Physiological responses, yield and seed quality of dry bean submitted to drought stress

The global photosynthesis, respiration, yield, and physical and physiological quality of dry bean seeds of the variety "Short season Black Bean" from the Mixteca Alta of Oaxaca, Mexico, were evaluated in plants subjected to drought stress during the pod formation (PFS) and seed filling (SFS) stages. During SFS the global photosynthesis in the upper leaves decreased from 21.5 to -4.5 mu mol(.)m(-2.)s(-1) CO2 after 5 days under water stress, and in the lower leaves a total inhibition was observed at day 3. The pods from plants subjected to water stress showed a reduction of global photosynthesis of 39 and 72% in the upper and lower stratum of the plant, respectively. Drought stress induced seed yield reductions of 23 and 18% for PFS and SFS respectively. In PFS the reduction of yield was due to the attenuation of 30, 15.5 and 15.4% in seed number, pods per plant and. seed per pod, respectively. In SFS the yield reduction-was due to a decrease of 23 and 13% on seed size and seed number per plant., Germination, seedling dry matter, and volumetric, see weight were not affected by stages; however, the seed vigor the imposed drought stress in both stages was decreased due to a 46% increase in electrical conductivity in seeds from plant subjected to drought stress during SFS.