Physiological Mechanism of Drought-Resistant Rice Coping With Drought Stress

Benfu Wang,Xiaolong Yang,Liang Chen,Ping Li,Hongying Bu,Cougui Cao,Yang Jiang,Yuanyuan Jiang

doi:10.1007/s00344-021-10456-6

Abstract

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

Highlights

Rice (Oryza sativa L.), a staple food crop over the world, more than 65% of the population in China take it as their staple diet 1
To better understand the physiological mechanism of different genotypes cultivars coping with drought stress, we explored the changes of leaf water potential, chlorophyll content, photosynthesis, chlorophyll fluorescence, reactive oxygen species (ROS), yielding and their interrelationships using three different genotypes cultivars at at heading stage to analyze their responses to different level of drought stress
Except for carotenoids, the content of Chlorophyll a (Chla) and Chlorophyll b (Chlb) of flag leaves were significantly decreased under drought stress at heading stage and the chlorophyll content reduce along with the increasing of drought stress level

Summary

Introduction

Rice (Oryza sativa L.), a staple food crop over the world, more than 65% of the population in China take it as their staple diet 1. 95% of rice is produced under traditional puddled transplanted conditions, which leading to consumption of large amounts of fresh water. Previous studies suggest that rice production consumes about 65% of total agricultural water consumption 2. With the global climate change, the uneven spatial-temporal distribution of precipitation has caused a severe shortage of freshwater resources, and seasonal drought stress has become a crucial abiotic factor restricting the development of traditional puddled transplanted rice production system in Central China 3-5. The sensitivity to water deficit shows significant difference at different growth period of rice, many previous studies have shown that reproductive stage is the most susceptible period for rice leaves were significantly reduced under drought stress at heading stage, which resulted in a conspicuous decrease in dry matter accumulation. The proportion of dry matter allocated to grains increased, it was not enough to prevent the yield declining 10-

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Discussion

Conclusion