Relationship between carbon isotope discrimination, ash content and grain yield in wheat in the Peninsular Zone of India

Carbon isotope discrimination (Delta) and ash content (m(a)) have been proposed as indirect selection criteria for grain yield in wheat. The associations between Delta, m(a) and grain yield were found, however, to depend highly on the environmental conditions, the organ sampled and the time of sampling. In this study, carried out in the warm conditions of the Peninsular Zone of India, the relationship between Delta, m(a) and yield was studied in 30 bread and durum wheat cultivars under residual soil moisture stress (RSMS), post-anthesis water stress (PAWS) and well-watered (WW) conditions. Both Delta and m(a) were analysed in young seedlings (four-leaf stage), leaves at anthesis and grain at maturity. Ash content was also evaluated in leaves at booting stage and maturity. Grain Delta was lower under PAWS and RSMS than under WW, while seedling and leaf Delta did not significantly differ among water regimes. Grain yield was positively correlated to grain Delta under PAWS and negatively correlated to grain m(a) under RSMS. A significant positive correlation was noted under RSMS and WW treatments between m(a)L(m) and grain yield. Ash content in leaf at maturity consequently appears to be a useful indirect selection criterion in environments where Delta does not show any correlation with yield. The results highlight the potential of Delta and m(a) as indirect selection criteria for wheat yield in the conditions of the Peninsular Zone of India.