Effect of inoculation temperature and soybean genotype on root penetration and establishment of Heterodera glycines

Abstract

In order to study the effect of resistance and temperature on soybean cyst nematode development, soybean cultivars Bell (PI88788 resistance) and S20-20 (susceptible) were inoculated by transplanting into H. glycines infested soil maintained at 20, 25, 30 or 358C. After 10 days, seedlings were either transferred to hydroponic culture to study male development or transplanted into sand to study female development. The mean number of males on S20-20 (2524/g of dry root) did not differ significantly from the mean number on Bell (2418/g of dry root). Numbers of males and females were highest on seedlings incubated at 308C during inoculation. The average length of males on Bell (1065 mm) was slightly but not significantly less than males on S20-20 (1126 mm). Short, abnormal males, < 800 mm in length, with spicules and stylets were observed in populations from Bell. The mean number of females was significantly higher on S20-20 (818/g of dry root) than on Bell (216/g of dry root) regardless of inoculation temperature. The mean number of eggs per female was significantly higher on S20-20 (253/cyst) than on Bell (60/cyst). The male to female ratio was highest at 358C.