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The mechanisms affecting the heat sensitivity of chickpea are largely unknown. Heat-tolerant (ICCV07110, ICCV92944) and heat-sensitive (ICC14183, ICC5912) chickpea genotypes were sown in February in the soil-filled pots. At the time of flowering, these were subjected to varying day/night temperatures of 30/20, 35/25, 40/30 and 45/358C in the growth chambers (12 h light/12 h dark; light intensity, 250 mmol m 72 s 71 , 80% relative humidity). The pollen viability, pollen germination, tube growth, pollen load and stigma receptivity decreased with increases in temperatures to 45/358C. The heat-tolerant genotypes experienced significantly less damage to pollen and stigma function. Membrane integrity, chlorophyll content, photochemical efficiency and cellular oxidizing ability were inhibited by the increase in temperature, with greater impacts on the sensitive genotypes. Oxidative injury as lipid peroxidation and hydrogen peroxide content was significantly greater in sensitive genotypes at 40/30 and 45/358C. Enzymatic and non-enzymatic antioxidants showed increased levels at 40/308C, but decreased considerably at 45/358C. Heat-tolerant genotypes possessed greater activity of ascorbate peroxidase and glutathione reductase, along with higher levels of ascorbate and reduced glutathione at 40/30 and 45/ 358C. Biomass, pod set and yield were not affected significantly at 35/258C, but began to decrease at 40/308C and were lowest at 45/358C. The sensitive genotypes were not able to set any pods at 45/358C, whereas the tolerant genotypes produced only few fertile pods at this temperature. It was concluded that heat stress leads to loss of pollen as well as stigma function and induces oxidative stress in the leaves that cause failure of fertilization and damage to the leaves, respectively.

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Chilling stress (\10°C) at reproductive phase of chickpea results in abortion of flowers and pods leading to poor yield. The metabolic causes associated with cold sensitivity of chickpea are not well understood. Hence, in the present study, we evaluated four chickpea genotypes (ICC 16348, ICC 16349, PBG1 and GPF2) having contrasting cold sensitivity for their reproductive growth and metabolism subjected to cold stress (average day temperature: 17.6°C; average night temperature: 4.9°C). Genotypes ICC 16348 and ICC 16349 showed flowering and set pods, while PBG1 and GPF2 failed to do so during the stress conditions indicating the former to be cold tolerant. The stress injury in the leaves such as increase in electrolyte leakage, decrease in chlorophyll content and relative leaf water content was significantly less in ICC 16348 and ICC 16349 genotypes. The analysis of carbohydrates indicated total sugars and starch to be present in greater content in ICC 16348 and ICC 16349 relative to PBG1 and GPF2 genotypes. The enzymes related to carbohydrate metabolism such as b-amylase, invertase and sucrose synthase showed significantly higher activity in the leaves of ICC 16348 and ICC 16349 compared to the other two genotypes. PBG1 and GPF2 genotypes experienced greater oxidative stress measured as malondialdehyde and hydrogen peroxide. ICCV 16348 and ICC 16349 possessed significantly higher levels of enzymatic (superoxide dismutase, catalase, ascorbate peroxidase) and non-enzymatic antioxidants (proline and ascorbic acid) relative to PBG1 and GPF2. Particularly, proline and ascorbic acid were markedly higher in cold-tolerant genotypes compared to the sensitive ones suggesting their deciding role in governing the cold tolerance.