Adaptation to Heat and Drought Stresses in Snap Bean (Phaseolus vulgaris) during the Reproductive Stage of Development

Abstract

We screened snap bean (Phaseolus vulgaris L.) germplasm for heat and drought tolerance during the reproductive stage under extremely hot conditions as well as in the winter seasons in closed net houses to raise the temperatures under field conditions, a practice usually followed by vegetable growers. Substantial genotypic differences were found in morpho-physiological characteristics like phenology, plant water relations, photosynthetic parameters and shoot growth, which were related to the reproductive responses. The associations of days to podding and leaf water content with the number of pods per plant and seed yield were consistent across the different environments and experiments. The leaf water content was maintained by reductions in leaf water potential and shoot extension in response to heat and drought stress. Therefore, these traits can be used as a marker to screen germplasm for heat and drought tolerance. In this paper, we briefly reviewed the results of our studies carried out on heat and drought tolerance in snap bean at Okinawa Subtropical Station, Ishigaki.