed to evaluate the effects of excoriation procedure and curing temperature on the industrial quality, histological characteristics, carbohydrate metabolism, and oxidative enzyme activity of potato tuber. Tubers with or without excoriation were cured at 8, 14, and 20°C for 15 days. Excoriation did not influence the levels of reducing sugars (RS), as well as polyphenoloxidase (PPO) and peroxidase (POD) activities. The concentrations of total soluble sugars (TSS) and non-reducing sugars (NRS) were higher in injured tubers, while reduction in curing temperature increased the concentrations of TSS, NRS, and RS. However, the sugar content was adequate as per the criteria of the pre-fried potato industry and potatoes classified in category 2 (USDA/fast-food industry color grading). The reduction in curing temperature also increased the activity of POD, despite the activity of PPO remaining unchanged. Formation of a closure layer from the outer parenchyma cells of the tuber that prevents desiccation and death of superficial cells, was observed. This protection was completed with the formation of the damage periderm. Periderm regeneration is faster at higher temperatures, 15 and 20°C, leading to a lower fresh mass loss and no enzymatic or non-enzymatic browning. The excoriation carried out at 14/20oC for 15 days was sufficient for curing, and for maintaining suitable post-fry quality of potatoes.

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ABSTRACT. Water deficiency reduces leaf expansion and photosynthetic efficiency, potentially reducing the ability to withstand leaf area (LA) loss. This study aimed to evaluate the effects of water restriction on soybean tolerance to defoliation in the vegetative and reproductive periods of development. Two experiments were conducted in a greenhouse located in Lages, Santa Catarina State Brazil, during the 2017/2018 growing season. Cultivar NA 5909 RG was subjected to three WR levels (none, moderate, and severe) and five defoliation levels (0, 17, 33, 50, and 67%). Defoliation occurred at the V6 stage in the first experiment and R3 in the second. WR occurred for 7 days after defoliation. LA at R2 and R5 after defoliation at V6 and R3 decreased by 27.5 and 64.6%, respectively, regardless of WR. LA between V6 and R2 was not influenced by WR or defoliation. Moderate or severe WR reduced plant ability to recover LA between R3 and R5. Severe WR decreased grain production by 22.2% in the vegetative period and 21.2% per plant in the reproductive period compared to that of the control, regardless of defoliation. The highest defoliation level reduced grain production per plant by 24.7 and 24.3% relative to the control at stages V6 and R3, respectively, regardless of WR. WR imposed at the vegetative and reproductive stages did not increase defoliation sensitivity.

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ABSTRACT. Salinity is one of the environmental stresses that most cause losses in agricultural systems, including tomato production. Brassinosteroids, such as epibrassinolide (EBL), have multiple actions in essential processes in plants. Thus, the objective of this study was to evaluate the contributions of EBL to the growth, physiology, and production of tomato plants under salinity. The experiment was conducted in a factorial scheme, with five levels of water salinity (0.5 [the control], 1.5, 3.0, 4.5, and 6.0 dS m-1) and two concentrations of EBL (0 and 10-6 M). Salt stress reduced tomato growth, relative water content, membrane integrity, gas exchange, and fruit production. However, the exogenous application of EBL attenuated the adverse effects, partially improving these characteristics at all salinity levels. EBL reduced electrolyte leakage and increased membrane integrity and relative water content in control and stressed plants. Additionally, it increased the content of photosynthetic pigments, stomatal conductance, transpiration, and photosynthesis, which led to higher leaf dry mass production, fruit transverse diameter, and production per plant. Therefore, our results confirmed that foliar application of EBL improved the characteristics of stressed and non-stressed tomato plants.

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ABSTRACT. Ex vitro strawberry plantlets from micropropagation and coinoculated with arbuscular mycorrhizal fungi (AMF) and biochar can provide beneficial health effects. In the present study, we evaluated the effects of different proportions of biochar in the presence and absence of AMF on the production of secondary metabolites in the leaves and roots of strawberry plantlets during ex vitro acclimatization. Additionally, the enzymatic activity of the substrate enriched with AMF and biochar was analyzed. The experiment consisted of the control (absence of the mycorrhizal community) and four biochar proportions (0, 3, 6, and 9% of the volume of the container) coinoculated with AMF. Plantlets produced on substrates enriched with AMF showed higher levels of polyphenols, flavonoids, phenolic acids, and tannins in the tissues analyzed than control plantlets. The combination of AMF and 9% biochar increased the content of total flavonoids in the leaves of strawberry plantlets and increased the activity of phosphatase. The substrate with up to 6% biochar and mycorrhizae showed increased β-glucosidase activity. In conclusion, mycorrhizae are excellent tools to improve the phytochemical quality of strawberry plantlets acclimatized ex vitro. The association between host plants, mycorrhizal symbionts, and bioactivators of these fungi potentiates properties beneficial to health, which can be exploited efficiently in sustainable agriculture.

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ABSTRACT. Intensive weed management is one of the most common practices in coffee cultivation areas. Consequently, some problems, such as soil degradation and the selection of herbicide resistant weed, have increased over time, but, if properly managed, weeds at coffee planting inter-rows can offer benefits of erosion control, nutrient recycling and crop sustainability. The aim of this study is to evaluate the effect of different weed management strategies on the productivity and coffee grain size, i.e., quality. The experiment is installed onto a resprouting Coffea arabica L. site, four years after it was established. Treatments are implanted at planting inter-row Urochloa ruziziensis, Pueraria phaseoloides, and spontaneous vegetation maintained by mowing, herbicides, and weeding. To measure dry matter accumulation, samples are taken with a 0.25 m2 square template at plots maintained by mowing and herbicide application. To evaluate the yield and granulometry, coffee fruits are harvested, processed and classified in a set of 14 sieves (grouped in flat or “moca” shapes). The methods of controlling herbicide and weeding show significance in relation to grain production, with the production of grains having a higher market value standing out, when compared with the other treatments. The accumulation of dry matter above soil, in treatments with herbicides and spontaneous vegetation positively influenced the early coffee productivity (2018), and with U. ruziziensis and spontaneous vegetation, positively influenced the productivity of late harvest (2019). The accumulation of dry matter on the soil tends to be positively linked to coffee productivity, especially in periods when there is a shortage of rain in the region under study; however, it cannot be stated that this influence relationship (causality) has a direct positive effect between dry matter mass production and productivity of future coffee plantations.

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ABSTRACT. Many important crops have cultivars with different ploidy and provide a diverse choice of materials for breeding programs. Therefore, it is essential to accurately assess the ploidy of all breeding materials. Increased DNA content is known to have various effects on external and internal morphology, an effect known as the “nucleotypic effect”. Thus, anatomical assessment can be used as a tool for determining ploidy in plants, making the chromosome counting technique or flow cytometry unnecessary. This study aimed to evaluate the leaf anatomical characteristics of banana cultivars and understand the relationship between these features and ploidy levels. Thirteen accessions were evaluated, including diploid, triploid, and tetraploid genotypes, and cultivars, resulting from in vitro propagation after 90 days of acclimatization. Five fully expanded young leaves were collected from each cultivar, fixed in FAA70 (formaldehyde-acetic acid-ethanol) and preserved in 70% alcohol. Transverse and paradermal sections of the abaxial and adaxial regions were taken, and variables such as size and stomatal density, leaf thickness in the midrib and fourth vascular bundle region, and thickness of the epidermis, hypodermis, and parenchyma were measured. Results for leaf thickness, stomatal size, and density proved to be appropriate parameters for characterizing banana ploidy levels.

Abstract in English:

ABSTRACT. The forage palm is widely cultivated in semiarid regions. It has a basic chromosome number of x = 11 and polyploids are the main variation. It is propagated via vegetative reproduction, and sexual propagation is rarely used. The objective was to associate the physiological quality of seeds of different cultivars of forage palm with the level of ploidy in the genera Opuntia and Nopalea. The cultivars used were: diploids (2n = 22) ‘F8’, ‘F21’, and ‘IPA Sertânia’; tetraploids (2n = 44) ‘Clone 6 African Elephant Ear’, ‘Mexican Elephant Ear’, and ‘V19’, and octaploids (2n = 88) ‘Round’, ‘Giant’, and ‘IPA Clone 20’. Thousand seed weight, length, diameter, number of seeds per fruit, first count and emergence percentage, shoot and root length, fresh and dry mass, electrical conductivity, and length, width, and fresh and dry weight of cladodes were measured. A nested scheme design was used, with three levels of ploidy and three cultivars within each level. The ploidy level positively influenced the number of seeds per fruit and the physiological quality of the seeds. Cultivars behave differently within the same ploidy level.

Abstract in English:

ABSTRACT. In various parts of the world, agricultural exploitation faces saline soil or water, such that cultivable species tend to be limited regarding the establishment of seedlings, with effects on productivity. The objective of this study was to evaluate the effects of salinity levels associated with different temperatures on the germination, initial development, and oxidative damage indicators of purple corn seedlings. The experiment was completely randomized in a 5 × 2 factorial design (moistening of the germination paper with 0, 25, 50, 75, and 100 mM NaCl solutions at temperatures of 25 and 30°C). The parameters evaluated were germination, growth, and oxidative damage indicators at the seedling phase. The germinative decline and initial development of purple corn seedlings, regardless of the temperature (25 and 30°C), reflected oxidative damage resulting from saline stress. Although deleterious effects of salinity were observed, a temperature of 30°C provided greater length and accumulation of dry mass of purple corn seedlings compared to the effects at 25°C. Total chlorophyll, chlorophyll a, chlorophyll b, total carotenoids, and lipid peroxidation, regardless of the temperature (25 and 30°C), were identified as sensitive biochemical indicators for the detection of physiological quality of purple corn seedlings subjected to NaCl.

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ABSTRACT. The fungus Monilinia fructicola, which causes brown rot in fruits, is one of the main peach pathogens. The emergence of fungicide-resistant fungus isolates, as well as the attempt to reduce sprays, favors adoption of other control strategies. Among them, one of the most important is genetic resistance. This study was carried out aiming to evaluate the susceptibility of 16 peach and 4 nectarine genotypes to brown rot, as well as to evaluate how well the sporulation area and diameter correlate with number of spores in the lesions. Both wounded and non-wounded fruits were inoculated with 10 μL of M. fructicola suspension. Wounded fruits from all genotypes (nectarines and peaches) showed susceptibility to M. fructicola, from 92 to 100% of incidence. The disease incidence was between 18 and 100% when non-wounded fruits were inoculated. High variability was detected for the fungus sporulation, in both wounded and non-wounded fruits, with ranges between 16 to 96% and 0 to 94%, respectively. The fungus sporulation was variable among the genotypes (between 0.1 to 96.0 conidia per mm2) and it is positively correlated with the diameter and area of sporulation. The genotypes Conserva 947, Conserva 1662, Conserva 672, Conserva 1600, and 'Bolinha', are the ones with less susceptible to brown rot.

Abstract in English:

ABSTRACT. Soil use and management systems modify phosphorus (P) dynamics by changing the different P compartments. However, the interaction between land-use change and altitude is not clear. This study aimed to evaluate the effect of land use on P forms in different soil aggregate classes of Ultisols located at two altitudes. Soil samples were collected in four land-use systems (agroforestry system, secondary forest, pasture, and eucalyptus) located at two altitudes in the Atlantic Forest biome, Brazil. Phosphorus fractions were assessed using sequential fractionation. In general, recalcitrant forms represented about 70% in the agroforestry system, 66% in the eucalyptus, 65% in the pasture, and 57% in the secondary forest relative to the total P content of all land uses at both altitudes. The soil aggregate classes of smaller diameter presented higher P contents in all fractions. The smallest soil aggregate classes showed up to 65% more P than the classes with smaller diameters in the different land-use systems and altitudes.

Abstract in English:

ABSTRACT. Phosphorus (P) is one of the most important elements used in fertilizing soils in tropical regions due to the low efficiency of phosphate fertilization. This work aimed to fractionate inorganic P (Pi) in tropical soils of different mineralogical compositions and to relate these fractions with their respective phosphate buffer capacity (PBC) indicators. The soils were characterized physically, chemically and mineralogically. Additionally, we evaluated the P concentration that remained in solution of soil after equilibrium was met; this was termed P remaining (P-rem). In general, the Pi fractions of soils did not correlate with the PBC indicators. The P-H2O fraction showed a negative correlation with the P-Al fraction. Ferric minerals did not influence P fixation. P-rem showed a strong correlation with the maximum P adsorption capacity, adsorption energy, and the amorphous and crystalline forms of Fe. The minerals of aluminum contributed the most to P fixation. P-rem was the best estimator of PBC. The soils with high, moderate and low rates of P fixation showed high amounts of the fractions P-Al, P-Ca, and P-Fe, respectively. The results showed that P fixation was influenced by the fractions of P in the soil, suggesting that the efficiency of phosphate fertilizers in tropical soils depends on the mineralogy of the clay fraction within those soils.