Interactive effect of irrigation and temperature regimes on growth and development of kidney bean (Phaseolus vulgaris L.)

Approximately 60 percent of kidney bean (Phaseolus vulgaris L.) produced in developing countries is cultivated under conditions of drought stress and low fertility/ low input. Coincidence of water and heat stress, which is projected to occur more in changing climates, cause severe yield loss. To quantify the response of kidney bean to water and temperature stress, an experiment was carried under Randomized Block Design in field and temperature gradient tunnel conditions. Temperature treatments included high temperature for entire crop growth period (~4.6℃, ~3.1℃, ~2.8℃  above mean ambient, 19.6℃), ambient temperature,  elevated temperature during pre-flowering phase (~3.7℃ above mean ambient during that period, 19.6℃), flowering phase (~5.3℃ above mean ambient during that period, 23.1℃) and pod-filling phase (~5.2℃ above mean ambient during that period, 28.9℃). These were combined with i) two irrigations (applied at sowing and seedling phase) and ii) three irrigations (additional irrigation at pod-filling phase). Results indicated that plants under seasonal mean temperatures of 36.7/11.7℃, 33.9/11.6℃ and 33.1/11.7℃ had shortened crop duration with 73-78 DAS. Findings this study indicated that kidney bean exhibits phenological plasticity response to temperature and water regimes. Seasonal mean temperature of 24.2℃ lead to better performance of the crop while temperature shocks during pre-flowering and flowering significantly reduced seed yield. Additionally, exposure of kidney bean plants to water stress (available soil moisture content <10%) significantly reduced seed yield. Coincidence of temperature stress and water stress had more detrimental effects on seed yield. Given the climate scenarios indicating increased variability in temperature and rainfall, findings from this study indicate that climatic risks mayaffect kidney bean seed yield in future. Strategies such as providing supplemental irrigation can alleviate the negative effects of temperature stress and improve kidney bean yield.