Studies On The Biological Characteristics Of Different Pathotypes Of Phytophthora Sojae

The Soybean bilght,also called Phytophthora root rot of soybean,is caused by Phytophthora. It is one of the most serious diseases on soybean production.It’s destructive and can significantly inhibit the production of soybean.It can give rise to loss billions of dollars a year. Once passed, the disease can live in the endemic area for a long time and it’s difficult to deracinate. Because of Soybean phytophthora will damage the quality of soybean and reduce production,we must select disease-resistant varieties and combined with comprehensive control. However, the Soybean phytophthora has obvious phenomenon of physiological differentiation and many physiological races,the resistance of disease-resistant variety will quickly overcomed by ney physiological races of Soybean phytophthora.So it takes hard difficulties to breeding for disease resistance. Biological characteristic of 5 different pathotypes isolates of Phytophthora sojae were researched and compared, The results showed:1. The mature sporangia, which are not of uniform size, were inverted-pear-shaped, and were 32.5 to 115.0μm in length, and 25.0 to 67.5μm in width. Oogonia were pale yellow, spherical shapes, and were 23.75 to 46.25μm in diameter. Antheridium were paragynous, and were 7.84 (3.50-15.00)μm in length, and 9.11 (5.00～20.00)μm in width.2. On the LBA media, growth rate of the tested isolate GZ6 was the fastest, with the average rate of 4.7mm/d,then was the 6497,14,12and17,the growth rate of them were 4.6mm/d,4.5mm/d,4.4mm/d and 3.8mm/d. On the OM media, growth rate of the tested isolate 12 was the fastest, with the average rate of 17.6mm/d,then was the 6497,17,GZ6 and 14,the growth rate of them were 17.3mm/d,17.2mm/d,16.6mm/d and 15.8mm/d.3. Pathogenicity of different pathotypes of Phytophthora sojae to soybean was studied. The results showed that in the Hefeng 35,the pathogenicity of the tested isolate 12 was the highest, followed by 6497,14,GZ6 and 17, and in the Henfeng 47, the pathogenicity of the tested isolate GZ6 was the highest, followed by 12,6497,17and 14.The results of variance analysis indicated that the pathogenicity of different pathotypes of Phytophthora sojae to soybean have highly significant difference.