Physiological Response of Common Bean (Phaseolus vulgaris L.) to Varying Temperature and Irrigation Regimes

Background: Elevated temperature and water stress are the key limiting factors affecting the kidney bean yield. Climate change is projected to enhance these risks for successful crop production. However quantified information, which is limited, on temperatures stress at various growth phases in combination with water regimes, becomes important for optimizing management decisions for higher productivity of kidney bean. The current study is aimed to fill this gap. Methods: A field experiment was conducted during January-April 2020, to investigate the effect of irrigation and temperature regimes on growth parameters and yield of kidney bean. Temperature treatments imposed were elevated temperature for entire crop period i)-4.6 & DEG;C ii)-3.1 & DEG;C iii)-2.8 & DEG;C above mean ambient (19.6 & DEG;C), iv) ambient temperature Tmax and Tmin regime of 25.9/13.4 & DEG;C (mean 19.6 & DEG;C), v) elevated temperature during pre-flowering phase (-3.7 & DEG;C above mean ambient during that period, 19.6 & DEG;C), vi) flowering phase (-5.3 & DEG;C above mean ambient during that period, 23.1 & DEG;C) and pod-filling phase (-5.2 & DEG;C above mean ambient during that period, 28.9 & DEG;C). These were combined with i) two irrigations (applied at sowing and seedling phase) and ii) three irrigations (additional irrigation at pod-filling phase). Result: Elevated temperature regimes led to shortening of the crop duration. LAI, NDVI, net photosynthesis and seed yield were higher in plants exposed to continuous elevated temperature. Heat shock during pre-flowering and flowering led to reduction in yield. Despite exposure to elevated temperature, supplemental irrigation led to higher yield. Seed yield loss was greater when temperature stress coincided with water stress. The negative effects of high temperature were significantly curtailed by provision of supplemental irrigation.