A study on elevated carbon dioxide (eCO<sub>2</sub>), elevated temperature (eT) and their interactive effect on chickpea (<i>Cicer arietinum</i> L.) yield and seed mineral nutrients

Continuously increasing carbon dioxide concentration is predicted to elevate the earth’s temperature. Elevated temperature is a severe problem for the cultivation of chickpea (Cicer arietinum L ). Therefore, the present study aimed to assess the effect of elevated carbon dioxide (eCO2), elevated temperature (eT) and their interactive effect on yield and seed mineral nutrients of two genotypes, i.e., ICC 4958 (desi) and Flip 90-166 (kabuli) of chickpea (C. arietinum L ). The pot experiments were conducted in Open Top Chamber (OTC) for two consecutive years (2019-20 and 2020-21), along with the control placed in ambient natural conditions. The eCO2 (650±50 µl/l) and eT (~4oC) were given individually and in combination. The gaseous exchange was measured at the flowering stage. After harvesting, yield and its parameters, seed protein and mineral nutrients were determined using standard methods. Under eCO2, the photosynthesis of both genotypes was positively affected, ultimately converting to yield (8.8-17.5% increase). However, the effect was more prominent in ICC 4958 than Flip 90-166. Higher temperature only positively affected dry biomass, but that effect was not converted to yield; instead, a reduction occurred in yield (- 12.0 to -26.9% ). In combination with eCO2 and eT, the negative effect of high temperature was ameliorated by eCO2 on yield, augmenting the effects on seed nutrient reduction. Among the seed mineral nutrients, Na, K, Fe and Zn were most reduced (-20.3 to -30.0%) under interactive effect. The findings will help to enhance seed yield with improved mineral nutrient content of chickpea.