Genotypic variation in carbon fixation, δ13C fractionation and grain yield in seven wheat cultivars grown under well-watered conditions

Biotic carbon (C) sequestration is currently being considered as a viable option for mitigating atmospheric carbon dioxide (CO2) emission, in which photosynthesis plays a significant role. A field experiment was conducted between 2013 and 2015 to investigate the efficiency of seven modern wheat varieties for CO2 fixation, C partitioning, δ13C fractionation in the leaves, and grain yield. A strong correlation between flag leaf photosynthesis and stomatal density (r = 0.891) was detected. Photosynthetic efficiency was highest in the variety WH-1021 (28.93 µmol m–2 s–1). Grain yield was influenced by biomass accumulation in the heads and these were significantly correlated (r = 0.530). Our results show that upregulated biomass partitioning to the developing kernels of wheat was inversely proportional to biomass accumulation in the roots, and led to a higher grain yield. These results led us to conclude that identification of a wheat genotype like WH-1021 followed by WH-1080 and WH-711, with higher isotopic discrimination in the flag leaves, stomatal densities, water use and photosynthetic efficiencies along with higher grain yield, can contribute to sustainable agriculture in future climate change situation in India. A yield increment of 9–48% was recorded in WH-1021 over other six tested wheat varieties.