Transpiration of young cocoa trees under soil water restriction

Cocoa plantations in Brazil have been expanding beyond the borders of traditional regions by implementing a strategy based on irrigation and the establishment of crops exposed to full sunlight. The quantification of transpiration is essential to the establishment and management of crops, and is the main factor in the determination of water demand. This study had as its objective the estimating of transpiration of young cocoa trees as a function of reference evapotranspiration (ETo) and soil matric potential (Ψw). Two experiments were conducted, one in a greenhouse and the other in the field, using clones and seminal plants. Soil water content, plant transpiration and reference evapotranspiration were monitored. Cocoa trees were subjected to soil moisture reduction and their transpiration decreased linearly both in the field and in the greenhouse, due to decreases in the soil matric potential beyond a critical point. In the greenhouse average transpiration could be linearly estimated as a function of ETo when Ψw was higher than –24.89 kP. Drying soil conditions resulted in a reduction in transpiration by approximately a 2 % per unit decrease in Ψw. Under field conditions; clonal plant transpiration decreased linearly beyond the critical matric potential of –65.02 kPa, while in seminal plants this reduction occurred beyond –79.48 kPa. Clonal plants were more sensitive to soil water variations with average transpiration lower than that of seminal cocoa tree plants.

Transpiration of young cocoa trees under soil water restriction

Cocoa plantations in Brazil have been expanding beyond the borders of traditional regions by implementing a strategy based on irrigation and the establishment of crops exposed to full sunlight. The quantification of transpiration is essential to the establishment and management of crops, and is the main factor in the determination of water demand. This study had as its objective the estimating of transpiration of young cocoa trees as a function of reference evapotranspiration (ETo) and soil matric potential (Ψw). Two experiments were conducted, one in a greenhouse and the other in the field, using clones and seminal plants. Soil water content, plant transpiration and reference evapotranspiration were monitored. Cocoa trees were subjected to soil moisture reduction and their transpiration decreased linearly both in the field and in the greenhouse, due to decreases in the soil matric potential beyond a critical point. In the greenhouse average transpiration could be linearly estimated as a function of ETo when Ψw was higher than –24.89 kP. Drying soil conditions resulted in a reduction in transpiration by approximately a 2 % per unit decrease in Ψw. Under field conditions; clonal plant transpiration decreased linearly beyond the critical matric potential of –65.02 kPa, while in seminal plants this reduction occurred beyond –79.48 kPa. Clonal plants were more sensitive to soil water variations with average transpiration lower than that of seminal cocoa tree plants.(AU)

Crescimento vegetativo do quiabeiro em função da salinidade da água de irrigação e da adubação nitrogenada / Vegetative growth of okra in function of water salinity and nitrogen fertilization

O objetivo do trabalho foi avaliar o desenvolvimento vegetativo e produção de matéria seca do quiabeiro submetido a diferentes níveis de salinidade da água de irrigação e diferentes doses de adubação nitrogenada. O experimento foi conduzido em casa de vegetação, na Universidade Federal do Recôncavo da Bahia, no município de Cruz das Almas, BA. O delineamento experimental foi inteiramente casualizado em esquema fatorial 5 x 4, com três repetições. Foram testados cinco níveis de salinidade da água de irrigação (0,26; 1,0; 2,0; 4,0 e 5,0 dS.m -1 ) e quatro doses de nitrogênio (50, 75, 100 e 125 % da dose indicada para ensaios em vaso), provenientes da combinação entre uréia e nitrato de potássio. Foram analisadas as seguintes variáveis: altura de plantas, diâmetro do caule, número de folhas e matéria seca de folhas, ramos e raízes. Os dados obtidos foram submetidos à análise de variância e de regressão os quais foram ajustados modelos polinomiais. Não houve correlação entre as doses de nitrogênio aplicadas e a matéria seca do caule e das raízes, sendo significativo apenas para a matéria seca das folhas. A altura e o diâmetro do caule do quiabeiro apresentaram uma resposta negativa ao aumento da salinidade da água aplicada. A interação entre os níveis de salinidade e as doses de nitrogênio testadas não foi significativa para a matéria seca de folhas, ramos e raízes do quiabeiro. O aumento da salinidade da água de irrigação resultou na redução na matéria seca de folhas, caules e raízes na cultura do quiabeiro.

The objective of present work was to evaluate okra plants in respect to the vegetative development and production of dry matter, subjected to different levels of salinity of irrigation water and different doses of nitrogen fertilization in greenhouse. The experiment was conducted in a greenhouse at to the Federal University of Bahia Reconcavo, in Cruz das Almas, BA. The experimental design was completely randomized in a 5 x 4 factorial scheme, with three replications. Five levels of irrigation water salinity were tested (0.26; 1,0; 2,0; 4,0 and 5,0 dS.m -1 ) and four nitrogen rates (50, 75, 100 and 125% of the rate recommended for potted experiments), from the combination of urea and potassium nitrate. The following variables were analyzed: plant height, stem diameter, number of leaves and dry matter of leaf, branches and roots. The data were submitted to analysis of variance and regression which were fitted to polynomial models. There was no correlation between the levels of nitrogen applied and the dry weight of shoots and roots, but only significantly for dry matter of leaves. The plant height and the okra the stem diameter showed a negative response to increased salinity of water applied. The interaction between salinity levels and tested nitrogen rates was not significant for biomass of leaf, branches and of okra plants roots. The increasing salinity irrigation water resulted in the dry matter of leaves, stems and roots in plants okra.

Crescimento vegetativo do quiabeiro em função da salinidade da água de irrigação e da adubação nitrogenada / Vegetative growth of okra in function of water salinity and nitrogen fertilization

O objetivo do trabalho foi avaliar o desenvolvimento vegetativo e produção de matéria seca do quiabeiro submetido a diferentes níveis de salinidade da água de irrigação e diferentes doses de adubação nitrogenada. O experimento foi conduzido em casa de vegetação, na Universidade Federal do Recôncavo da Bahia, no município de Cruz das Almas, BA. O delineamento experimental foi inteiramente casualizado em esquema fatorial 5 x 4, com três repetições. Foram testados cinco níveis de salinidade da água de irrigação (0,26; 1,0; 2,0; 4,0 e 5,0 dS.m -1 ) e quatro doses de nitrogênio (50, 75, 100 e 125 % da dose indicada para ensaios em vaso), provenientes da combinação entre uréia e nitrato de potássio. Foram analisadas as seguintes variáveis: altura de plantas, diâmetro do caule, número de folhas e matéria seca de folhas, ramos e raízes. Os dados obtidos foram submetidos à análise de variância e de regressão os quais foram ajustados modelos polinomiais. Não houve correlação entre as doses de nitrogênio aplicadas e a matéria seca do caule e das raízes, sendo significativo apenas para a matéria seca das folhas. A altura e o diâmetro do caule do quiabeiro apresentaram uma resposta negativa ao aumento da salinidade da água aplicada. A interação entre os níveis de salinidade e as doses de nitrogênio testadas não foi significativa para a matéria seca de folhas, ramos e raízes do quiabeiro. O aumento da salinidade da água de irrigação resultou na redução na matéria seca de folhas, caules e raízes na cultura do quiabeiro.(AU)

The objective of present work was to evaluate okra plants in respect to the vegetative development and production of dry matter, subjected to different levels of salinity of irrigation water and different doses of nitrogen fertilization in greenhouse. The experiment was conducted in a greenhouse at to the Federal University of Bahia Reconcavo, in Cruz das Almas, BA. The experimental design was completely randomized in a 5 x 4 factorial scheme, with three replications. Five levels of irrigation water salinity were tested (0.26; 1,0; 2,0; 4,0 and 5,0 dS.m -1 ) and four nitrogen rates (50, 75, 100 and 125% of the rate recommended for potted experiments), from the combination of urea and potassium nitrate. The following variables were analyzed: plant height, stem diameter, number of leaves and dry matter of leaf, branches and roots. The data were submitted to analysis of variance and regression which were fitted to polynomial models. There was no correlation between the levels of nitrogen applied and the dry weight of shoots and roots, but only significantly for dry matter of leaves. The plant height and the okra the stem diameter showed a negative response to increased salinity of water applied. The interaction between salinity levels and tested nitrogen rates was not significant for biomass of leaf, branches and of okra plants roots. The increasing salinity irrigation water resulted in the dry matter of leaves, stems and roots in plants okra.(AU)