The Screening Of Nitrate-nonutilizing(Nit) Mutants Of Maize Curvularia Spp.and Its Vegetative Compatibility

20 strains of Curvularia spp. leaf spot were isolated from Maize and Rice in different areas of Sichuan,Sandong and Henan. The effects of different conditions on Nit mutants' formation were studied. Nit mutants stability was tested, and their phenotypic classes were identified. In addition, vegetative compatibility of the tester strains was analyzed. They showed that:Wild isolates growth ability was very important for Nit mutants to form, and the optimum activity time was 3-5d; PDC media wasn' t suitable to induce Curvularia spp. to produce Nit mutants, but KPS media can be used to induce Nit mutants from most of tested strains; the optimum KClO3 concentration was 1.5-2.5%, and in this range different strains demanded different proper concentration of KC1O3; 25 compared with 29 , the former was more fitting; the irradiation wasn' t in evident relation to Nit mutants' induction.1848 Nit mutants from 20 tester strains were designated, it showed that: Nit mutants from Curvularia spp. were highly stable, and percentages of stable mutants were 74.4-91.7%.All Nit mutants obtained were identified depending on their ability of using nitrogen source, which found that: the appearance frequencies of Nitl and NitM mutant classes at 25-95.9% and 1.2-9.5%, respectively. 33-4 , Santai, DanW-4, Rye-1 , R2-5 and R3-2 Strains didn' t produce NitM mutants.Vegetative compatibility were tested of Curvularia spp. according to thecomplement between Nitl and NitM mutants, it showed that: the other tester strains were self-compatibile, except 33-4, Santai, DanW-4, Rye-1, R2-5 and R3-2 isolates; vegetative compatibility tests among all strains showed that: 33-4, C4, C7 and R2-5 strains belonged to VCG1, and the other 14 strains were pertain to VCG2, but Rye-1 and R3-2 strains didn' t belonged to both VCGiand VCG2.Basis the pairing among all wild strains on PDA, the tester strains were divided into other two vegetative compatibility groups(VCGi' and VCG2' ). 33-4, Rye-1 and R3-2 strains belonged to VCG1' , the other tested isolates belonged to VCG2' . The result of two kinds of test were different. But they both showed that: the population of Curvularia spp. from Maize in Sichuan Province had diversity.