关键词: 华北落叶松, 华北落叶松, 人工林, 间伐, 林下植被, 物种多样性

Abstract: In three different precipitation years from 2003 to 2006, the yield and agronomic characteristics of 28 wheat varieties under only one winter irrigation were compared with those under normal four irrigations. The results are: (1) The tested wheat varieties had significantly different resistance to drought according to the yield level. Under only one winter irrigation, there was a close relationship between yield level and growth-period precipitation. (2) “Jingnong 02-2”, “Zhongmai 326”, “Beinong 9580”, “Zhongmai 12”, “Jingnong 04-133” and “Jingdong 8” had a better drought resistance among the tested varieties, with “Zhongmai 326” showing a better adaptation to water stress in heavy and normal precipitation years. (3) Under dry soil conditions, the formation of wheat spike from the tillers was influenced most, which could be used as the early appraisal and screening index for wheat drought resistance. (4) The varieties with better drought resistance can be widely used for water-saving cultivation techniques in heavy and normal precipitation years to relieve water resource deficiency of this district. However, only one irrigation in winter cannot meet the need of the normal wheat growth in drought years, and wheat yield decreased more than 48.89% compared to the normal irrigated wheat varieties in the drought year.