Interactive effect of elevated tropospheric ozone and carbon dioxide on radiation utilisation, growth and yield of chickpea (Cicer arietinum L.).

An experiment was conducted in the Free Air Ozone and Carbon dioxide Enrichment (FAOCE) facility to study the impact of elevated O, CO and their interaction on chickpea crop (cv. Pusa-5023) in terms of phenology, biophysical parameters, yield components, radiation interception and use efficiency. The crop was exposed to elevated O (EO:60ppb), CO (EC:550 ppm) and their combined interactive treatment (ECO: EC+EO) during the entire growing season. Results revealed that the crop's total growth period was shortened by 10, 14 and 17 days under elevated CO, elevated O and the combined treatment, respectively. Compared to ambient condition, the leaf area index (LAI) under elevated CO was higher by 4 to 28%, whilst it is reduced by 7.3 to 23.8% under elevated O. The yield based radiation use efficiency (RUE) was highest under elevated CO (0.48 g MJ), followed by combined (0.41 g MJ), ambient (0.38 g MJ) and elevated O (0.32 g MJ) treatments. Elevated O decreased RUE by 15.78% over ambient, and the interaction results in a 7.8% higher RUE. The yield was 31.7% more under elevated CO and 21.9% lower in elevated O treatment as compared to the ambient. The combined interactive treatment recorded a higher yield as compared to ambient by 9.7%. Harvest index (HI) was lowest under elevated O (36.10%), followed by ambient (39.18%), combined (40.81%), and highest was under elevated CO (44.18%). Chickpea showed a positive response to elevated CO resulting a 5% increase in HI as compared to ambient condition. Our findings quantified the positive and negative impacts of elevated O, CO and their interaction on chickpea and revealed that the negative impacts of elevated O can be compensated by elevated CO in chickpea. This work promotes the understanding of crop behaviour under elevated O, CO and their interaction, which can be used as valuable inputs for radiation-based crop simulation models to simulate climate change impact on chickpea crop.