新疆不同抗寒性小麦品种越冬过程中受冻时期的细胞学观察

越冬冻害是新疆冬小麦生产中很严重的自然灾害,严重时死苗面积达20％以上。因此,防止越冬冻害是发展新疆冬小麦生产的关键问题。而对冬小麦越冬冻害的原因一直存在不同的看法:一是,冻害是由于冬季严寒,由最低温度造成。另一是,越冬过程中天气发生暂时性转暖,尔后又遇寒流,使麦田发生冻融交替。以致在寒流再度到来时,虽未超过该品种能忍受的低温极限,也会发生严重冻害。在某些地区和某些年份可能是主要的因素。第三种是以上两种看法的综合。为此,查明越冬冻害时期,对冻害原因的判断具有重要作用。因此,我们试图通过对新疆冬小麦越冬过程中的细胞学观察,探讨越冬中的冻害问题,为防御冻害提供依据。

Cytological Studies on the Freezing Period of Winter Wheat During the Winter in Xinjiang

The cyto-morphological changes of three wheat varieties with different resistance to coldness in the overwintering period have been observed. By means of the indicator of nuclear structure changes, it is indicated that the nuclear structure in the seedings of varicty Xindong No.1 in the overwintering period maintained their normal morphology and did not produce damaging change (Figs.1-3). A few of nucli in tillering and young leaf cells of variety Xindong No. 2 showed injured phenomenon by the middle January and February, and disruption of most of nucli in tillering tissue of some specimens occurred when early and mid March (Figs. 4-6). These results indicated that some seedlings of variety Xindong No.2 began to be subjected to freezing injury in mid winter and died in early spring. The nucli in seedlings of less cold hardy variety Keshibaipi were severely disrupted in mid January (Figs. 7-8), showing they died in low temperature of the mid winter. During the temperature fell into the mid winter, the different morphological changes of the nucleoli in 3 wheat varieties (Figs. 1-3, 4-6, 7-8) showed the growth of seedlings of weaker cold hardy varieties Xindong No. 2 and Keshibaipi stopped later than strong hardy variety Xindong No. 1. The result provided important information for studing the mechanism and way on the development of plant hardiness and way on the development of plant hardiness.