Effects of hardening and plant age on development of resistance to cottony snow mold (Coprinus psychromorbidus) in winter wheat under controlled conditions

摘要

The development of resistance in winter-wheat seedlings to the cottony snow mold pathogen,Coprinus psychromorbidusRedhead et Traquair, was studied under controlled-environment conditions. Resistance was measured by the percentage of inoculated plants surviving after incubation at minus;3 deg;C for 8ndash;12 weeks. The number of weeks of prehardening growth prior to inoculation, fresh weight, LT50, and tiller number were positively correlated with resistance toC.psychromorbidus. Prehardening temperatures of 7 and 15 deg;C favored development of snow mold resistance compared with 2 deg;C, but the LT50(50 killing temperature) values of uninoculated plants were not significantly different. After 1 and 2.5 weeks growth at 20 deg;C, plants hardened at 2 deg;C and 12-h day length gradually increased in resistance to snow mold from 1 to 15 weeks of hardening. Development of resistance toC.psychromorbidusin winter wheat was most influenced by the amount of prehardening growth, and the development of freezing resistance played a minor role in disease resistance development. This form of resistance, which develops with increasing plant age, appeared to reduce the rate of infection and disease development byC.psychromorbidus.