Field response of chickpea (Cicer arietinum L.) to high temperature
High temperature is an important factor affecting chickpea growth, development and grain yield. Understanding the plant response to high temperature is a key strategy in breeding for heat tolerance in chickpea (Cicer arietinum L.). This study assessed genetic variability for heat tolerance in chickpea and identified sources of heat tolerance that could be used for crop improvement. One hundred and sixty-seven genotypes were grown in two environments (heat stressed/late sown and non-stressed/optimal sowing time) in 2 years (2009–2010 and 2010–2011) at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India. Large genetic variation was observed for phenology, growth, yield components and grain yield. While phenology (assessed as days to first flower, days to 50% flowering and days to first pod) was negatively correlated with grain yield at high temperature; plant biomass, pod number, filled pod number and seed number per plant were positively correlated. Genotypes were classified into short and long duration groups based on their maturity. Days to first flowering (DFF) of long duration genotypes were negatively associated with grain yield under stressed conditions in both years compared with medium to short duration genotypes. However, genotypes varied in their heat sensitivity and temperatures ≥35 °C produced yield losses up to 39%. A heat tolerance index (HTI) classified the genotypes into five groups: (i) stable heat tolerant (>0.5), (ii) moderately heat tolerant (0.1–0.49), (iii) stable heat sensitive (−ve values), (iv) heat tolerant to moderately sensitive (−0.10 to 1) and (v) heat sensitive to moderately tolerant (−0.5 to 0.4). Pod characteristics, including days to first pod and pod number per plant, were correlated with grain yield whereas canopy temperature depression (CTD) was generally not correlated. Heat tolerant genotypes in a range of maturities were identified that could be used to improve the heat tolerance of chickpea.