棉花种间杂种后代育性的研究

棉花种间杂种:G.hirsutum(2n=52)×G.thurbeti(2n=26),F_1的染色体数2n(3x)=39,属于三倍体,因而杂种植株高度不育。从花粉粒形态鉴定,大都是不规则形,其中正常园形的约占14％,但花药又不破裂。用染色剂测定其花粉生活力,不着色者占89％,浅红色者占11％,均为失活花粉。观察杂种F_1(3x)的花粉母细胞,在减数分裂时,染色体大都不配对,单价体数20个左右。而且分裂未期多数P.M.C形成具有5—12个的多分孢子体。这都表明雄性配子败育,导致杂种植株表现为高度不育。用秋水仙碱和DMSO等药物处理杂种枝条,获得染色体加倍的嫁接植株,镜检花粉母细胞,减数分裂的中期相,其二价染色体数为25—32对。分裂末期,形成正常四分体数占95％以上,花粉生活力也显著的提高,因此杂种株的育性得到一定的恢复。同时随着回交世代的延续,杂种育性逐渐提高。利用棉花种间杂种后代的多样性,从中选出抗病、抗虫高纤维强度等新类型,已供棉花育种应用。

FERTILITY STUDIES OF INTERSPECIFIC HYBRID COTTON

Cotton interspecific hybrid G. hirsutum 2n(4x)=52 and G. thurberi 2n(2x)=26 is a triploid 2n(3x)=39 with high sterility. Most of their pollen granules, without dehiscence, shaped abnormally and had no vitality. According to the dye test, few of chromosome Parting at meiosis leading to polyspory (each PMC produced 5—12)dung telophase,so obtained a lot of hybrid plants with male-steril pollen By soaking the twigs in colchicine solution, grafted plants with double set of chromosomes were obtained. According to the mcroscope examinations, at meiosis of PMC among these formal tetrads were more than 95 percent. the pollen vitality of these plants was significantly increased with the back crossing generation increasing, the hybyid fertility was partially restored, the selection of disease-resistant, insect-resistant, and favourable fiber character was carried out among the various progenies.