Resistance evaluation of soybean varieties to phytophthora root rot in South China

Objective To systematically evaluate the resistance levels of soybean varieties to 7 strains of Phytophthora sojae in South China.

Method Sixty seven soybean extension cultivars and main parents were identified for the resistance to 7 strains of Phytophthora sojae using the hypocotyls inoculation technique.

Result and conclusion The infection rates of PGD1, Pm14, Pm28, PNJ1, PNJ3, PNJ4 and P6497 were 86.6%, 80.6%, 85.1%, 61.2%, 77.6%, 74.6% and 80.6% respectively, while 9.0% of the cultivars or lines were resistant to PGD1 strain which was newly found and isolated in Guangdong Province. Soybean varieties resistant to the Phytophthora strain PGD1 included Huaxia6, Yuexia2011-4, Guichun6, Guichun10, Guixia1 and Zhechun3. Among all tested species, twenty nine cultivars were susceptible to the 7 strains (accounting for about 43.3%). There are few Phytophthora-re- sistant soybean varieties in South China. It is necessary to breed and extend resistant cultivars(lines).