渭北旱塬地区油菜种植面积占全省40%左右,亩产长期徘徊在几十斤的水平,一个突出原因是收获时严重缺苗,亩收获株数通常不到万株。造成缺苗的因素较为复杂,如干旱、冻害等自然灾害,以及病虫、耕作栽培等,除特殊年份外,干旱一般不致造成直接死苗,而是加剧冻害和病虫害的严重程度。根据研究,适期播种是控制油菜毒素病,培育适龄壮苗,防止油菜越冬死苗的有效措施。但是,旱塬地区播种期受降水早晚的制约,生产中偏早播种,是当前的主要偏向。早播不仅是油菜毒素病发生的重要条件,也是造成菜苗冬旺早衰,引起越冬死苗的重要因素。近几年来,在研究旱地油菜越冬保苗技 The planting area of ​​rapeseed in Weibei arid highland area accounts for about 40% of the province, and the long-term hibernation of mu production is at the level of several ten catties. One of the prominent reasons is that there is a serious shortage of seedlings at harvest, and the number of harvested harvesters is usually less than 10,000. The factors causing the lack of seedlings are more complicated. Natural disasters such as drought and frost damage, as well as pests, diseases and tillage and cultivation, except for special years, usually result in direct death of young seedlings instead of dead seedlings, but aggravating the severity of frost damage and pests. According to the study, sowing is the proper control of rape toxin disease, age-appropriate seedlings to prevent over-wintering seedling effective measures. However, the sowing period in the dry-land areas is limited by the precipitation in the morning and evening, and the earlier sowing in production is the main current bias. Early sowing is not only an important condition for the occurrence of canola toxin disease, but also an important factor that causes the winter wheat seedlings premature aging, causing overwintering dead seedlings. In recent years, dry rapeseed in the study of seedling protection techniques