Differential effect of elevated carbon dioxide on sucrose transport and accumulation in developing grains of three rice cultivars

Abstract

To study the effect of high CO2 environment on grain filling of rice (Oryza sativa L.), plants were exposed to different environments: ambient (CO2 ~ 390 ppm) and elevated CO2 (CO2 ~ 490 ppm) throughout the growing period during wet season (2012 and 2013) in subtropical India. The experiment was conducted in open top chambers with three indica rice cultivars (Badshabhog, IR36 and Swarna) of varying duration and yield potential. Grain yield of selected rice cultivars (IR36 & Swarna) declined by 12%, but increased by 8% for Badshabhog, with increasing CO2 (+100 ppm) and air temperature (+1 °C) above the ambient value. Interestingly our analysis during rice grain filling period with CO2 elevation revealed significant reduction of OsSUT1 gene expression in the flag leaf and grain of IR36 (52% and 95.7%, respectively) and Swarna (58.5% and 89.6%, respectively). However, the expression of OsSUT1 gene in Badshabhog remained mostly unaffected under CO2 elevation. Further, the non-reducing sugar content decreased in grain tissues of IR36 and Swarna at 14 and 21 days after flowering, respectively; but not in Badshabhog with elevated CO2. Together, this study shows that there is scope for genotype-dependent yield improvement by selective breeding or transgenic technology under elevated CO2 condition.