PHYSIOLOGICAL PERFORMANCE, YIELD, AND QUALITY OF DRY BEAN SEEDS UNDER DROUGHT STRESS

Net photosynthesis (A), respiration (RE), stomatal conductance (gs), transpiration rate (E), yield, and its components, as well as physical and physiological quality of seeds were evaluated on dry bean (Phaseolus vulgaris L.) plants cv. 'Otomi', subjected to drought stress during the stages of flowering (F), pod formation (PF) and seed filling (SF). After 3 days under drought stress, gs, E and A decreased by more than 50% at F PF and SF respectively; after 10 days of stress, there was total inhibition of those processes, whereas the maximum reductions showed by RE were 42, 62, and 85% in F, PF and SF respectively. Drought stress induced seed yield reductions of 10, 57, and 50% at F PF and SF respectively. High yield losses at PF and SF were caused by reductions in the number of seeds and pods per plant and seeds per pod. At the SF stage the loss in yield was moderate, because at this stage the plants were able to form new leaves and delay pod formation until water stress was over The physiological quality was not affected by drought stress, even though the weight of 1000 seeds was reduced by about 10%.