Atmospheric carbon dioxide enrichment induced modifications in canopy radiation utilization, growth and yield of chickpea [Cicer arietinum L.)]

• Elevated CO2 produced higher biomass and thicker leaves in chickpea.
• Leaf area index, leaf C:N ratio also increased with CO2.
• Radiation use efficiency increased with stable harvest index value.
• Wide C:N ratio indicates low grain quality in chickpea with elevated CO2.

Open top chamber experiments were conducted to study the response of chickpea crop (cv. Pusa-1105) to atmospheric CO2 enrichment at 580 ± 20 ppm, in terms of radiation interception and use efficiency, biophysical parameters and yield components. The ambient (control) was kept at 384 ± 13 ppm. A significant increase in leaf area index was recorded through CO2 enrichment, while no change in fractional intercepted photosynthetically active radiation was observed. This might be due to significant reduction (18.5%) in the canopy extinction coefficient. A 24% increase in radiation use efficiency resulted in 27.3% higher crop biomass. The specific leaf nitrogen content was higher although there was a reduction in specific leaf area, indicating increase in laminar thickness under enriched atmospheric CO2 environment. Greater water soluble carbohydrate concentration in leaves suggests greater C assimilation under enriched atmospheric CO2, with wide leaf C:N ratio at 50% flowering. There was no significant change in harvest index, but larger C:N in grains indicated reduction in the quality of grains. We conclude that a significant increase in chickpea productivity under enriched CO2 will occur, although at the cost of reduction in nutritional quality of the produce.

Site of the experimentation (A1 and A2 = enriched, and B1 and B2 = ambient CO2 treatment) (inset: C = temperature and D = CO2 sensor installed inside the chambers).Figure optionsDownload as PowerPoint slide