ABSTRACT Black pepper is widely produced in Brazil, though there are few studies related to its water requirements and the effects of water deficit (WD) applied under tropical conditions. The growth, sensitivity to WD, and first-year productivity of irrigated plants from the Bragantina cultivar were evaluated, employing an irrigation system with automatic management. The plants were cultivated in plastic pots installed in the field for 391 days using emitters with different flow rates (2.2 [T1], 3.3 [T2], 4.3 [T3], and 5.3 L h–1 [T4 – control]). Fresh weight of the leaves, stems, and shoots, and dry weight of the leaves, stem, roots, and shoots as well as the total dry weight of the plant, were evaluated. Productivity was determined by evaluating the grains and spikes from a single harvest. Yield results and the actual versus maximum evapotranspiration rate for the entire growing season was used for calculating the Ky coefficient. Despite 1,346 mm of rainfall, the irrigation system was activated 165 times, distributing a mean volume of 19.0 (T1), 28.5 (T2), 37.1 (T3), and 45.8 L per plant (control). All traits were negatively affected by the WD, and the Ky values obtained (from 1.72 to 2.96) indicate the high sensitivity of black pepper to WD. In general, the spikes produced with at least 81 % of the crop water demand were larger and more numerous than those subjected to inferior treatments. WD occurring during the flowering stage severely hampers the size, weight, and quality of the spikes and grains of black pepper.

ABSTRACT. The center of origin and domestication of Piper nigrum L. are in high rainfall regions. But when grown in regions with irregular or insufficient rainfall, irrigation becomes essential. This study evaluated the impact of irrigation levels on the physiological and growth characteristics of black pepper plants, cv. Bragantina. It was carried out from April 2019 to May 2020, using automatic activation irrigation. We used emitters with different flow rates to apply water depths corresponding to 100, 81, 62, and 42% of the crop water requirement. The parameters evaluated comprised main stem length (MSL), stem diameter (SD), number of leaves (NL), leaf area (LA), chlorophyll contents, chlorophyll-a fluorescence, and some photosynthetic parameters. The treatments significantly influenced (p < 0.05, F-test) MSL and NL. Plants submitted to the control treatment showed MSL (65.8%) and NL (123%) greater than those irrigated with the smallest volume (p < 0.05, F-test). However, the treatments had no significant effect on SD. Moreover, chlorophyll b levels decreased by 26% and chlorophyll a/b ratio increased by 22% at 120 and 180 DAT, respectively. Some photosynthetic parameters such as FV/FM, ABS/RC, and DI0/RC were affected by water deficit at 120 DAT. Our results suggest the sensitivity of black peppers to water deficit and contribute to the proper management of this crop.

ABSTRACT Optimization of the use of water and the possibility of using residues as substrate in the black pepper production chain can yield economic and environmental benefits. The objective of this study was to evaluate the biometric and physiological traits of black pepper plantlets (Piper nigrum L.), cv. Bragantina, at different irrigation levels and soilless substrates. Plantlets were grown for 120 days on three substrates [biosolid + crushed coconut fiber (3:1, by volume); biosolid + granitic rock powder (3:1, by volume); and biosolid + crushed coconut fiber + granitic rock powder (2:1:1, by volume)] and at five irrigation levels [36 % (very low); 55 % (low); 85 % (moderate); 100 % (well-irrigated); and 126 % of the reference irrigation level (over-irrigated)]. The biometric traits evaluated increased as the irrigation levels increased, with the exception of root dry mass, which was not influenced by this factor, nor water use efficiency, which decreased as the irrigation levels increased. In general, plants grown with a mixture of the three wastes (biosolid + crushed coconut fiber + granitic rock powder) exhibited higher values for biometric variables and chlorophyll content when they were moderately, well or over-irrigated, in comparison with the other two substrates. It was possible to achieve the plantlet commercial standard using this three waste mixture and the moderate irrigation level.

RESUMO Em razão da quantidade de água utilizada no setor agropecuário, comparada às outras atividades, a irrigação deve ser feita de forma criteriosa e com base no conhecimento das relações hídricas vegetais. O objetivo deste trabalho foi avaliar o comportamento fisiológico de plantas jovens de pimenta-do-reino (Piper nigrum L.), submetidas a restrições hídricas, assim como o potencial de recuperação após o estresse. As plantas, cultivadas em potes de 5 L, foram submetidas a diferentes níveis de irrigação (100; 78; 58 e 32% da lâmina controle), com manejo realizado por acionamento automático a partir de um sensor de tensão da água no solo. Foram avaliados: potencial osmótico foliar (Ψo), conteúdo relativo de água (CRA), condutância estomática (gs) e pigmentos fotossintéticos. Para avaliar a capacidade de recuperação das plantas, houve reidratação do substrato quando cerca de 50% das plantas de um tratamento apresentassem condutância estomática (gs) próxima a zero. Os diferentes níveis de déficit hídrico reduziram os valores de todas as variáveis. No tratamento 32% foram observados valores de −2,39 MPa para Ψo, 60% para CRA e gs próxima a zero no 28º dia de restrição hídrica. Após três dias de reidratação deste tratamento, a recuperação desses valores foi parcial, não atingindo os valores dos tratamentos 100 e 78%. Plantas de pimenta do reino exibiram elevada susceptibilidade a restrições hídricas e baixa capacidade de recuperação após estresse.

ABSTRACT Due to the amount of water used in the agricultural sector, compared to other activities, irrigation must be done carefully and based on knowledge of plant water relations. The aim of this work was to evaluate the physiological behavior of young black pepper plants (Piper nigrum L.), subjected to water deficit, as well as the potential for recovery after stress. In 5 L pots, the plants were subjected to different irrigation levels (100; 78; 58 and 32% of the control depth), with irrigation management performed by an automatic controller from a water tension sensor in the soil. The following traits were evaluated: leaf osmotic potential (Ψo), relative water content (RWC), stomatal conductance (gs) and photosynthetic pigments. To evaluate the plants’ recovery capacity, substrate rehydration was performed when about 50% of the plants in a treatment had stomatal conductance (gs) close to zero. The different levels of water deficit reduced the values of all traits. In the treatment 32%, values of −2.39 MPa for Ψo, 60% for RWC and gs close to zero were observed on the 28 th day of water restriction. After three days of rehydration of this treatment, the recovery of these values was partial, not reaching the values of the treatments 100 and 78%. Black pepper plants showed high susceptibility to water restrictions and low capacity for recovery after stress.

RESUMO A zínia (Zinnia elegans Jacq.) é uma planta de rápido crescimento e fácil cultivo que apresenta flores de variadas colorações. Essa espécie tem se tornado uma opção a ser introduzida comercialmente em vários países como flor de corte e sua qualidade floral é influenciada por diferentes técnicas de cultivo. Neste trabalho, nós avaliamos a produção e a qualidade de hastes florais de zínia (cv. Gigante da Califórnia Vermelha) em resposta a épocas de cultivo e níveis de irrigação. Em casa de vegetação localizada no Rio de Janeiro (Brasil), plantas de zínia foram cultivadas em dois ciclos (outono-inverno e inverno-primavera) em vasos com reposição de água correspondente a 46, 64, 75 e 100% da sua necessidade hídrica. Com base no comprimento e diâmetro de hastes e no diâmetro de flores, houve variação na qualidade das hastes florais produzidas nas épocas de cultivo avaliadas. Todas as hastes do ciclo outono-inverno foram classificadas como A1 (alta qualidade), enquanto, aproximadamente, 9% das hastes do ciclo inverno-primavera foram classificadas como A2 (média qualidade). Houve tendência de crescimento linear na produção e qualidade das hastes florais de zínia com o aumento do nível de irrigação na maioria dos casos, assim como efeito significativo dos ciclos, sendo os melhores resultados de número de hastes, peso fresco, comprimento e diâmetro de haste e diâmetro de flor encontrados no ciclo outono-inverno. As condições meteorológicas deste ciclo favorecem a produção e a qualidade de hastes florais de zínia, e a reposição de 100% da necessidade hídrica da espécie é recomendada em ambos ciclos de cultivo.

ABSTRACT Zinnia (Zinnia elegans Jacq.) is a fast-growing and easy to cultivate plant that has flowers of different colors. This species has become an option to be introduced commercially in many countries as cut flower and its floral quality is influenced by different cultivation techniques. We evaluated the production and the quality of floral stems of zinnia (cv. Red California Giant) in response to growing seasons and irrigation levels. In a greenhouse located in Rio de Janeiro (Brazil), zinnia plants were grown in two cycles (autumn-winter and winter-spring) in pots with water replacement corresponding to 46, 64, 75 and 100% of their water requirement. Based on the stem length and diameter and on the flower diameter, there was variation in the quality of the stems produced in the growing seasons evaluated. All stems from the autumn-winter cycle were classified as A1 (high quality), while almost 9% of the stems from the winter-spring cycle were classified as A2 (medium quality). There was a linear growth trend in the production and quality of zinnia stems with the increase of the irrigation level in most cases, as well as significant effect of the growing seasons, with the best results of number of stems, fresh weight, length and diameter of the stem and flower diameter found in the autumn-winter cycle. The weather conditions of this cycle favor the production and quality of zinnia floral stems, and the replacement of 100% of the specie’s water requirement is recommended in both cultivation cycles.

O conhecimento das precipitações pluviais máximas diárias e seu período de retorno em uma região são características importantes no dimensionamento de trabalhos de conservação de solos, obras hidráulicas, estradas, etc. No entanto, muitos locais não possuem séries históricas adequadas de precipitação, sendo o uso da interpolação geoestatística uma alternativa para a estimativa de dados visando viabilizar a elaboração de mapas de iso-ocorrência. Nesse contexto, o presente trabalho teve como objetivo avaliar a distribuição das precipitações pluviais máximas diárias anuais para diferentes períodos de retorno para o Estado do Rio de Janeiro por meio de técnicas geoestatísticas. As séries de dados foram provenientes de 119 postos pluviométricos, que apresentavam, em média, 36 anos de observações. Para cada estação foi identificada a chuva média máxima diária anual e, em seguida, foram estimados os eventos associados aos períodos de retorno de 2, 5, 10, 25, 50 e 100 anos por meio da distribuição Gumbel. Com esses conjuntos de dados, foram obtidos os modelos experimentais de semivariogramas. Os resultados revelaram que as chuvas associadas aos seus respectivos períodos de retorno apresentaram dependência espacial, com modelo exponencial e esférico ajustados aos semivariogramas experimentais. A precipitação pluvial máxima média diária anual e os eventos associados aos diferentes períodos de retorno tenderam ser maiores de Norte para Sul e do interior para o litoral no Estado. Entre a Serra do Mar e o litoral observou-se, além do aumento na magnitude dos valores, maior variabilidade espacial à medida que se aumentaram os períodos de retorno. O modelo geoestatístico foi mais errático para maiores períodos de retorno, e para as regiões Norte, Noroeste e da Baixada Litorânea, sendo estes locais recomendados para a instalação de novas estações pluviométricas.

Knowledge of maximum daily rain and its return period in a region is an important tool to soil conservation, hydraulic engineering and preservation of road projects. The objective of this work was to evaluate the spatial variability of maximum annual daily rain considering different return periods, at the Rio de Janeiro State. The data set was composed by historical series of 119 rain gauges, for 36 years of observation. The return periods, estimated by Gumbel distribution, were 2, 5, 10, 25, 50 and 100 years. The spatial variability of the return periods was evaluated by semivariograms. All the return periods presented spatial dependence, with exponential and spherical model fitted to the experimental semivariograms. The parameters of the fitted semivariogram model were very similar; however, it was observed the presence of higher nugget effects for semivariograms of longer return periods. The values of maximum annual daily average rain in all the return periods increased from north to south and from countryside to the coast. In the region between the Serra do Mar range and the coast, besides increasing in magnitude, an increase in the spatial variability of the studied values with increasing return periods was also noticed. This behavior is probably caused by the orographic effect. The interpolated maps were more erratic for higher return periods and at the North, Northeast and Coastal Plain regions, in which the installation of new pluviometric stations are recommended.