Effect Of Brassinolide On Rice Germination And Growth

Brassinosteroids(BRs)are a class of phytohormones with high physiological activity at very low level of dosage.BRs play important role in plant growth and development,such as the promotion of photosynthesis,germination increase of seeds,the aging inhibition of plant organs and stress resistance.Among BRs,brassinolide(BL)shows highest physiological activity and its physiological function indicates great utilization potential in agricultural production.Rice(Oryza sativa L.)is of critical importance to food security and the increases of rice yield and economic performance are of great significance.In this study,Zhuliangyou 819 was used as the experimental material to systematically analyze the effects of BL on rice seed germination,seedling growth,plant resistance and yield.The results were as follows:(1)BL can increase the germination rate of seeds,and promote the rapid and uniform germination of rice seeds.The germination rate of the control was about 61%.Under treatment of distilled water soaking + BL sprouting,the germination rate was about 71.5%.The germination rate of BL soaking + distilled water sprouting treatment was about 80% with significant difference(P<0.01).Comparing the two different treatments,the final germination rate was also significantly different(P<0.05).The results indicated utilization of BL soaking + distilled water sprouting was beneficial to seed germination.(2)BL soaking can significantly relieve the inhibition of ABA in seed germination.The root length of rice seeds treated with 50 mg/L ABA+100 μg/L BL was about 2.5 mm longer than the root length of 50 mg/L ABA-treated group.Meanwhile,ABA + BL treatment of rice seed germination rate was up to 98.5% and significantly higher than that of ABA treatment.(3)BL promotes the homogenous growth of rice seedlings.BL has a significant effect on the embryo growth,as it was found that distilled water soaking + BL sprouting inhibited the growth of embryo,while BL sprouting + distilled water soaking promoted embryo germination growth significantly.In addition,when the 7-day old rice seedlings were sprayed with 100 μg/L BL and water respectively,the plant height,root length and biomass of seedlings were significantly increased with BL treatment.The height and dry weight of seedlings with BL treatment were significant different than that of the control.In the meantime,the root activity was also significantly increased.(4)Spraying BL significantly enhanced rice stress resistance characteristics.After BL sprayed,the peroxidase activity of rice was induced by 21.1% than that of the control,the catalase activity was induced by 38.5%,and the activity of superoxide dismutase was induced by 12.0%.(5)BL treatment can increase rice yield.When 100 μg/L BL was sprayed at the heading stage,the number of saturated grains per ear increased by 23%,and the yield increased by 22%.