Abstract:

Rice blast is one of the most serious diseases in organic rice production. To clarify the effect of several biological agents on controlling rice blast and improving yield and quality of organic rice, the disease severity, defense enzyme activities, and yield and quality indexes were detected after seed treatment and foliage spraying using the biological agents. Results showed that the biological agents used for seed soaking combined with foliage spraying had high control effects on rice blast, and the control effect of Bacillus subtilis, shenqinmycin and kasugamycin on leaf-blast was 62.84%, 58.11% and 54.05% respectively, and the disease index control efficacy was 81.07%, 56.49% and 46.11% respectively, the control effect on panicle-blast was relatively poor, 63.63%, 54.62% and 54.05% respectively, and the disease index control efficacy was 48.92%, 34.23% and 29.85%, respectively. After treatment with biological agents, the activities of defensive enzymes in rice plants were significantly increased, and most of them reached the maximum within 1-7 days. Yield-related indexes such as grain number per panicle, seed setting rate and 1000-grain weight increased significantly while the rate of brown rice, milled rice and head milled rice increased slightly. The content of amylose and protein increased slightly while the rate of chalky and green rice decreased significantly. The results indicated that application of biological agents could effectively control rice blast and improve the yield and quality of organic rice.

Key words: yield, quality, control effect, rice blast, organic rice