不同碳氮比对棉花黄萎病菌主要生物学性状及致病力的影响

【目的】 研究不同碳氮比(C/N)营养条件对棉花大丽轮枝菌(Verticillium dahliae Kleb.)主要生物学性状及致病力的影响。为调整碳氮比例减少大丽轮枝菌的为害提供理论依据。【方法】 将不同致病类型的2个大丽轮枝菌菌株在不同碳氮比的培养基上进行培养,测定大丽轮枝菌的微菌核形成、产孢量、菌丝量、孢子萌发率及致病力。【结果】 不同碳氮比营养条件明显影响大丽轮枝菌落叶型菌株微菌核的形成,在低碳氮比(25∶1～30∶1)中形成的微菌核明显多于在高碳氮比(45∶1～50∶1)中形成的微菌核。25∶1的碳氮比最有利于大丽轮枝菌产孢和菌丝生长,碳氮比高于35∶1大丽轮枝菌产孢量和菌丝生长量明显减少。40∶1的碳氮比最有利于大丽轮枝菌的孢子萌发。在感病品种上,25∶1的碳氮比最有利于大丽轮枝菌致病,碳氮比高于35∶1大丽轮枝菌致病力明显减弱;只有35∶1的碳氮比才有利于大丽轮枝菌致病,过高或过低的碳氮比都不利于大丽轮枝菌致病。【结论】 不同碳氮比营养条件对两种不同致病类型大丽轮枝菌的生长、繁殖及致病力都有影响,低碳氮比(25∶1)有利于大丽轮枝菌的菌核形成、分生孢子产生和菌丝生长,在感病品种上表现出较强致病性;高碳氮比(高于40∶1)不利于大丽轮枝菌生长、繁殖和致病。

Effects of Different C/N Ratio on the Main Biological Characteristics and Pathogenicity of Verticillium dahliae in Cotton

【Objective】 To explore the influence of different carbon to nitrogen (C/N) ratios on the biological characteristics and pathogenicity of Verticillium dahliae Kleb.【Method】 Two strains of V. dahliae with different pathogenic types were cultured in six media with different C/N ratios, the biological characteristics of V. dahliae including microsclerotial formation, conidial production, mycelial yield and conidial germination rate were measured, and the virulence of V. dahliae to cotton were evaluated.【Result】 The results of cultural characteristics showed that the microsclerotial formation of the defoliating type virulent V. dahliae strain was significantly affected by different C/N ratios. The microsclerotial produced more at the C/N ratio of 25∶1-30∶1 than at the C/N ratio of 45∶1-50∶1. The C/N ratio of 25∶1 was the most favorable for conidial production and mycelial yield of V. dahliae, while conidial production and mycelial yield were significantly reduced when C/N ratio was higher than 35∶1. Optimal C/N ratio for conidial germination of V. dahliae was 40∶1. The results of pathogenicity assays indicated that C/N ratio of 25∶1 was the most favorable for causing disease in the susceptible cotton variety, V. dahliae displayed significantly reduced disease severity when C/N ratio was higher than 35∶1; whereas C/N ratio of 35∶1 was optimal C/N ratio for causing disease in the resistant cotton variety, V. dahliae reduced significantly disease severity when C/N ratio was lower or higher than 35∶1.【Conclusion】 Different C/N ratios have different influence on growth and pathogenicity of V. dahliae, the C/N ratio of 25∶1 is not only conducive to the microsclerotial formation, conidial production and mycelial growth, but also conducive to the pathogenicity of V. dahliae in susceptible variety; C/N ratios higher than 40∶1 are not beneficial to the growth, reproduction and pathogenicity of V. dahliae. The results will provide a theoretical basis for us to study disease control strategies by adjusting C/N ratio.