Effects of elevated [CO2] on stem and root lodging among rice cultivars

Studies showed that elevated [CO2] would improve photosynthetic rates and enhance yields of rice; however, few studies have focused on the response of rice lodging, which is a major cause of cereal yield loss and quality reduction, under elevated [CO2]. In this study, we examined the effects of elevated [CO2] on stem and root lodging using 4 rice cultivars (86Y8, japonica hybrid; LYP9, 2-line indica hybrid; variety 9311, type of indica inbred rice, and SY63, 3-line indica hybrid) grown under two [CO2] levels: 400 and 680 μmol mol 1. Our results indicated that under elevated [CO2], the stem-lodging risk (SLR) of 9311 decreased, while in SY63 the SLR increased, 86Y8 and LYP9 were not significantly affected; the risk of root lodging was reduced for all cultivars, because root biomass (instead of root number) and bending strength were increased significantly, and then the increase of anti-lodging ability is far higher than that of self-weight mass moment for all cultivars. These findings suggested that higher [CO2] can enhance the risk of stem-lodging for cultivars with strong-[CO2]-responses, but may not aggravate the root lodging for all rice cultivars.