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

Abstract

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) CO 2 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 CO 2 significantly increased the photosynthetic rate (A net), decreased the transpiration rate and increased water use efficiency (WUE). Higher impact of elevated CO 2 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 CO 2 ; 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 CO 2 as compared with reproductive biomass and influencing the harvest Index (HI).

Potential effects of a high CO2 future on leguminous species

“…To further complicate matters, environmental factors appear to play a substantial role in seed yield effects under e[CO 2 ], which is evidenced by the finding that smaller stimulations in yield are typically observed in FACE experiments compared to those conducted in controlled environments (Ainsworth et al, 2008 ). Furthermore, a large amount of intraspecific variability is evident in legume species with respect to the magnitude of yield gains under e[CO 2 ] (Bishop et al, 2015 ; Bunce, 2016 ; Kumagai et al, 2015 ; Li et al, 2017 ; Li et al, 2019 ; Vanaja et al, 2015 ). Intriguingly, it has been found that soybean cultivars displaying the greatest yield increases under CO 2 enrichment were not necessarily those with the highest yields under ambient [CO 2 ], but instead those that displayed the greatest yield gain under e[CO 2 ] (Li et al, 2017 ; Li et al, 2019 ).…”