| Rice bakanae disease caused by Fusarium moniliforme Sheld, was a systemic fungal infection diseases. The biological characteristics of Fusarium moniliforme, effect of sprouting and soaking temperature to disease rate were studied firstly and systematically in this paper. Evaluation standards was given and the resistance to rice bakanae of several cultivars was identified. The results were as follows:1. Biological Characteristics of Fusarium moniliformeFusarium moniliforme was isolated from seed and growth organic of sickness plant. The aerial mycelium was denseness, curled and white. Culture medium was purple. Vase-shaped peduncle was on aerial hypha. Minitype conidiophore was catenarian, unicellular, rotundity and the large conidiophore was falciform with 2-3 septums.The temperature range for hypha and sporulation was 5-35℃and the optimum one was 30℃. In the utilization of carbon source, the optimal source was disaccharides, and the most suitable nitrogen source was ammonium nitrogen. The range of pH value for hypha growth and sporulation was 4-12, and the optimum one was between 6-7. The fatal temperature of conidia and hypha was 58℃(10min) and 62℃(10min) respectively.2. Influence of different treatments to disease incidence6 different treatments were used to research the optimal infection condition. The results were indicated:(1) Soaking and pregermination were both influential to the disease and pregermination was more influential; (2) The most suitable soaking temperature to disease was 32℃-36℃; (3) The most suitable pregermination temperature to disease was 34℃-36℃; (4) The best germ length to disease infected was less than half of seed length; (5)The best inoculation amount was 106CFU/ml.3. Resistance identificationThe investigation results indicated that yield reduction was main due to tillering ability reduced, effective rice ear decreased,1000-seed weight and seed-setting rate lowered. Yield loss rate was consistent with disease rate. Correlation analysis indicated that disease rate in rice seeding field was significant correlative with yield loss rate, and the regression equation was y=1.024x-4.66. The equation suggested that disease rate was positive correlation with yield loss rate in rice seeding field.Through systematic investigation of 23 rice cultivars to bakanae disease in the rice seedling field and paddy field, the result indicated that the proper investigation periods for rice seeding field was 1-2 days before transplant seedlings and for paddy field was late tillering stage. Correlation analysis of disease indicence was carried out between seeding field and paddy field. The regression equation was y=0.0442+0.261x, and by F test it was highly significant correlation beween seeding field and paddy field. The result indicated that resistance to rice bakanae disease in seeding field was basically consistent with that inpaddy field. Through determining yield losses and systematic investigation, the evaluation standard of resistance was established. The resistance of 40 rice male sterile lines and 128 main cultivars was identificated. The results indicated that there was no high resistance resources in 40 rice male sterile lines, and 2 was R,9 was MR. But most of main cultivars were resitance, including 3 HR,94 R,22 MR,9 MS.4. Fungicides Screening in LaboratoryFive fungicides were tested in laboratory to determine the effect on the mycelical growth and germination of conidia. The results showed that carbendazim was the most effective one, thiophanate-methyl and mancozeb were two good fungicides, Chlorothalonil was inferior to mancozeb, and Mancozeb almost had no effect. |
PDF Full Text Request