Study On Biological Control Of Antagonistic Bacteria Against Rice Rhizocotonia.Sonali

Study on Biological Control of Antagonistic Bacteria against Rice Rhizocotonia. sonali Zheng Aiping Sichuan Agricultural University, Yaan 625014, Sichuan, China Abstract Some antagonistic strains were screened against Rhizocotonia.sonali AG-I in Sichuan. Five strains were selected according to the unorganized control and antagonistic test effects. The spraying concentration and time, colonization model were studied. On the base of the result, the field control test was conducted. Further the antagonism, promoting effect, physiological and biochemical characters were studied. The classification statuses in microbiology were deduced. The biological characters were studied for fermentation and application. Antagonistic mechanism was discussed in antagonistic protein and purified the protein for further cloning. 1. One hundred and fifty Bacterial strains isolated from healthy and infected rice plants, rhizosphere soils water in paddy field and sclerotia show antagonism to Rhizocotonia.sonali. Most of them inhibited mycelial growth of the pathogen in vitro. The inhibition zone wide of Tl22~ B34~ G22~. H50 were 1l.0~. l0.3~. 9.7~ 9.0mm respectively. 2. The test of unorganized control showed that H50~ G22 and B34 had the better control effects. Compared with water treatment, the control effects were 42.0%, 5 1.0%, 47.0% respectively. 3. The colonization of two antagonistic bacteria strains H50, B34 that showed antagonist to rice sheath blight on rice leaves in lab was studied respectively. It showed that after 20 days, the concentrations of the two strains were at low level, but the treatment of spraying the nutrient liquid after 13 days showed that the growth of strains rose to higher levels. The concentration test showed that the best control effects were connected with high concentrations. In studying on spray timing , the results indicated that the control effects were bad because of spraying too early or inoculating rice sheath blight too lately, and the appropriate timing to spray antagonistic bacteria is two day after inoculating rice sheath blight. iv ? 4. H50 G22. B34 bacterial strains isolated from the field showed strongly antagonistic effect on the sheath blight. The control effect against rice sheath blight AG-i and effect on rice yield were tested by seed and spraying treatments with the antagonistic bacteria. Triohoderma virde Jinggangmycin~ water were C.K. The results showed that in the soaking test, the control effect of B34 strain was the best one, 48.74%, and H50 strain showed the better promoting effect on tillering height and the number of the efficient seeds; while in the spraying test, the control effects of H50 three bacteria +jinggangmycin reached 60.75% and 67.96% respectively. The treatments of the mixed bacteria and H50 strain made the number of efficient seeds~ the weight of 1000 seeds ~the rate of seedling~ the length of spike increased respectively. 5. Inhibition rate, deformation effect, formation and germination effect of sclerotia of 5 strains, H50, B34, B25, G22and T122 with strong antagonistic effect were studied. By the antagonistic test to the Pyriczdaria grise...