Respostas fisiológicas do feijão-caupi submetidos a restrição hídrica e aplicação de óxido de cálcio sobre as folhas

Abstract

Cowpea is an African origin of fabaceae largely grown in the north and northeast region of Brazil, which stands out as the main protein source for the needy populations of these regions, and generate jobs and income. Being a C3 plant and have short vegetative growth, it is very sensitive to competition from weeds, the essential factors like light, and especially to use water for its development. The solar radiation can be considered a very important factor for plant growth and development, since it directly influences the photosynthesis of the plants. Thus, the aim of this study was to evaluate the effects of application of calcium oxide (CaO) in cowpea leaves submitted or not to water stress in order to optimize gas exchange and increase efficiency in water use these plants. The work was conducted in the experimental field of the Federal University of Sergipe, in São Cristóvão - SE. The treatments were performed: 1 control 50% [50% replacement of the reference evapotranspiration (Eto)]; 2- control 100% (100% replacement of evapotranspiration); 3- suspension of 5% CaO + 50% Eto; 4- suspension of 10% CaO + 50% Eto; 5- suspension of 5% CaO +% ETO 100; 6- suspension of 10% CaO + 100% ETO. The plants were sprayed three times at the beginning, middle and end of the experiment and were evaluated (A), stomatal conductance (gs), transpiration (E), steam pressure Deficit (VPD), the water use efficiency (A / Gs and A / E) and chlorophyll a and b. The experimental design was randomized blocks in a factorial scheme (6x3), and (6 treatments and 3 times). The experimental results were submitted to analysis of variance and the means compared by Scott Knot test at 5% significance. The results showed that the particle film to 10% of CaO concentration was 50% efficient to reduce the use of water, keeping the variables (A, Gs, E and chlorophylls) the same treatment without water restriction.