Variability in Phenology, Physiology and Yield Response of Different Maturity Duration Pigeon Pea Genotypes at Elevated CO2

Three pigeon pea (Cajanus cajan L. Millsp.) genotypes-ICPL-88039, GT-1, and AKP-1-with varying crop duration, growth habit and flowering pattern were grown at ambient (390 ppm) and elevated (550 ppm) CO2 levels in Open Top Chambers (OTCs) to assess the variability in their responses for phenology, physiology, biomass and seed yield parameters. It was observed that elevated CO2 significantly increased the photosynthetic rate (Anet), decreased the transpiration rate and increased water use efficiency (WUE). Higher impact of elevated CO2 on the earliness of flowering was observed as the duration of the genotype was increased. 50% flowering at 550 ppm was early by 1.3 days in ICPL-88039 and 12 days in GT-1 and 20 days in AKP-1 as compared with ambient. All the selected genotypes improved their biomass and seed yield with elevated CO2; however, the response of individual component and magnitude of the response was genotype specific. As the duration of the pigeon pea genotypes was increasing from extra-short to short and short-medium, the response of vegetative biomass was increasing under elevated CO2 as compared with reproductive biomass and influencing the harvest Index (HI).