The Effect Of Drought Stress On Rice Leaf’s Photosynthesis, Rice Grain Yield And Rice Quality

This study is carried out at nethouse of Hua Zhong Agriculture University in city of Wu Han, Hu Bei Province of China in 2014, set three different drought resistance rice varieties, Zhonghan3 hao,Hanyou113 and Huanghuazhan, as the object. The experiment is setted 4 treatments level, Check(CK), low drought(LD), moderate drought(MD) and high drought(HD), in booting and heading stage, and conducted to study the effect of drought stress on rice leaf’s photosynthesis, rice grain yield and rice quality. The main results are summarized follows:1. Although LD treatment and CK have no significant difference on rice leaf’s photosynthesis and antioxidant enzyme, MD or HD made leaf’s Pn fall by 12.9% ~ 43.9% that’s related to Gs mainly, made activity of antioxidant enzyme rise, and made sensitive variety Huanghuazhan leaf’s MDA content increase. As well as, the drought resistance varieties showed more stability than sensitive variety in photosynthesis and antioxidant enzyme. After re-watering from drought treatment to filling stage, photosynthesis and antioxidant enzyme could return to normal status under different treatment in booting stage. But there was one point gap between HD treatment and CK instead of LD and MD treatment in sensitive variety Huanghuazhan leaf’s Pn, Gs and activity of antioxidant enzymes that meant these damage were not recovered, instead of the valve of SPAD and MDA. What’s more, all treatments returned to CK’s level on all indicator of three rice varieties leaf’s photosynthesis and antioxidant enzyme in heading stage.2. Drought stress made grain yield fall by 14.3% ~ 47.9% in booting stage, and the more serious the drought degree was, the greater the grain yield decreased because of reducing significantly of panicles and grain filling mainly, as well as grain filling of first branch and number of branch per panicle of secondary branch. Moreover, Drought stress made grain yield fall by 11.0% ~ 34.1% in heading stage, and the more serious the drought degree was, the greater the grain yield decreased because of reducing significantly of grain filling mainly, and grain filling of first branch, but number of branch per panicle of secondary branch had no significant loss. From the correlation analysis, grain yield and leaf’s Pn had no significantly correlation in booting stage, but grain yield was positively related to leaf’s Pn significantly(p<0.05), positively Gs and valve of SPAD high significantly(p<0.01) and negatively the activity of SOD high significantly(p<0.01). Drought stress reduced significantly dry matter in maturity stage and harvest index in booting and heading stage. Drought promoted sensitive variety Huanghuazhan’s translation and contribution rate of dry matter and stem NSC after flowering in booting stage. Two varieties’ translation and contribution rate of dry matter and stem NSC after flowering were increased under different drought treatment in heading stage. But it didn’t make up loss of yield because of decrease of grain filling.3. In booting stage, treatments could increased significantly Zhonghan3 hao grain’s milled rice ratio by 2.7% ~ 3.3% that means processing quality’s improvement, instead of HD treatment. To Huanghuazhan, drought had no significant difference on grain’s processing quality. Drought resistance variety Zhonghan3hao’s chalky rice rate and chalkiness were decreased significantly by 21.7% ~ 40.4% and 45.3% ~ 58.6% respectively under MD and HD treatment that maybe because of the continuous wet weather that meant Zhonghan3 hao leaf not suffered from drought stress. But to Huanghuazhan, LD treatment made chalky rice rate and chalkiness reduce significantly, and MD and HD treatment increase that show that make exterior quality inferior. In heading stage, treatments could increased significantly Zhonghan3 hao grain’s milled rice ratio by 1.9%, instead of HD treatment. And Huanghuazhan’s milled rice ratio had no significant difference between treatments. Two varieties grain’s head rice ratio were increased significantly by 3.8% ~ 4.1% under HD treatment. And two varieties’ exterior quality had no significant difference between treatments. What’s more, two varieties’ protein content and amylase content had no significant difference between treatments in booting and heading stage.