Difference of physiological characteristics between Indica rice and Japonica rice in response to drought stress at booting stage

【Objective】This study systematically compared and analyzed the physiological characteristics of Indica rice and Japonica rice in response to drought stress at the booting stage, hoping to lay the foundation for the subsequent analysis of the physiological mechanism of the drought resistance difference between Indica rice and japonica rice.【Method】 Indica rice Zhenshan 97B(ZS97B) and Japonica rice Nipponbare(NP) with different drought tolerance capabilities were used as materials, normal watering and maintaining soil moist as control, stopped watering at booting stage, the stomata density and stomata opening degree, photosynthetic indexes, transpiration indexes and water physiological related indexes, antioxidant enzyme activity and malondialdehyde content were measured after 10 d of drought treatment. Rewatering after 13 d of drought treatment, the survival rate of rice after 10 d of rewatering was calculated statistically, comparison and analysis of the adaptability of ZS97B and NP to drought stress at the booting stage were conducted.【Result】After 10 d of stopping watering at the booting stage, the survival rate of ZS97B was 90.3%, which was extremely significantly higher than that of NP(77.8%) (P<0.01, the same below). The stomata density and stomata movement of two rice cultivars had no significant effect compared to the control(P>0.05), but the stomata density of ZS97B was significantly(P<0.05, the same below) or extremely significantly higher than that of NP before and after the treatment. Although the leaf rolling index of ZS97B was higher than NP, its photosynthetic rate was not severely affected. The photosynthetic rate of ZS97B decreased by 31.2%, while NP decreased by 62.9%. In addition, the leaf water loss rate of NP increased significantly under drought stress, and its leaf function damage was more serious than ZS97B. POD activity in leaves of ZS98B was extremely significantly increased to 32.46 U/(g·min) after drought stress, it was speculated that ZS97B responded more quickly to drought stress than NP;while the MDA content of NP also significantly increased to 1.55 μmol/g after drought stress, indicating that the damage of cell membrane was more severe than ZS97B.【Conclusion】Compared with the Japonica rice variety NP, the higher stomatal density of the Indica rice variety ZS97B alleviates the decrease in photosynthetic rate under drought stress at booting stage. At the same time, ZS97B reduces leaf transpiration rate by increasing leaf rolling index. In addition, the rapid response of ZS97B antioxidant enzyme system can also effectively eliminate active oxygen reduces cell membrane damage, and is more adaptable to drought stress at the booting stage.