PHYSIOLOGICAL RESPONSES OF COWPEA UNDER WATER STRESS AND REWATERING IN NO-TILLAGE AND CONVENTIONAL TILLAGE SYSTEMS ¹

RESPOSTAS FISIOLÓGICAS DE FEIJÃO-CAUPI SOB ESTRESSE HÍDRICO E REIDRATAÇÃO EM PLANTIO DIRETO E CONVENCIONAL

ABSTRACT

The goal of this work was to evaluate the physiological responses of cowpea under water stress and rehydration in conventional and no-tillage systems. We evaluated two crop systems (conventional and no tillage) and three water conditions (no stress, moderate stress and severe stress). The following were determined: leaf area, total dry matter, photosynthetic rate, stomatal conductance, transpiration rate, internal CO2 concentration and leaf water potential. Water stress affected all variables evaluated, with the exception of leaf water potential. Cowpea recovered with respect to all variables after rehydration at both stress levels. Stomatal closure is an important drought tolerance mechanism, and cowpea can be considered a conservative species (i.e., one that prioritizes water status maintenance rather than photosynthetic rate). Planting systems did not affect photosynthetic rate. The tillage system promoted greater accumulation of biomass and higher leaf area.

Keywords:
Leaf area; Photosynthesis; Stomatal conductance; Vigna unguiculata; Water potential.