航天诱变向日葵SP_7植株中顶芽突变系的跟踪观察

Successive Observation on Mutant Plants with Abnormal Buds in SP_7 Generation of Sunflower Induced by Space Flight

对经航天诱变向日葵种子的第7代植株进行性状考察,发现来自第6代单株套袋的42株幼苗中有12株第1对真叶表现出明显延长.对这12株进行形态跟踪观察,发现其中仅1株顶芽发育正常;其余11株的顶芽则出现了不同的差异,8株顶芽未发育,2株顶芽仅发育出1片叶片,1株顶芽先瘤化,再长出叶片,最后分化出新芽.虽然变异植株的顶芽的发育具有不定向性,但是随着时间的延长,突变株第1对真叶与子叶之间的部位生长出2个侧芽,这些芽能够正常的发育成独立的茎秆并结实,有很强的增产潜力,为寻找高产向日葵的育种工作者提供好材料.通过观察还发现,所有的突变体的第1对真叶都比正常植株有很明显的延长,在种苗期就可以很容易地把能够发育成2个或3个茎秆的植株筛选出来.

When investigating the morphylogical characters of the seventh generation（ SP7 ）plants of sunflower （He- lianthus annuus L. ）, whose original seeds were treated by space /light, 12 plants in 42 plants from a single SP6 plant by inbreeding were found with obvious elongation of the first pair of true leaves. Results of successive observation showed that, in these plants, only one developed with normal apical bud, while the apical buds of other 11 plants varied in development： 8 without developed apical buds; 2 with one true leaf from apical buds; 1 with nor- mal true leaves from tuberculate bud, then to normal shoot. Although, there is not directional development on ter- minal bud of the mutation plants. However, with further development, two axillary buds were differentiated from the postion between the cotyledon and the first pair of ture leaves, and grew to two or three independent stems and fruits afterwards. By comparison, it was found that the seed weight of single plant with two or three stems in a sin- gle plant was higher than that of palnt with single stem, providing a good high - yielding sunflower material for breeding. Fortunatlly, the two or three shoot buds mutant plants with significantly enlongated true leaf in seedlings were readily screened out.