Resumo em Inglês:

ABSTRACT. The forage palm is one of the main forages of ruminants in semiarid regions. Measurements of leaf area are required in agronomic studies because they are one of the main parameters used to evaluate plant growth. The objective of this study was to validate and define the best models for estimating the area and weight of Giant Sweet clone (Nopalea cochenillifera) forage cladodes in a non-destructive way based on the linear dimensions of length, width and thickness. There were 432 randomly measured cladodes at 550 days after planting. The length, width and thickness of each cladode were measured using a digital calliper. The cladodes were weighed individually. The cladode area was calculated by the gravimetric method. The power regression model was the most efficient method to explain the cladode area as a function of the product of length by width, while the gamma model was the most efficient method to explain the weight of cladodes as a function of the product of length by width and thickness. The power model, RCÂ=LW0.982, and gamma model, WĈ=0.536T+0.028LW, were used to determine the area and weight of Nopalea cochenillifera Giant Sweet clone cladodes, respectively, based on the values of linear dimensions measured independently of the order of the cladode.

Resumo em Inglês:

ABSTRACT. Strawberry is an economically and socially important crop in several regions worldwide. Thus, studies that provide information on topics in strawberry growth are important and must be constantly updated. The aims of this study were to fit a logistic growth model to describe strawberry fruit production and to estimate the partial derivatives of the fitted model in order to estimate and interpret the critical points, in addition to using multivariate analyses. To do this, data on 16 treatments [combinations of two cultivars (Albion and Camarosa), two origins (national and imported), and four mixed organic substrates (70% crushed sugar cane residue + 30% organic compost, 70% crushed sugar cane residue + 30% commercial substrate, 70% burnt rice husk + 30% organic compost, and 70% burnt rice husk + 30% commercial substrate)] conducted in a randomized complete block design (RCBD) with four replicates were used. A logistic model was fitted to the accumulated fruit production stratified by treatment and replication. Partial derivatives related to the accumulated thermal sum were estimated in order to quantify the critical points of the model. Subsequently, a principal component analysis was performed. The results show that the use of growth models substantially increases the inferences that can be made about crop growth, and the multivariate analysis summarizes this information, simplifying its interpretation. Approaches such as those carried out in this study are still rarely used, but, compared to simpler models, they increase the amount of inferences that can be made and provide greater elucidation of the results.

Resumo em Inglês:

ABSTRACT. Spatial data (e.g., phytopathogenic data) do not always meet assumptions such as stationarity, isotropy and Gaussian distribution, thereby requiring complex spatial methods and models. Some deterministic assumption-free methods such as the inverse distance weighting can also be applied to predict spatial data, but their output is limited for graphical solutions (mapping). We adapted a computer-based prediction method called Circular Variable Radius Moving Window (CVRMW) that is based on two others: moving window kriging (MWK) and inverse squared-distance weighting (ISDW). The algorithm is developed to meet an objective function that minimizes the index of variation of the spatial observations inside the moving window. A code in R language is presented and thoroughly described. The outputs include the range of the spatial dependence as the radius calculated at every target location and the standard error of the predicted values, mapped to provide a useful tool for spatial exploratory analysis. The method does not make any assumptions about the spatial process, and it is an alternative for dealing with spatial heterogeneity.

Resumo em Inglês:

ABSTRACT Combining longitudinal data and statistical models from perennial crops enabled us to estimate the optimum number of measures (harvests), implying accurate discrimination of superior genotypes in those crops. Herein, the goal of this study was to determine the optimum number of harvests based on yield traits and recommend a superior graft/rootstock combination (GRC) for Citrus latifolia Tanaka. Twenty-four GRCs of 'Tahiti' acid lime were evaluated from July 2017 to August 2018 for fruit yield per plant (FYP), number of fruits per plant (NFP), and longitudinal (LFD) and transversal fruit diameter (TFD). The experimental design was a randomized complete block with 4 replications. The experimental unit consisted of three individuals, totalling 244 individuals. The GRCs were composed of (i) two hybrids that were used as rootstock, citrumelo ‘Swingle’ (Citrus paradisi x Poncirus trifoliata) and cintrandarin ‘Riverside’ (Citrus sunki x Poncirus trifoliata); and (ii) 12 different C. latifolia genotypes that were used as grafts: Bello Fruit, Eledio, Iconha, Itarana, Santa Rosa, Bearss lime, CNPMF 01, CNPMF 02, CNPMF 2001, CNPMF 5059, BRS Passos, and Persian 58. Mixed models were employed to estimate the variance components. The optimum number of harvests was determined based on selective efficiency values above 0.9. The estimated repeatability coefficients presented values of 0.14 (LFD), 0.16 (TFD), 0.36 (FYP), and 0.38 (NFD). Based on the results, four harvests were able to choose genotypes based on FYP and NFP, whereas LFD and TFD were considered inefficient traits for recommending superior GRCs.

Resumo em Inglês:

ABSTRACT Accurate forest biomass estimates require the selection of appropriate models of individual trees. Thus, two properties are required in tree biomass modeling: (1) additivity of biomass components and (2) estimator efficiency. This study aimed to develop a system of equations to estimate young eucalyptus aboveground biomass and guarantee additivity and estimator efficiency. Aboveground eucalyptus biomass models were calibrated using four methods: generalized least squares (GLS), weighted least squares (WLS), seemingly unrelated regression (SUR), and weighted seemingly unrelated regression (WSUR). The approaches were compared with regard to performance, additivity, and estimator efficiency. The methods did not differ with regard to the mean biomass estimation; therefore, their performance was similar. The GLS and WLS approaches did not satisfy the additivity principle, as the sum of the biomass components was not equal to total biomass. However, this was not observed with the SUR and WSUR approaches. With regard to estimator efficiency, the WSUR approach resulted in narrow confidence intervals and an efficiency gain of over 20%. The WSUR approach should be used in forest biomass modeling as it resulted in effective estimators while ensuring equation additivity, thus providing an easy and accurate alternative to estimate the initial biomass of eucalyptus stands in ecophysiological models.

Resumo em Inglês:

ABSTRACT. The search for alternative energy sources has fomented the study of several crops. The macauba palm crop, for instance, has been highlighted because of its particular relevance in Brazil due to its wide distribution across Brazilian territory and its potential for yielding high amounts of oil per cultivated hectare. However, the species is still most commonly harvested via extractivism, which results in low yields. Therefore, we aimed to analyze the dynamic behavior of the fruit-rachilla system when subjected to mechanical vibration to gather baseline information for the subsequent development of macauba harvesting machines. The fruit-rachilla system of the species was modeled for different fruit maturation stages and plant accessions. Natural frequencies and modes of vibration were determined by the stochastic finite element method (FEM), adopting the specific mass and the modulus of elasticity of the system as random variables, which enabled us to compile a dataset of natural frequencies based on the variability of the system properties. The mean values of the natural frequencies obtained in the vibration assays were 26.02 Hz at the green maturation stage and 21.22 Hz at the ripe maturation stage. The mean values of natural frequencies found in the simulation by stochastic FEM, referring to the third mode of vibration, were 26.05 Hz at the green maturation stage and 21.23 Hz at the ripe maturation stage. We concluded that the natural frequencies of the macauba fruit-rachilla system on the basis of different plant accessions showed a decreasing behavior during fruit maturation. The modes of vibration characterized by pendulum displacement did not differ among plant accessions or between fruit maturation stages.

Resumo em Inglês:

ABSTRACT. Grapevine trunk diseases are among the most important limiting factors of worldwide viticulture. In this context, we aimed to verify the effect of chemical fungicides, biological agents and plant extracts on the control of Lasiodiplodia theobromae in pruning wounds and their physiological effects in cv. Syrah grapevines. Plant extracts (clove, cinnamon, garlic, rosemary and lemongrass), commercial fungicides (difeconazole, tebuconazole, mancozeb, sulfur, pyraclostrobin, fosetyl-Al, and azoxystrobin), chitosan, Trichoderma harzianum and Bacillus subtilis were used for the in vitro trials. The protection of pruning wounds in the potted vines was studied using fosetyl-Al, tebuconazole, Trichoderma harzianum, Bacillus subtilis, garlic extract and clove extract. The experiments were carried out through two vegetative cycles: 2015/2016 and 2016/2017. The length of wood discoloration, pathogen re-isolation percentage, fresh mass of the pruning material, peroxidase activity, fluorescence, chlorophyll index, phenological stages, shoot length and leaf area were evaluated. The treatments with clove, garlic extract, tebuconazole, pyraclostrobin, mancozeb, fosetyl-Al and B. subtilis reduced mycelial growth by more than 90%. In the grapevines, the use of T. harzianum decreased the re-isolation of L. theobromae, but no differences were verified for the other plant evaluations. We concluded that the use of T. harzianum would be a potential option for wound protection without altering the physiological aspects of cv. Syrah grapevines.

Resumo em Inglês:

ABSTRACT. Melon bacterial fruit blotch (BFB) is the major bacterial melon disease in Northeastern Brazil. We evaluated the effects of applying a silicon (Si) slag on BFB suppressiveness in two melons cultivars as well as in soil chemical attributes and plant growth and nutrition. Slag was incorporated into the soil at concentrations equivalent to 0.00, 0.12, 0.24, 0.47, 0.71, and 1.41 g kg-1 of silicon. Plants were inoculated with Acidovorax citrulli 20 days after emergence. Results showed that amending the soil with Si slag improved the resistance of two melon cultivars against bacterial fruit blotch. Such an effect is probably related not only to the Si uptake by plants but also to changes in soil characteristics and improvement in plant nutrition. Both hybrid cultivars (AF4945 and Medellín) increased biomass, nutrient and Si accumulation as a function of Si doses applied to soil. According to Si concentration and Si to Ca ratio in plant tissue, both cultivars are regarded as intermediary Si-accumulators. We also observed that an intermediate dose of Si (0.71 g kg-1) posed better results on controlling melon bacterial fruit blotch than the highest dose tested. Long-term, field experiments testing Si slag rates and effects on melon yields are warranted.

Resumo em Inglês:

ABSTRACT. Asian soybean rust (Phakopsora pachyrhizi) is the main disease that affects soybean in Brazil. Fungicide applications are the main control method, but they can be influenced by the occurrence of rain. We aimed to study the control of Asian soybean rust in response to the occurrence of simulated rainfall at different times after fungicide application. The penetrant fungicides trifloxystrobin + prothioconazole (60 + 70 g a.i. ha-1) and azoxystrobin + benzovindiflupyr (60 + 30 g a.i. ha-1) and the nonpenetrant fungicides mancozeb (1,500 g a.i. ha-1), chlorothalonil (1,440 g a.i. ha-1), and copper oxychloride (672 g a.i. ha-1) were tested using two spray volumes: 70 and 150 L ha-1. Rain was simulated from 30 to 240 minutes after fungicide application. Soybean leaflets were collected and inoculated with a spore suspension of P. pachyrhizi (5.0 x 104 mL-1) and incubated in plastic boxes for 20 days. The trials were repeated twice. Nonpenetrant fungicides were more susceptible to rain washing, mainly when the 70 L ha-1 spray volume was used. For the penetrative fungicides, the best control percentages were obtained when the rainfall occurred between 120 and 180 minutes after application, while the protective fungicides had the best control percentages when the rainfall occurred approximately 240 minutes after application. The Asian rust control is affected by the characteristics of the fungicide applied, by the time interval between fungicide application and rain occurrence and by the spray volume.

Resumo em Inglês:

ABSTRACT. Tibraca limbativentris is considered one of the main species of insect pests in irrigated rice. This species can be found in plants in the vegetative and reproductive stages. This study aimed to select semivariogram models to estimate rice stem bug population densities by ordinary kriging. Two fields were used to survey the T. limbativentris population in Oryza sativa. A grid of 30 x 30 m was drawn, which generated 143 and 385 sample units for the first and second fields, respectively. Seven evaluations of two hundred plants per sampling unit were performed during cultivation. From the insect counts, the results were input into circular, spherical, pentaspherical, exponential, Gaussian, rational quadratic, cardinal sine, K-Bessel, J-Bessel, and stable semivariogram models via ordinary kriging interpolation and the best model was selected via cross-validation. Each assessment had a particular spatial structure and semivariogram model that best fit the experimental data.

Resumo em Inglês:

ABSTRACT. The objective was to study the habitat complexity of mite populations on Caryocar brasiliense trees under natural and cultivated field conditions. The study was performed in the municipality of Montes Claros, in the state of Minas Gerais, Brazil, over 3 years. Three types of areas were studied: 1) Cerrado, 2) pasture, and 3) a university Campus. Several chlorotic spots were detected on leaves with larger populations of Tetranychus sp. and Eutetranychus sp. (Tetranychidae). The greatest numbers of Agistemus sp. (Stigmaeidae) on leaves and Histiostoma sp. (Histiostomidae) and Proctolaelaps sp. (Ascidae) on fruits were observed in the pasture, and that of Histiostoma sp. on leaves in the pasture and on the university Campus. In general, the herbivorous mites (e.g., Tetranychus sp.) found on C. brasiliense plants were correlated with more clayey soils with a higher cationic exchange capacity; larger populations of mites (e.g., Agistemus sp. and Histiostoma sp.) were found on the C. brasiliense trees with the largest crown sizes; and associations between predator mites (e.g., Agistemus sp.) and phytophagous mites (e.g., Tetranychus sp.1) were observed. Greater habitat diversity and more complex plant architectures favored the mite populations. The positive effect of loamier soil on herbivorous mites indicates that these species are adapted to Cerrado conditions. Some recorded species of herbivorous mites can be pests in commercial plantations of C. brasiliense.

Resumo em Inglês:

ABSTRACT. Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), which is a gram-positive bacterium that causes wilting in several cultivated plants, is one of the main disease-causing bacteria in beans (Phaseolus vulgaris L.). Different techniques are employed to detect pathogens in bean plants; however, only a few slow and inefficient methodologies can be used to detect Cff. Hence, there is a need for rapid and efficient techniques to detect Cff for disease management. The objective of our study was to develop a technique to effectively detect Cff in the leaves of infected bean plants by optimizing a previously developed method. We modified the extraction method by reducing the amount of water used, replacing seeds with leaf tissues (obtained from the veins and petioles) and using CffFOR2 and CffREV4 primers specific for Cff. Our optimized method exploits a concentration gradient generated in the plant tissue through osmosis to disrupt the plant cell wall and efficiently isolate bacterial cells. DNA extracted from the isolated bacterial cells was amplified by polymerase chain reaction. This method allowed efficient detection of Cff in leaf tissues.

Resumo em Inglês:

ABSTRACT The objective of the present study was to isolate fungi from agricultural soils and evaluate fungal growth in culture medium contaminated with atrazine, glyphosate and pendimethalin. Filamentous fungi were isolated from agricultural soils and cultured in a modified culture medium containing 0, 10, 20, 50, and 100 μg mL-1 atrazine, glyphosate and pendimethalin for 14 days at 28°C. The fungi that presented optimal and satisfactory growth were plated in Sabouraud culture medium with 4% dextrose and containing the herbicides at concentrations of 0, 10, 20, 50, and 100 μg mL-1 for seven days at 28°C. The mean mycelial growth values were submitted to analysis of variance and the Tukey test (p < 0.05%) for comparison and relative growth determination, and maximum inhibition rates were calculated. The isolated fungi Aspergillus fumigatus, Fusarium verticillioides and Penicillium citrinum were shown to be resistant to atrazine, glyphosate and pendimethalin. F. verticillioides showed higher mean mycelial growth in the culture media contaminated with atrazine and glyphosate than the other two fungi. In the culture medium contaminated with pendimethalin, F. verticillioides, and A. fumigatus presented the highest mean mycelial growth values.

Resumo em Inglês:

ABSTRACT. The importance of rice (Oryza sativa) is indisputable this cereal is the staple food for half of the global population. Genetic progress estimation allows evaluation of the effectiveness of genetic improvement of crops and helps in the planning of breeding programs. This paper aims to estimate the genetic yield progress made by the program in the state of Minas Gerais, Brazil, which is run by the Epamig/UFV/Embrapa consortium. A total of 210 lines were evaluated by value for cultivation and use testing that was conducted in the municipalities of Janaúba, Leopoldina, and Lambari, from 1993 to 2016. Based on Vencovsky’s (1986) method, the genetic gains in Lambari, Janaúba, and Leopoldina were 1.46, 0.14, and 0.11%, respectively. The gain in Leopoldina was considered very low during the evaluated period. According to Breseghello’s (1998) method, the annual average genetic gain was 0.23 and 0.04% in Lambari and Janaúba, respectively. In Leopoldina, a yield gain of - 2.37% per year was observed for the evaluation period from 1994 to 1999, and a yield gain of 0.1% per year was observed from 2000 to 2016. These results can be explained by the focus on quality as a strategy for the breeding program in Minas Gerais State in the 1990s. Vencovsky’s (1986) and Breseghello’s (1998) methods were able to quantify yield gains and demonstrate the dynamics of the irrigated rice genetic improvement program in Minas Gerais State.

Resumo em Inglês:

ABSTRACT. This research aimed to explore the reproductive characteristics of three species of Psidium (P. guajava L., P. cattleyanum Sabine, and P. guineense Sw.) and estimate a probable reproduction strategy based on the pollen:ovule (P:O) methodology. The number of pollen grains per floral bud (NGPB), number of pollen grains per anther (NGPA), number of anthers per flower bud (NAB), number of ovules per flower bud (NOB), and the P:O ratio of each species were estimated. All species had a P:O ratio over 2,000 and were classified as xenogamous. P.guajava presented the highest values for all characteristics evaluated, with the NGPB at 3,777,519, the NOB at 584.50 and a P:O ratio of 6,462.82. Similarly, P. cattleyanum had a P:O ratio of 5,649.89 (NGPB 762,736 and NOB 135). However, P. guineense was considered facultative xenogamous, with P:O of 2,085.75, the NGPB at 741,484 and the NOB at 355.50. Thus, it was concluded that the studied species have a preference for allogamy and require many pollen grains to fertilize each ovule, demonstrating that the transfer of pollen to the stigma is not very specialized.

Resumo em Inglês:

ABSTRACT. The selection of superior genotypes of soybean entails a simultaneous evaluation of a number of favorable traits that provide a comparatively superior yield. Disregarding the population effect in the statistical model may compromise the estimate of variance components and the prediction of genetic values. The present study was undertaken to investigate the importance of including population effect in the statistical model and to determine the effectiveness of the index based on factor analysis and ideotype design via best linear unbiased prediction (FAI-BLUP) in the selection of erect, early, and high-yielding soybean progenies. To attain these objectives, 204 soybean progenies originating from three populations were examined for various traits of agronomic interest. The inclusion of the population effect in the statistical model was relevant in the genetic evaluation of soybean progenies. To quantify the effectiveness of the FAI-BLUP index, genetic gains were predicted and compared with those obtained by the Smith-Hazel and Additive Genetic indices. The FAI-BLUP index was effective in the selection of progenies with balanced, desirable genetic gains for all traits simultaneously. Therefore, the FAI-BLUP index is an adequate tool for the simultaneous selection of important traits in soybean breeding.

Resumo em Inglês:

ABSTRACT. The elucidation of the resistance mechanism of weeds to herbicides is important for management practices. The objective of this work was to investigate the resistance mechanism of glyphosate-resistant C. sumatrensis biotypes by determining the expression levels of the constitutive gene epsps and two ABC transport protein-coding genes designated m7 and m11 with RT-qPCR. Two biotypes of C. sumatrensis were evaluated: one resistant and one susceptible to glyphosate. The treatments consisted of the absence or application of two doses of glyphosate (1,080 and 8,640 g a.e. ha-1). Plant leaves were collected at 1 and 4 days after herbicide application. No difference was observed in epsps gene expression between the studied biotypes. The expression of the m7 and m11 genes revealed that both genes had higher relative expression in the resistant biotype with the application of glyphosate at both doses. The overexpression of the m7 and m11 genes in the resistant biotype treated with glyphosate reveals that these genes play a role in herbicide resistance. These genes may be involved in the sequestration of glyphosate into the vacuole lumen in the resistant C. sumatrensis biotype studied.

Resumo em Inglês:

ABSTRACT. Anthracnose, which is caused by the fungus Colletotrichum lindemuthianum, is one of the most widespread and important diseases of the common bean (Phaseolus vulgaris L.) in the world. The objective of the present study was to characterize the genetic resistance of the Beija Flor cultivar by inheritance and to conduct allelism tests. The inheritance test was conducted in the F2 population derived from the Beija Flor (resistant) x TU (susceptible) cross inoculated with race 2047 of C. lindemuthianum. Furthermore, allelism tests exhibited a fitted segregation ratio of 15R:1S, thereby indicating the independence of the Beija Flor gene from the following previously characterized genes: Co-1, Co-2, Co-4, Co-42, Co-6, Co-12, Co-14, Co-15, and Co-Pe. Based on the aforementioned results, we are proposing the symbol Co-Bf to designate the new anthracnose resistance gene in the Brazilian Andean common bean cultivar Beija Flor. This cultivar is an important source of resistance to C. lindemuthianum that should provide a valuable contribution to the common bean breeding program for anthracnose resistance.

Resumo em Inglês:

ABSTRACT. This paper aimed to evaluate the effectiveness of subset selection of markers for genome-enabled prediction of genetic values using radial basis function neural networks (RBFNN). To this end, an F1 population derived from the hybridization of divergent parents with 500 individuals genotyped with 1000 SNP-type markers was simulated. Phenotypic traits were determined by adopting three different gene action models - additive, additive-dominant, and epistatic, representing two dominance situations: partial and complete with quantitative traits having a heritability (h2) of 30 and 60%; traits were controlled by 50 loci, considering two alleles per locus. Twelve different scenarios were represented in the simulation. The stepwise regression was used before the prediction methods. The reliability and the root mean square error were used for estimation using a fivefold cross-validation scheme. Overall, dimensionality reduction improved the reliability values for all scenarios, specifically with h2 =30 the reliability value from 0.03 to 0.59 using RBFNN and from 0.10 to 0.57 with RR-BLUP in the scenario with additive effects. In the additive dominant scenario, the reliability values changed from 0.12 to 0.59 using RBFNN and from 0.12 to 0.58 with RR-BLUP, and in the epistasis scenarios, the reliability values changed from 0.07 to 0.50 using RBFNN and from 0.06 to 0.47 with RR-BLUP. The results showed that the use of stepwise regression before the use of these techniques led to an improvement in the accuracy of prediction of the genetic value and, mainly, to a large reduction of the root mean square error in addition to facilitating processing and analysis time due to a reduction in dimensionality.

Resumo em Inglês:

ABSTRACT. Heterosis has been one of the most studied phenomena since genetic studies were conceived. Knowledge of this phenomenon for the root distribution trait in beans (Phaseolus vulgaris L.) can favour the development of genotypes that are more tolerant to abiotic stresses. This study aimed to verify the occurrence of heterosis for the root distribution trait in hybrid F1 populations of common bean derived from crosses within and between gene groups. Thirty-six populations (six parents and 30 hybrids) were evaluated under field conditions in the agricultural years 2016/17 and 2017/18. The root distribution was assessed with the adapted Bohm method. The genotypes responded similarly to environmental changes (absence of an interaction). However, the root distribution differed significantly between the agricultural years. Comparisons between the mean of hybrids from crosses within each gene pool and the mean of parents did not reveal heterosis. The comparisons between gene groups showed significant differences only between BRS Embaixador x IPR Uirapuru, CBS 14 x IPR Uirapuru, and BAF 53 x IPR Uirapuru and the mean of parents. The absence of heterosis in the root trait can be explained by the degree of kinship between the gene groups, as well as some epistatic interactions.

Resumo em Inglês:

ABSTRACT. In addition to the agronomic traits of interest, soybean cultivars destined for human consumption must have specific attributes that meet the demands of the consumer market. To meet this demand, this study aimed to select progenies with agronomic and commercial traits of interest from soybean populations obtained from crosses between different food and grain genotypes and to estimate the genetic parameters of these populations. The F3:4 and F4:5 progenies that originated from the two crosses were evaluated in the 2015/16 and 2016/17 agricultural years, respectively, using the pedigree method. The experimental design utilized augmented blocks, while statistical analyses were performed by using the REML/BLUP methodology. The evaluated traits were plant height at maturity (APM), insertion height of first pod (AIV), lodging (AC), agronomic value (VA), number of pods per plant (NV), number of days to maturity (NDM), number of branches (NR), number of nodes (NN), 100-seed weight (PCS), and grain yield per plant (PG). The best progenies were selected, and the following genetic parameters were estimated: genetic variance, phenotypic variance, heritability, and selective accuracy. The estimates of the genetic parameters indicate the presence of high genetic variance in these populations. Heritability was high for most of the traits, indicating good potential for the selection of superior genotypes.

Resumo em Inglês:

ABSTRACT. In this study, we aimed to estimate general and specific combining abilities (GCA and SCA, respectively) and to verify genetic divergence (Rogers distance, Unweighted Pair-Group Method Using Arithmetic Average - UPGMA) using microsatellite markers in maize inbred lines. Using a partial diallel scheme, a total of 19 inbred lines were crossed as (9 x 10), which were derived from the single hybrids SG6015 and P30F53, respectively. The 90 hybrids were evaluated in an incomplete randomized block design with common checks and three replications during the 2017-2018 growing season. Flowering time, average plant height, ear height insertion, average ear diameter, ear length, number of lodged and broken plants, mass of 100 grains and grain yield were measured. According to the analysis of variance, GCA, and SCA were significant (p < 0.05) in all the measured traits; inbred line B as well as 1 and 8, derived from the single hybrids SG6015 and P30F53, respectively, were selected due to their higher GCA values in grain yield to be used in crosses as testers, while the single cross hybrid (B x 1) was selected due to their higher SCA value in grain yield to be used in future breeding programs. The molecular marker analysis divided the inbred lines into two groups, where the highest dissimilarity (0.74) was observed between lines A and 9; however, these did not result in a high SCA value, therefore the hybrids obtained by such crossings were not selected for grain yield.

Resumo em Inglês:

ABSTRACT. Cotton (Gossypium hirsutum L.) is the world’s leading natural textile fibre and is grown in over 60 countries, including Brazil, where it is an important agricultural commodity. The cultivation area currently covers approximately one million hectares in Brazil and has expanded into every region of the country, especially the Cerrado biome. Because of this expansion, it is necessary to analyse the influence of the environment on the genotype behaviour to optimize yields. Thus, the objective of this study was to compare fuzzy logic to traditional methods for selecting coloured-fibre cotton genotypes with high adaptability and yield stability. The experiment was conducted on the 2013/2014, 2014/2015, 2015/2016, and 2016/2017 crops of the Capim Branco farm at the Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil. The following methods were used to select genotypes for adaptability and stability: the Lin and Binns model, additive main effects and multiplicative interaction (AMMI) analysis and the Sugeno fuzzy logic controller. An interaction of the genotype with the environment that affected yield was detected. Environment 4 (the 2016/2017 crop) showed to the lowest genotype to environment interaction. The fuzzy logic approach showed agreement with AMMI and the nonparametric Lin and Binns method. The linguistic fuzzy logic used in the Sugeno fuzzy logic controller demonstrated the potential for selecting cotton genotypes in plant breeding programmes. The UFUJP-16 and UFUPJ-17 genotypes were adaptable, stable and showed promising yields within the tested environments. The fuzzy logic method was effective for estimating adaptability and stability.

Resumo em Inglês:

ABSTRACT. Maize forage is commonly used as silage in milk and beef cattle livestock production systems. Despite the wide variety of maize hybrids with high potential for grain production, few available hybrids have been developed exclusively for forage aptitude. The present study aimed to select S3 maize progenies derived from the single hybrid AS1572 based on the combining ability of forage traits in topcrosses with testers AG8025, 70.H26.1, and MLP102. The 135 resulting topcross hybrids were assessed in partial diallel in Guarapuava and Rio Bonito do Iguaçu, Paraná State, Brazil. Were evaluated the contents of neutral detergent fiber (NDF, %DM) and acid detergent fiber (ADF, %DM), forage dry matter yield (DMY, t ha-1), and in situ digestibility of forage dry matter (DIG, %DM). For all evaluated traits, the variability allowed us to select superior progenies. Progenies 3.1, 22.1, and 39.1stood out in terms of NDF, ADF, and DIG, whereas progenies 47.1, 73.1, 79.1, and 90.2 were efficient in increasing the forage dry matter yield. The testers AG8025 and 70.H26.1, of narrow genetic base, are the best to explore genetic variability among progenies.

Resumo em Inglês:

ABSTRACT. Our objectives were to evaluate general and specific combining ability (SCA) and genetic divergence among tropical maize inbred lines using single sequence repeat (SSR) markers. Thirteen inbred lines were crossed based on a complete diallel scheme. Hybrids and three checks were evaluated in a lattice experimental design. Silk and anthesis flowering, average plant height, average ear height, white spot (Pantoea ananatis) and gray leaf spot (Cercospora zeae-maydis) severity, and grain yield were evaluated. Significant differences (p < 0.05) for general and specific combining abilities were observed for all traits. Based on additive effects, inbred lines 1 (Flash) and 12 (SG 6015) were selected to reduce the flowering period and plant and ear height. Inbred lines 2 (CD 303) and 3 (AG 8080) were selected to reduce disease severity. For the simultaneous increase in grain yield and reduced severity of diseases, line 11 (AG 9090) as a parent or tester in topcross schemes is recommended. According to non-additive effects, crosses 2 (CD 303) × 13 (DKB 747) and 11 (AG 9090) × 12 (SG 6015) were selected for grain yield and future breeding programs. Six groups were identified using SSR markers; a major group contained six inbred lines. Because of the minor relationship between genetic divergence and SCA effects on grain yield limits, the use of the groups for future divergent crosses is recommended.

Resumo em Inglês:

ABSTRACT The objective of this study was to conduct a meta-analysis and test its efficiency in summarizing the heterogeneous data of heritability estimates for the traits of grain yield (GY) and popping expansion (PE), and to provide reliable estimates of selection gains in popcorn. Therefore, 97 heritability estimates (ĥ 2) for popcorn GY and PE in the broad and narrow sense were used. The main procedures underlying the estimation of the combined heritability (ĥ 2 + ) using the technique of meta-analysis consisted of i) an exploratory analysis of the set of heritability estimates to detect outliers using a box-plot chart, ii) the verification of the required statistical assumptions, iii) testing the involved heritability estimates for homogeneity, and iv) the calculation of the estimates of combined heritability. The meta-analysis facilitated the synthesis of the information pertaining to heritability in popcorn. The combined heritability estimates (ĥ 2 + ) in the broad sense for GY and PE were 0.5208 ± 0.0229 and 0.6356 ± 0.0209, respectively, and in the narrow sense were 0.3290 ± 0.0292 and 0.3083 ± 0.0298, respectively.

Resumo em Inglês:

ABSTRACT. The high price of rice hybrid seeds is one of the major limiting factors for increasing the use of this technology. An important step toward minimizing high rice hybrid seed cost is developing techniques that help improve hybrid seed yield. Our goal was to determine the proportion of seeds of line A (receptor) and line R (pollinator) that, under mixed sowing, would allow optimized rice hybrid seed production and grain quality. Trials were performed for two growing seasons in the southern region of Brazil. The cultivar INTA Puita was used as a pollinator and line 464 A as receptor. The experimental design was a randomized block with four replications. Treatments included six proportions of seeds of the INTA Puita (0.75, 1.5, 3.0, 6.0, 12.0, and 24.00%) mixture with seeds of line 464 A (99.25, 98.50, 97.00, 94.00, 88.00, and 76%, respectively). By increasing the percentage of the pollinator seeds (INTA Puita CL) from 0.75 to 24% in the mixture with the receptor (line 464 A), we increased yield of INTA Puita CL grains (7 to 2676 kg ha-1) and hybrid seeds (279 to 1493 kg ha-1). The mixture of different proportions of INTA Puita CL (pollinator) with the receptor (line 464 A) did not change the rice grain quality or the production cost. The cost of production per kg of hybrid seeds decreased quadratically with the increasing percentage of the pollinator (INTA Puita CL), from US$ 6.71 to US$ 1.23. Revenue achieved from the commercialization of the grains of INTA Puita CL with hybrid seeds 464 A showed quadratic increases with the increased percentage of INTA Puita cl in the mixture. Our results showed a potential technique that could be used to improve hybrid seed production, reduce cost per kg of hybrid seed and improve revenue from producing rice hybrid seeds.

Resumo em Inglês:

ABSTRACT Desiccation practiced during the preharvest period contributes to mechanized seed harvesting. This work aimed to verify whether wheat preharvest desiccation influences the morphological and physiological characteristics of the seedlings produced from the seeds of desiccated plants. The preharvest treatments included a combination of herbicides (glufosinate-ammonium, glyphosate, and paraquat) and phenological application stages (Zadoks: 83, 85, 87, and 92), as well as a control treatment (without application). Two wheat cultivars were used (BRS Parrudo and TBIO Sinuelo). Herbicide applications were observed to decrease the length and projected area of the shoots by 52 and 46%, respectively, as well as reduce the length, surface area and root volume when compared to the control treatment without application. The hydrogen peroxide concentration, as well as the enzymatic activity of guaiacol peroxidase, was observed to rise only in the treatments where the herbicides were applied. Physiologically, an increased hydrogen peroxide output was revealed, while the guaiacol peroxidase enzymatic activity increased in both cultivars, but with no effect noted in the superoxide dismutase enzymatic activity. The shoot and root morphology were negatively influenced, showing a rise in the enzymatic activity and hydrogen peroxide concentration in the seedlings from the desiccated plants.

Resumo em Inglês:

ABSTRACT. The adaptability of the strawberry is known; however, little is known about the morphological and agronomic performance of these runner plants when transplanted in the Southern Hemisphere. The objective of this study was to evaluate whether strawberry cultivars classified according to their flowering differ in morpho-phenology and agronomic performance. Six cultivars of strawberry were used, two of which were Short Day (SD), Camarosa and Camino Real, and four of which were Neutral Day (ND), Aromas, Albion, Monterey, and San Andreas. The cultivars were arranged in a randomized complete block design with four blocks. The research developed in two parts: one part as descriptive research (morphological performance and phenology) and the other part as explanatory research (morphology of the root system and the agronomic performance). In the descriptive research, the data about the strawberry cultivars were presented in a descriptive way. The data on morpho-agronomic performance (explanatory research) were submitted to analysis of variance and Tukey’s test at a 5% probability of error. It is inferred that there is variability among cultivars regardless of their classification in terms of flowering. In all cultivars, we observed a botanical structure called a hypsophyll that is not included in the morphological descriptors of the species.

Resumo em Inglês:

ABSTRACT. Grafting is an alternative method for the early production of Araucaria angustifolia seeds, and welding quality is essential for the success of the technique. The objective of this study was to create a classification of welding quality to estimate the percentage of scion survival. The patch and flute grafting techniques were used in a greenhouse and in the field. Survival was evaluated 270 days after grafting (DAG). At 60 DAG, observations of the graft connection region were made with the naked eye, classifying the connections into four welding classes. After 160 DAG, transverse cuts were performed on each class and visually and anatomically evaluated. Flute grafting presented higher initial survival (79%), but at 180 DAG, the survival rate of both techniques was similar (48% for flute and 41% for patch). There was greater scion survival for the class that had only two regions in contact with discontinuity in the bark. Stabilization of survival occurred after 180 DAG, regardless of the welding class. Visually, there were differences in welding quality; however, anatomically, all classes presented vascular connections. The visual welding quality assessment underestimated the percentage of scion survival. However, the vascular connection and development of parenchymatous tissue are promising for diagnosing grafting success.

Resumo em Inglês:

ABSTRACT. This study presents an evaluation of the viability of using protected urea under different irrigation depths to reduce nitrogen losses caused by the volatilization of ammonia (NH3) under the conditions of the Southwestern Amazon. The study was carried out at the Experimental Station of Embrapa Rondônia, in the municipality of Porto Velho, Rondônia State, Brazil. The experiment was conducted in a Red-Yellow Latosol and arranged in a 5 x 6 factorial design consisting of a combination of five treatments (N sources) with six irrigation depths. The sources of N were as follows: 1) urea (45.5% N); 2) urea (44.3% N) + 0.15% copper and 0.4% boron; 3) urea (45% N) + NBPT; 4) urea (43% N) + sulfur (1%); and 5) control (without N). The irrigation depths were 0, 5, 10, 15, 20, and 25 mm. The results showed that, regardless of the use of urease inhibitors, an irrigation depth of 10 mm is suitable for incorporating urea into the soil and stabilizing N losses from NH3 volatilization. NBPT is the most efficient inhibitor under nonirrigated conditions. All N sources promote increases in the concentrations of nitric and ammonia nitrogen in the soil. In the first 15 days after fertilizer application, the highest concentrations of ammonium were in the 0 - 10 cm and 10 - 20 cm soil layers, and NBPT showed the highest ammonium content compared to that of the other sources in the 0 - 10 cm layer. The nitric nitrogen content in the soil was slightly influenced by the irrigation depth in the first 15 days after fertilizer application. However, the ammonia nitrogen content decreased exponentially with the increase in irrigation depth due to the movement of ammonia in the soil.

Resumo em Inglês:

ABSTRACT. Strawberries are berry-type fruits that are very popular and widely consumed all over the world. The sensorial, physical-chemical and nutritional characteristics of strawberries are parameters of quality that influence the choices of consumers. However, these characteristics may be influenced by intrinsic and extrinsic factors that alter the fruit quality. The concentrations of nutrients and other chemical compounds in strawberries may increase and/or decrease according to the cropping system, maturation stage, climatic conditions, and preservation and storage methods. Factors characteristic of the cultivar, such as the genetic profile, may also influence the composition of strawberries. In this context, the objective of this research was to evaluate the sensorial, physical-chemical and nutritional characteristics of different strawberry cultivars to identify the genotype(s) with the best characteristics for commercialization and human consumption. The day-neutral strawberry cultivar "Aromas" and short-day strawberry cultivars "Camarosa, Camino Real, Dover, Sweet Charlie, and Tudla" were cultivated in the Olericultura Sector of the State University of the Midwest (UNICENTRO), Paraná State, Brazil. The fruits were characterized in relation to their physical-chemical, nutritional and sensorial aspects. According to the sensorial profiles, the Camarosa, Camino Real, Dover, and Tudla genotypes showed greater acceptability among consumers. Camarosa, Sweet Charlie, and Tudla presented better physical-chemical characteristics for human consumption, while the cultivars Camarosa, Dover, and Tudla had the best nutritional contents. In general, it is concluded that the genotypes Camarosa and Tudla are the most favourable for human consumption, according to their sensorial, physical-chemical and nutritional characteristics.

Resumo em Inglês:

ABSTRACT. In vitro culture systems based on liquid culture media are considered to be more effective than semisolid culture medium systems. Liquid culture media systems provide better nutrient availability for plant tissues, easier culture handling, and the potential for scaling up and automation. However, in vitro liquid culture requires more careful handling due to the potential for contamination and the possibility of negative effects, such as hyperhydricity or vitrification, that hinder the growth and development of the plant material. Temporary immersion bioreactors have emerged as a workable alternative for capturing the benefits of liquid media, though semisolid systems are still traditional. Many studies have shown that silicon (Si) is a beneficial plant nutrient. Silicon might have a positive effect in both semisolid and liquid in vitro systems. The objective of this study was to evaluate the effect of silicon on the micropropagation and acclimatization of banana plants cultivated in vitro by comparing liquid temporary immersion bioreactor technology and semisolid traditional culture systems. Different silicon concentrations (0 and 1 mL L-1) and culture systems (liquid temporary immersion bioreactor and semisolid traditional culture) were evaluated over a 36-day period. The growth characteristics plant size, fresh and dry weight, and number and length of leaves and roots were evaluated. After the 36-day in vitro growth period, plants were transferred to a greenhouse for acclimatization and were evaluated after 30 days for the same growth characteristics used in the in vitro studies. The temporary immersion bioreactor system resulted in greater growth of banana plants compared to the traditional semisolid system. Temporary immersion bioreactors also showed a positive interaction with Si and resulted in higher values for all growth characteristics in the acclimatization phase.

Resumo em Inglês:

ABSTRACT. Nitrogen management in crops is a key activity for agricultural production. Methods that can determine the levels of this element in plants in a quick and non-invasive way are extremely important for improving production systems. Within several fronts of study on this subject, proximal and remote sensing methods are promising techniques. In this regard, this research sought to demonstrate the relationships between variations in leaf nitrogen content (LNC) and sugarcane spectral behaviour. The work was carried out in three experimental areas in São Paulo State, Brazil, with different soils, varieties and nitrogen rates during the 2012/13 and 2013/14 seasons. A significant correlation was observed between the LNC and variations in the sugarcane spectra. The green and red-edge spectral bands were the most consistent and stable predictors of LNC among the evaluated harvests. Stepwise multiple linear regression analysis (MSLR) generated better models for LNC estimation when calibrated with experimental area, independent of the variety. The present research demonstrates that specific wavelengths are associated with the variation in LNC in sugarcane, and these are reported in the green region (near 550 nm) and in the red-edge wavelengths (680 to 720 nm). These results may help in future research on the direct in situ application of nitrogen fertilizers.

Resumo em Inglês:

ABSTRACT. Nitrogen is available in insufficient quantities in Brazilian soils, and is the nutrient that raises the most cost of production of maize. Nowadays there is a more interest in the use of alternative nitrogen sources, such as biological nitrogen fixation, to supply plant demand. Among the most used bacteria in association with grasses is Azospirillum brasilense. In this way this study aimed to establish a relationship between the genetic bases of corn and the forms of A. brasilense application and the effects on the plant morphological components, grain yield, and relative nitrogen contribution. Experiments were conducted during the 2013/14 and 2014/15 crop seasons. The experiments included two single hybrids, two double hybrids, and two triple hybrids inoculated with A. brasilense via seed treatment; foliar application during phenological stages V2, V2 + V4, and V4; and a control treatment without bacteria. The response varied with the hybrid and the year. In the 2013/14 crop, a significant difference was observed in the grain yield for the single hybrid AG9045 inoculated with A. brasilense via seed and foliar application in V2. In the 2014/15 crop, inoculation with A. brasilense via seed application resulted in significant increases in the grain yield for the triple hybrid BG7051. Foliar application of A. brasilense is an efficient alternative for the improvement of plant morphological traits, and inoculation via seed and with foliar application in V2 increases the relative contribution of N.

Resumo em Inglês:

ABSTRACT Arid and semiarid regions are vulnerable to water deficits and salinity. Citrus plants are sensitive to saline stress and require the use of tolerant scion-rootstock combinations. Thus, this study aimed to evaluate and classify citrus scion-rootstock combinations with respect to their tolerance to salinity during seedling formation in a protected environment. An experiment was conducted in a randomized block design with a 5 x 12 x 2 factorial scheme corresponding to five levels of water salinity (0.8, 1.6, 2.4, 3.2, and 4.0 dS m-1) applied in 12 citrus rootstocks grafted with two scion varieties: ‘Tahiti’ acid lime and ‘Star Ruby’ grapefruit. The scion-rootstock combinations were evaluated for accumulated dry matter and survival index at 330 days after sowing the rootstocks. Salinity exerted different effects on the dry matter formation of scion-rootstock combinations. ‘Star Ruby’ was less sensitive to salinity, particularly when the rootstocks were the hybrids from ‘Sunki of Florida’ mandarin (TSKFL) with ‘Troyer’ citrange (CTTR) - 013 (TSKFL x CTTR - 013), common ‘Sunki’ mandarin (TSKC) with ‘Argentina’ citrange (CTARG) - 019 (TSKC x CTARG - 019), TSKC with ‘Swingle’ citrumelo (CTSW) - 031 (TSKC x CTSW - 031), and the trifoliate hybrid (HTR) - 069, as well as the varieties Volkamer lemon and Santa Cruz Rangpur lime. When grafted with ‘Tahiti’ acid lime, the rootstocks displaying the less sensitive to salinity were TSKFL x CTTR - 013 and TSKC x CTARG - 019.

Resumo em Inglês:

ABSTRACT. An increase in atmospheric CO2 levels and global climate changes have led to an increased focus on CO2 capture mechanisms. The in situ quantification and spatial patterns of forest carbon stocks can provide a better picture of the carbon cycle and a deeper understanding of the functions and services of forest ecosystems. This study aimed to determine the aboveground (tree trunks) and belowground (soil and fine roots, at four depths) carbon stocks in a tropical forest in Brazil and to evaluate the spatial patterns of carbon in the three different compartments and in the total stock. Census data from a semideciduous seasonal forest were used to estimate the aboveground carbon stock. The carbon stocks of soil and fine roots were sampled in 52 plots at depths of 0-20, 20-40, 40-60, and 60-80 cm, combined with the measured bulk density. The total estimated carbon stock was 267.52 Mg ha-1, of which 35.23% was in aboveground biomass, 63.22% in soil, and 1.54% in roots. In the soil, a spatial pattern of the carbon stock was repeated at all depths analyzed, with a reduction in the amount of carbon as the depth increased. The carbon stock of the trees followed the same spatial pattern as the soil, indicating a relationship between these variables. In the fine roots, the carbon stock decreased with increasing depth, but the spatial gradient did not follow the same pattern as the soil and trees, which indicated that the root carbon stock was most likely influenced by other factors.

Resumo em Inglês:

ABSTRACT. The aim of this work was to verify the potential of chelate-based products containing calcium, copper, manganese, and zinc for the management of Pantoea ananatis, Puccinia polysora, Cercospora zeae-maydis, Exserohilum turcicum, Diplodia macrospora, and Pseudomonas avenae in crop maize growth in the summer season, as well as their influence on agronomic characteristics. The treatments included commercial chelate-based products of amino acids with the elements calcium (15%), copper (5%), manganese (15%), and zinc (10%) at doses of 0.5 kg ha-1, 0.3 L ha-1, 0.4 kg ha-1, and 1 L ha-1, respectively; fungicides (20% azoxystrobin and 8% cyproconazole at a dose of 0.3 L ha-1 + 25% propiconazole at a dose of 0.4 L ha-1); and water. The tests were carried out under field conditions for two consecutive years with two simple hybrids. The plant height, stem diameter, number of rows per ear, number of grains per ear row, productivity and mass of one thousand grains, as well as the severity of leaf diseases, were all evaluated, and chemical analysis of the leaves was performed. In the 2016/2017 growth season, for the number of rows per ear and number of grains per row, the fungicide treatment showed the highest values, whereas for the mass of one thousand grains and productivity, the chelate treatments did not differ from the fungicide treatment and were different from the water treatment. In the 2017/2018 growth season, for the mass of one thousand grains and yield, only the fungicide treatment was different from the water treatment. For all the chelates studied for both hybrids, there was no difference in nutrient content before and after foliar application. It can be concluded that calcium, copper, manganese, and zinc products may influence agronomic traits but not the severity of the diseases evaluated in these two hybrids of maize under the edaphoclimatic conditions in which the study was carried out.

Resumo em Inglês:

ABSTRACT. Sugar apples have attracted attention in recent years due to their medicinal and nutritional properties. However, the shelf life of sugar apples is one of the most concerning problems owing to their perishability. This work aimed to determine the ideal harvest time for sugar apple fruits in relation to different classes of carpel interspaces. Therefore, fruits were classified into three stages according to the carpel interspace: stage 1 (0.0 - 2.0 mm); stage 2 (2.1 - 3.0 mm); and stage 3 (3.0 - 4.0 mm). After harvesting, the fruits were evaluated daily in the laboratory regarding their physical and physicochemical aspects until they reached the point of consumption (horticultural maturation). The following variables were evaluated: fruit diameter and length (mm); fruit, peel, pulp, and seed masses (g); color index, including the chromatic attributes L* (luminosity), C* (chroma), and h* (hue angle); bark firmness (N); soluble solids (°Brix); titratable acidity (g citric acid 100 g-1 of pulp-1); pulp yield; and ratio SS/TA. Fruits at stage 3 showed larger diameters, less firmness, and better chromaticity means. Fruits at stages 2 and 3 had eight days of postharvest life. However, fruits at stage 2 took longer for 50% of the fruits to be ready for consumption. The results demonstrate that stages 2 and 3 can be determinants for the harvest time of sugar apples.

Resumo em Inglês:

ABSTRACT. Environmental and production factors might affect grapevine physiology. Estimating these effects is essential for planning the harvest and predicting the quality of grapes. The aim of this study was to characterize the quality and antioxidant potential of ‘BRS Cora’ grapes with different training systems and rootstocks in production cycles of the second half of the year under tropical conditions. The experimental design was randomized blocks with sub-subdivided plots over time. Three training systems and two rootstocks were studied in production cycles referring to the second halves of 2017 and 2018. In 2017, the grapes of plants trained with lyre and vertical shoot positioning (VSP) had the highest soluble solids and sugars contents, and in 2018, this response occurred with the overhead trellis system. There was lower variation in titratable acidity between cycles of grapevines trained with VSP and lyre, as well as in those grafted onto ‘IAC 572’. In 2018, lyre with ‘IAC 572’ promoted higher pigment accumulation. Climatic conditions in 2017 provided a higher accumulation of polyphenols and antioxidant activity in grapes of plants trained with lyre with ‘IAC 766’. The efficiency of the training system within each cycle, associated with the effect of the rootstock, resulted in differentiated responses according to climatic conditions.

Resumo em Inglês:

ABSTRACT. A study was conducted during four growing seasons to investigate the rooting capacity and survival percentage of cassava seedlings from stem cuttings selected based on their number of leaves. The experimental design was a randomized block design with five replications in a factorial scheme (4 × 2 × 2), totalling 16 treatments. Treatments consisted of combinations of growing season (September 22, October 7 and 19, and November 25), stem cuttings smaller (15 to 19.99 mm) and larger (20 to 25 mm) than 20 mm in diameter, and number of leaves on the stem cuttings (3 to 5 and 6 to 8 leaves). The experiment was carried out during the four growing seasons in a Van der Hoeven greenhouse. The greenhouse, as well as the benches on which the treatments were placed, had a north-south orientation. The greenhouse has an automatic mist irrigation system, and the mean temperature was 25 °C. The plant height at planting, number of leaves at planting, and number of leaves at 7 days after planting were measured. The final number of leaves, final plant height, shoot dry matter, root dry matter, and total dry matter were measured after acclimatization. Stem cuttings between 20 and 25 mm in diameter should be used to produce cassava seedlings with the rapid multiplication method. Cuttings with 6 to 8 visible leaves should be collected, and the cuttings should be planted at the end of September.

Resumo em Inglês:

ABSTRACT. Muntingia calabura fruits are rich in bioactive compounds such as antioxidants, and the consumption of these compounds is associated with cancer prevention and aging. In this study, mathematical models were used to fit the experimental data of the Muntingia calabura peel drying kinetics, and the effective diffusion coefficient, activation energy and thermodynamic properties of the process were determined. Then, the effect of the drying temperature on the antioxidant activity and phenolic compounds of fruit peels was examined using conventional extraction and ultrasonication. Among the analyzed models, the logarithmic model was selected to represent the drying phenomenon of the calabura peel kinetics. The effective diffusion coefficient decreased by 74% as the temperature increased from 40 to 60°C, and the activation energy for liquid diffusion during drying was 23.96 kJ mol-1. The enthalpy and entropy decreased with increasing temperature, while the Gibbs free energy increased by 5% for each 10°C increase in temperature. Regarding the content of phenolic compounds and the antioxidant activity of the calabura peel, it was observed that an increase in the drying temperature had a positive effect on the conservation of the bioactive compounds, making it possible to conclude that drying at 60°C and ultrasound extraction are the most suitable approach to conduct the process.

Resumo em Inglês:

ABSTRACT. To diagnose and monitor the nutritional status of commercial crops, reference standards must be established based on chemical analyses of soils and leaf tissues. Therefore, the objective of this study was to establish sufficiency ranges, DRIS standards and leaf nutritional diagnoses for palisade grass pastures in the rainy and dry seasons. Of a total of 105 sampled pastures, the 20 highest-yielding areas were used to establish reference standards. In the other, low-productivity pastures, the nutritional status was diagnosed in both the rainy and dry seasons for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), nickel (Ni), molybdenum (Mo), and zinc (Zn). A productivity of 15 tons ha-1 year-1 was determined as the threshold to separate high-yielding (> 15 tons ha-1 year-1) pastures from low-productivity pastures (< 15 tons ha-1 year-1). Sufficiency ranges and foliar DRIS standards were established for palisade grass pastures in the rainy and dry seasons, which resulted in the recommendation of region- and season-specific sufficiency ranges and DRIS leaf standards. In the rainy season, in more than 50% of the evaluated pastures, nutritional deficiencies in all nutrients except K, B and Zn were observed, while in the dry season, only N, P, Cu, and Mn were deficient.

Resumo em Inglês:

ABSTRACT. Some plants do not demand a lot of chilling hours, but methods to overcome dormancy promote more vigorous and productive plant. This study aimed to assess hydrogen cyanamide and nitrogen fertilizer with different concentration to growth and production in ‘Roxo de Valinhos’ fig tree. Two crop cycles (2015/2016 and 2016/2017) was performed in São Manuel city, São Paulo State, Brazil. Phenological and productive data was evaluated in a 2 x 5 factorial (Product x Concentration), organized in randomized complete block design, with three trees by plot. The factor products had as level hydrogen cyanamide and nitrogen fertilizer and the factor concentrations was constituted by 0, 1, 2, 3, and 4%. Furthermore, the following data was evaluated: number of days for budbreak, number of buds per plant, harvest period, branch length and diameter, leaf number, leaf area, number of fruits per plant, fruit mass, production and yield. Results indicated that both products anticipated the sprouting and promoted a higher number of buds overcome the dormancy. Plant production was higher in both cycles when the products were used (2.1 and 2.7, respectively). At last, hydrogen cyanamide showed better outcomes due to the higher number of fruits and production.

Resumo em Inglês:

ABSTRACT. The objective of this work was to test long-term trends in the planting date of gladiolus to ensure marketing of these flowers on Mother’s Day and All Souls’ Day in Santa Maria (latitude: 29° 43’ S, longitude: 53° 43’ W, and altitude: 95 m), Rio Grande do Sul State, Brazil. Minimum and maximum air temperature data from 106 years were used (1912-2017) to simulate the optimum planting date indicated through the PhenoGlad model, aiming to harvest floral stems for both market dates for early, intermediate I, intermediate II and late cultivars. The homogeneity of the historical series was tested using the run test, and the historical trend was tested by the Mann-Kendal test. The magnitude of the trend was estimated with simple linear regression, and the descriptive statistics were calculated. For marketing on Mother’s Day, there was no historical trend that implied a change in the planting date of gladiolus for any of the development cycles. For marketing on All Souls’ Day, there was a positive historical trend only for the early and intermediate cycles I and II; thus, the increase in air temperature implied a delay of 9.2 days, 9.5 days and 6.9 days for the planting date, respectively, indicating that a shortening of the gladiolus development cycle occurred, mainly in late winter/early spring.

Resumo em Inglês:

ABSTRACT. The present study was carried out to evaluate the antioxidant activity of and the content of bioactive compounds in camu-camu fruits harvested at different maturation stages and stored. The fruits were harvested in the municipality of Cantá, Roraima State, Brazil. The experimental design was completely randomized, with three replications, in a factorial arrangement consisting of three different maturation stages (immature, semi-mature and mature) and eight days of storage (3 x 8). The fruits were analysed every day regarding total vitamin C, carotenoids, anthocyanins, flavonoids, total phenolic compounds, and antioxidant activity (FRAP and DPPH). According to the results obtained, the interaction of maturation stages x eight days of storage had a significant effect according to the F test at 5% probability. The highest antioxidant activity (FRAP) was observed in the fruits harvested in the semi-mature stage, providing a longer shelf life. The carotenoid pigment, flavonoid, anthocyanin, and vitamin C contents were higher in the fruits harvested in the mature stage, and this stage was the most suitable for obtaining these functional biocompounds. Additionally, in mature fruits, the highest mean content of total phenolics and antioxidant activity (DPPH) were observed during storage. It was concluded that the mature stage is the most recommended for the extraction of pigments and antioxidant biocompounds from camu-camu fruits.

Resumo em Inglês:

ABSTRACT. The objective of this study was to evaluate the forage yield and morphological responses of 34 cactus pear (Nopalea cochenillifera and Opuntia ficus indica) genotypes. The genotypes were planted in a randomized complete block design, with 34 treatments and three replicates. After 330 days of cultivation, morphological characteristics, plant mortality and pest and disease occurrence on the plants were assessed, and plant cutting was performed. Multivariate analyses were performed to assign the 34 cactus genotypes to homogenous groups. The average Euclidian distance was adopted as a dissimilarity measurement for use with the standardized data Variables with relatively high levels of independence among the agronomic categories and with biological importance to animal nutrition and forage yield were assessed. To identify associative effects, Pearson’s correlation analysis was performed among all the studied variables. The formation of five distinct groups was observed, and some morphological responses correlated with the productivity characteristics. Green mass production was positively correlated with dry mass production, water accumulation, water-use efficiency, water accumulation and cladode number per plant. The following genotypes had remarkably high yields of dry and green mass, a greater ability to accumulate water and relatively high water-use efficiency and support capacity: Negro Michoacan (V07), Tamazunchale (V12), California (V14), Orelha de Elefante Mexicana (V17), and Amarillo 2289 (T32).

Resumo em Inglês:

ABSTRACT. In agriculture with 4.0 technologies, developing a decision model with a 0.0 cost is attractive to small farmers. In water management, if this approach could be used to promote sustainability and optimization, it could become a pathway to reach the sustainable development goal in 2030. The core of this work is the development of a 4.0 mathematical model (based on fuzzy concepts) to verify the benefits of the production of lettuce irrigated with magnetically treated water at different replacement rates. This approach is achieved using computational 4.0 software and manual methods. The aim of mathematical modeling is to understand or explain a natural phenomenon associated with a given area of knowledge, and fuzzy-rule-based systems have been widely used in different types of in-depth research.

Resumo em Inglês:

ABSTRACT. High CO2 atmospheres have been reported to be accountable for slower ripening processes of many fruit species. In modified or controlled atmosphere storage of mangoes (Mangifera indica L.) delayed ripening is attributed to the effects of CO2 on ethylene biosynthesis, which is reduced under CO2 concentrations beyond 10%. In the present work the objective was to determine if those elevated CO2 atmospheres on ethylene synthesis could be attributed to the action of CO2 upon ACC oxidase. Mature green or tree ripe `Tommy Atkins` mangoes were, in four experiments, held in a flow through system of either 10 or 25% CO2 mixed to 5% O2 or only air for 14 or 21 days at 5, 8 or 12°C. Mangoes in the 25% CO2 atmosphere did not produce detectable levels of ethylene, whereas under 10% CO2 the production rates were significantly suppressed at 5 or 8°C. However, 1-aminocyclopropane-1-carboxylic acid (ACC) concentrations in mango mesocarp tissue at retrieval from storage were similar to the air controls and ACC synthase activity was not completely inhibited. The direct effects of CO2 concentrations on ACC oxidase activity is to be considered the most important factor in inhibiting ethylene biosynthesis of mangoes under 25% CO2 atmospheres.

Resumo em Inglês:

ABSTRACT The aim of this study was to verify if a growth reduction of yellow passion fruit seedlings’ growth morphophysiology and quality could be changed by paclobutrazol applied through seedling immersion. The experiment was conducted in a greenhouse, with seedlings grown in polyethylene tubes (290 cm3), with substrate. At 40 days after sowing, the seedlings were immersed in an aqueous solution of paclobutrazol at concentrations of 0, 50, 100, 150, and 200 mg L-1. The experiment was conducted in a randomized block design, with five treatments (paclobutrazol concentrations) and four replicates. At 15 and 30 days after treatment, growth characteristics were evaluated. At the end of the assay, destructive evaluations related to mass determination, total leaf area, and seedling quality index were performed. Paclobutrazol treatment induced restrictions in seedling growth, except for fresh and dry mass of root and total fresh mass. Based on these characteristics, the increase in values induced by paclobutrazol was verified. The seedling quality, defined by the major value of the Dickson quality index and a smaller robustness index, was higher when submitted to paclobutrazol treatment.

Resumo em Inglês:

ABSTRACT This work aimed to characterize the biochar produced from residues of coconut fruit and to evaluate how it might beneficially alter the retention capacity of water and nutrients in soils with a sandy texture. The biochar was produced in a retort furnace and later analyzed to determine its chemical and physical characteristics. Experiments to analyze the retention potential of the biochar for water and nutrients were performed in PVC columns filled to a 400 mm depth, with the upper 300 mm receiving treatments that consisted of 0, 1, 2, 3, 4, and 5% (p p-1) biochar mixed with soil. For the nutrient retention experiment, in addition to the biochar concentrations, the treatments received the same NPK fertilization. The experiments were performed in a completely randomized design with four replications. The water retention in the upper 300 mm, as well as the pH, effective cation exchange capacity (ECEC) of the substrate, base saturation, and concentrations of P and K, increased with increasing biochar concentration. Coconut biochar demonstrated potential for increasing water retention and improving nutrient retention in sandy soils.

Resumo em Inglês:

ABSTRACT In regions with high temperatures, carrot cultivation is impracticable, as high temperatures tend to reduce yield and quality of the product. However, with the advent of summer cultivars, carrot cultivation in these regions has become viable. The aim of this work was to evaluate the performance of ten carrot cultivars in different planting seasons. The experiments were carried out at the Rafael Fernandes Experimental Farm of the Federal Rural Semiarid University (UFERSA). The experiments were carried out in May, June, July and August of 2017. The experimental design was a randomized block with ten treatments and four repetitions. The characteristics that were evaluated were the root classification (long, average and short roots); commercial, non-commercial and total yield; dry plant weight and root fresh weight. Both the planting season and the cultivar played important roles in agronomic performance throughout the experimental period. In May and June, the highest average yields and plant growth were obtained (43 and 45 t ha-1 yield, respectively). Hybrid cultivars showed better performance than open-pollinated cultivars in terms of yield. The Brasília, BRS Planalto, and Kuronan varieties showed poor performance in all the evaluated characteristics.

Resumo em Inglês:

ABSTRACT Salvia hispanica L. is an alternative crop cultivated by farmers who want to diversify their production. However, this species is sensitive to salinity, which affects its germination negatively. Seed priming with different attenuators is a technique with potential to mitigate the effects of salt stress. Thus, the objective of this study was to evaluate the effect of seed priming with the use of different attenuators on the germination, growth, and organic solute accumulation of S. hispanica seedlings under salt stress. The experimental design was completely randomized, with treatments distributed in a 4 × 5 factorial scheme, corresponding to four seed priming treatments and five osmotic potentials, with four replicates of 50 seeds in each treatment. The seed treatments consisted of presoaking seeds for 4h in salicylic acid, gibberellic acid, and distilled water and the control treatment, which did not involve soaking. These seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3, and -0.4 MPa, using NaCl as an osmotic agent to simulate the different salinity levels. Among all the treatments implemented, S. hispanica seed priming with salicylic acid was the most efficient in mitigating the salt stress effects.

Resumo em Inglês:

ABSTRACT Producers in the northeastern semiarid region of Brazil have been cultivating irrigated corn. The commercialized product comprises mainly green ears and silage. However, the irrigation of crops for dry grain has been questioned regarding costs and price competitiveness in relation to the same non-irrigated product cultivated in other regions. In recent years, the use of drip tapes and fertigation has spread among corn producers in the region. The aim of this study was to determine the N dose, via fertigation, which provides the maximum economic production of corn for dry grain, in two crop seasons (summer and winter), in the semiarid region of Brazil. The experimental design was performed in randomized blocks, with four replications. In both crops, the treatments consisted of four doses of N (0, 80, 160, and 240 kg ha-1) applied in the form of urea. In the hybrid corn (Bt Feroz), the N content was evaluated in terms of leaves, grain yield, gross and net incomes, the rate of return, and the profitability index. Independent of the crop season, the yield of dry grain (5,441.03 kg ha-1) was highest when the corn was fertigated with a dose of 104.05 kg ha-1 N. The highest net incomes of the dry grain were obtained with 80 kg ha-1 N in summer (R$ 1,190.78 ha-1) and 160 kg ha-1 N in winter (R$ 2,757.54 ha-1). The winter crop was more favorable to the economic production of dry grain.

Resumo em Inglês:

ABSTRACT This study aimed to evaluate the beverage quality of Coffea canephora genotypes in different environments of the western Amazon to assist plant selection and new cultivar development. To analyze beverage quality, samples of cherry coffee beans were collected separately for each genotype from clonal competition trials installed in the municipalities of Ouro Preto do Oeste, Alta Floresta do Oeste, Porto Velho, and Ariquemes in Rondônia State and Rio Branco in Acre State (Brazil). The beverage quality was assessed using the Robusta Cupping Protocol, which attribute to each genotype a score in a range from 0 to 100, highlighting nuances. Analysis of variance and principal components using reference points were used to quantify genotype x environment interaction (G x E). The analysis of variance indicated that genotypic and G x E interaction effects were significant (p < 0.01). By using a centroid dispersion method, we could identify four clones of low, eight of specific (to favorable or unfavorable environments), and seven of broad adaptability to the environments. The clones BRS 2314, 11, and 17 had average quality scores above 80 in all environments, with potential for specialty coffee production. The clones BRS 1216, BRS 3220, and BRS 3193 presented unstable behavior, with beans of higher quality in some of the evaluated environments. Such inconsistency in clone behavior is caused by unpredictable changes in plant performance in different environments. Our results indicate that both genotypic (clones) and G x E interaction effects are important for the expression of coffee beverage quality. However, the clones BRS 3213, BRS 3210, and BRS 2299 had less prominent nuances, with lower potential for specialty coffee production.

Resumo em Inglês:

ABSTRACT Italian ryegrass (Lolium multiflorum L.) is a highly competitive weed widely disseminated worldwide that affects both summer and winter crops. The development of predictive emergence models can contribute to optimizing weed management. The aim of this study was to develop and validate an empirical emergence model of Italian ryegrass based on soil thermal time. For model development, cumulative emergence in two locations was obtained, and the model was validated with data collected in an experiment conducted independently. Three commonly used emergence models were compared (Gompertz, Logistic, and Weibull). The relationship between emergence and soil thermal time was described best by the Gompertz model. The Gompertz model predicted Italian ryegrass emergence start at 300 thermal time (TT), reaching 50% emergence at 444 TT, and 90% at 590 TT. Model validation performed well in predicting Italian ryegrass emergence and proved to be efficient at describing its emergence. This is a potential predictive tool for assisting farmers with Italian ryegrass management.

Resumo em Inglês:

ABSTRACT The initial development of the common bean plants (Phaseolus vulgaris L.) that rely on symbiotic nitrogen (N) can be limited when active N2 fixation is delayed. Thus, adequate plant growth with rhizobium inoculation could require supplemental mineral N, which in turn may inhibit the symbiosis. Five experiments were performed using hydroponics to identify the initiation of nodulation and nitrogenase activity in common bean cultivars, and effects of mineral N addition on plant nodulation and growth. Three experiments evaluated the initial growth of five inoculated bean cultivars in the absence or presence of mineral N, while two experiments evaluated the effect of mineral N addition until the beginning of the reproductive stage. The first root nodules appeared 10 days after transplanting (DAT), while nitrogenase activity was initiated at 11 DAT. Large seed cultivars had lower levels of initial nodulation and nitrogenase activity than those of small seeds. Inoculated plants showed limited shoot growth that lasted until 21-25 DAT relative to the inoculated plants that received mineral N. Moreover, adding mineral N greatly reduced the nodule mass more than the nodule number, and caused an even greater reduction in nitrogenase activity. Mineral N that was applied until 15 DAT enhanced nodulation and nitrogenase activity without limiting shoot growth relative to the plants that received N throughout their growth. In contrast, plants that received N after 15 DAT had lower levels of nodule mass and nitrogenase activity than those of the plants that were only inoculated. Hence, these results indicate that symbiotic N was not sufficient for an adequate initial growth of the common beans. Therefore, some supplemental N is necessary, which should be added at sowing to stimulate plant growth without inhibiting further nodulation and N fixation.

Resumo em Inglês:

ABSTRACT. The intensification of anthropogenic activities on soils contributes to soil loss through erosion. Moreover, the pattern of soil loss in the Cobra River watershed, located in the semiarid region of Rio Grande do Norte, is related to the history of land use and occupation, mainly from agriculture and the red ceramic industry, as well as the climatic seasonality of the region. Thus, the objective of this work was to identify the pattern of soil loss from the Cobra River microbasin in the state of Rio Grande do Norte. For this, the following analyses were performed: a survey of land use class areas for the years 1987, 1997, 2007 and 2017 as part of the Mapbiomas project; estimation of basin soil loss for these years; and quantification of areas of erosion vulnerability classes for this period. QGIS software was used to treat georeferenced data. According to the results, the land cover classes in the rich Cobra River microbasin fluctuated over time. Potential soil loss from the watershed increased from 1987 to 2017, with an increase of approximately 20 million megagrams of potentially erodible soil. The study of soil loss in a microbasin located in the Brazilian semiarid region should consider the variation in land cover over time, climatic seasonality and anthropic activity. To this end, it is important to use geotechnology and geoprocessing techniques to conduct a more robust spatiotemporal analysis.

Resumo em Inglês:

ABSTRACT The implementation of integrated agricultural production systems is considered a promising strategy for sustainable agricultural intensification in Brazil. This study aimed to evaluate the effects of different monoculture and integrated production systems on the microbiological attributes and organic carbon of soil from the Cerrado region in Piauí, Brazil. Soil samples were collected from the 0.0-0.10-m layer in the following systems: no-tillage (PD), pasture (PAS), exclusive eucalyptus cultivation (CEE), integrated livestock-forest system (IPF) and a native Cerrado (CN) area, which was used as reference. Total organic carbon (TOC) and nitrogen (NT) contents, microbial biomass carbon (CMIC), microbial respiration (MR), microbial quotient (qMIC), metabolic quotient (qCO2), as well as the activities of the hydrolysis of fluorescein diacetate (FDA), acid phosphatase, β-glucosidase and urease enzymes were evaluated. High TOC contents were found in the CEE, IPF and PAS systems, and high CMIC and qMIC values were found in the CN and CEE systems. The variables MR, qCO2 and enzymatic activity varied as a function of the management systems. The IPF and CEE systems caused improvements in the soil attributes, with increases in organic carbon and microbial biomass. The IPF integrated production system promoted improvements in the microbiological indicators of soil quality and was considered an environmentally sustainable agricultural production system. The transition from CN to agricultural areas caused changes in the soil microbiological indicators, which were perceived several years after anthropogenic intervention, indicating that even with the adoption of conservation systems, it was not possible to reestablish the soil microbial biomass.

Resumo em Inglês:

ABSTRACT Soil contamination by metals threatens both the environment and human health and hence requires remedial actions. The conventional approach of removing polluted soils and replacing them with clean soils (excavation) is very costly for low-value sites and not feasible on a large scale. In this scenario, phytoremediation emerged as a promising cost-effective and environmentally-friendly technology to render metals less bioavailable (phytostabilization) or clean up metal-polluted soils (phytoextraction). Phytostabilization has demonstrable successes in mining sites and brownfields. On the other hand, phytoextraction still has few examples of successful applications. Either by using hyperaccumulating plants or high biomass plants induced to accumulate metals through chelator addition to the soil, major phytoextraction bottlenecks remain, mainly the extended time frame to remediation and lack of revenue from the land during the process. Due to these drawbacks, phytomanagement has been proposed to provide economic, environmental, and social benefits until the contaminated site returns to productive usage. Here, we review the evolution, promises, and limitations of these phytotechnologies. Despite the lack of commercial phytoextraction operations, there have been significant advances in understanding phytotechnologies' main constraints. Further investigation on new plant species, especially in the tropics, and soil amendments can potentially provide the basis to transform phytoextraction into an operational metal clean-up technology in the future. However, at the current state of the art, phytotechnology is moving the focus from remediation technologies to pollution attenuation and palliative cares.