Cowpea Ecophysiological Responses to Accumulated Water Deficiency during the Reproductive Phase in Northeastern Pará, Brazil

Cowpea (Vigna unguiculata (L.) Walp.) is a leguminous species widely cultivated in northern and northeastern Brazil. In the state of Pará, this crop still has low productivity due to several factors, such as soil fertility climatic adversity, especially water deficiency. Therefore, present study aimed at evaluating physiological parameters cowpea plants under different depths. The experiment was conducted Castanhal/Pará between 2015 2016. A randomized block design applied with six replications four treatments, represented by replacement 100%, 50%, 25% 0% lost during evapotranspiration (ETc), starting from reproductive stage. rates net photosynthesis (A), stomatal conductance (gs), leaf transpiration (Eleaf), substomatal CO2 concentration (Ci), temperature (Tleaf) potential (Ψw) were determined measurements R5, R7, R8 R9 phenological stages. sensitive availability soil, showing significant difference treatments for variables productivity. Upon reaching Ψw equal −0.88 MPa, studied showed important changes, which allows establishing value threshold regarding stress experimental conditions. levels directly influenced both years, indicating that proper supply leads better growth development, increasing