1973 Volume 8 Issue 2 Pages 53-63
Hatching and development of larvae of the soybean cyst nematode, Heterodera glycines ICHINOHE, was compared between eggs deposited in the gelatinous matrix and those inside cysts of pale-yellow colour stage and brown stage under different conditions. A larger number of gelatinous matrix as well as eggs in it was produced when the host plants were given full nutrients under long-day treatment than hosts grown without fertilizer or under short-day treatment with full nutrients. It is considered that retardation of plant growth due to the lack of fertilizers or early initiation of flower bud formation caused by short photoperiod resulted in the early maturation of nematodes and a smaller number of eggs deposited in the gelatinous matrix. Larvae from gelatinous matrix and pale-yellow cyst entered the host roots earlier than those from brown cyst. Brown cyst was more resistant than the gelatinous matrix or pale-yellow cysts to the treatment with a 1 : 1, 000 dilution of EDB emulsifiable concentrate for 10 min, which was evaluated by the larval invasion of host plant roots. Experiments in which eggs of the gelatinous matrix or cyst in moist sand (moisture : ca. 20%) were subjected to various temperatures including the lowest temperature of -10°C for different periods (max. 90 days) showed the delay of hatching in distilled water at 25°C. The larval invasion of host roots was more decreased after the above treatments by those from gelatinous matrices and pale-yellow cysts than those from brown cysts.
