Study on Relation of Mycelial Growth and Spore Germination of Alternaria alternate Caused Occurrence of Citrus Brown Spot

Biological characteristics of Alternaria alternate, which caused occurrence of Citrus Brown Spot, were studied. The results indicated that five carbon sources could be used, but the conditions between mycelium growth and spore germination were different. The most suitable carbon source for mycelium growth and spore germination was mannitol, and sucrose was not suitable carbon source for mycelium growth and maltose was not suitable for spore germination. Although all of five nitrogen sources could be utilized by strain growth, the conditions between mycelium growth and spore germination were various. The most suitable nitrogen source for mycelium growth and spore germination was glycin. In the nitrogen sources trial, it revealed that ammonium nitrate was the worst for mycelium growth and ammonium sulfate was the worst for spore germination. Temperature and pH had effects on the mycelium growth and spore germination, the suitable temperature for mycelium growth and spore germination was 21 ℃, it could grow well under the pH value of 5～8. The results also indicated that the treatment with different light conditions did not significantly affect the mycelium growth and spore germination.