Physiological Mechanism of Drought-Resistant Rice Coping With Drought Stress

Drought stress is one of the major threats to rice production. The weakening leaf photosynthesis due drought main reason for reduction grain yield, but its mechanism still obscure. objectives this study were reveal physiological affecting photosynthetic capacity and yield. Pot experiments conducted with drought-tolerant cultivars Hanyou113 (HY113) Zhonghan3 (ZH3) drought-sensitive cultivar Huanghuazhan (HHZ) under four water management treatments (traditional flooding (CK), mild (LD), moderate (MD) severe (HD)) at heading stage in 2013 2014. Compared CK, yield was significantly reduced by 14.9%, 30.8%, 12.8% HY113, HHZ, ZH3 LD, 32.9%, 33.7%, 22.9% HHZ MD 53.6%, 45.6%, 30.7% HD, respectively. rate (Pn) decreased 49.0% from 20.0 10.2 µmol m−2 s−1 67.6% 23.4 7.58 39.3% 14.2 HD. Pn similar that CK conditions. During periods LD HD stage, potential (LWP) 31.9%, 54.8%, 15.7% ZH3, non-photochemical quenching (NPQ) flag leaves increased 150%, 97.6%, 218%, effective quantum PSII photochemistry (ΦPSII) 20.3%, 11.9%, 22.1% enzymatic activities superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) 11.4%, 18.0%, 21.8% 13.2%, 14.3%, 30.9% 13.4% 21.7%, 17.6% on average across two seasons. drought-resistant (HY113, ZH3) smaller than conventional (HHZ). Maintaining (LWP), Pn, photosystem II (PSII) original light energy conversion efficiency, non–photochemical coefficient (NPQ), increasing ratio photochemical reaction fluorescence antioxidant enzyme activity basis achieve a relatively high photosynthesis. These traits could be target breeder develop varieties.