【摘要】 采用γ射线诱发西瓜(Citrullus lanatus)染色体相互易位,获得了许多具有部分不育性的“复易位”(“多互换”)新品系。细胞学鉴定表明,这些品系的花粉母细胞在第Ⅰ次减数分裂中呈现出非常复杂的染色体结构。可分别表述如下:④+⑨Ⅱ(具有4条染色体组成的易位环+9个二价体);④+④+7Ⅱ;④+⑥+6Ⅱ;④+⑧+5Ⅱ;④+④+⑧+3Ⅱ;⑥+8Ⅱ;⑧+7Ⅱ;⑥+⑧+4Ⅱ;④+④+⑥+4Ⅱ;⑩+④+④+2Ⅱ;(12)+5Ⅱ以及“不联会”等等。此外在γ射线作用下还观察到多种异常的染色体分裂。例如染色体片断桥、落后染色体、染色体粘连及微核等。然而,这些变异对育种是无用的。从理论和实践方面来说,诱发的染色体易位越多,则杂合易位系的不育性越高。通过自交分离、选择和杂交育种,我们育成了几个少籽西瓜新品系,它们的结籽率较普通西瓜低50～80％,其极端类型单瓜仅有数粒种子。其中有些品系还具有高产、优质、早熟和耐贮藏的特性。更多还原

【Abstract】 Through chromosome reciprocal translocation induced by Y-rays many different multiple translocation strains with partial sterility were obtained. Cytologicalevaluation indicated that these strains possessed very complicated chromosome structure in the first reduction divisions of PMCs, they can be described as follows: ④ + 911 ( translocation ring with 4 chromosomes + 9 bivalent ) ,④ + ④ + 7Ⅱ, ④ + ⑥+6Ⅱ, ④ + ⑧ + 5Ⅱ, ④ + ④+⑧ + 3Ⅱ, ⑥ + 8Ⅱ, ⑧ + 7Ⅱ, ⑥ + ⑧ + 4Ⅱ, ④ + ④ + ⑥ + 4Ⅱ, ⑩ + ④ + ④ + 2Ⅱ,(?) + 5Ⅱ, and asynapsis, etc. In addition, different kinds of abnormal chromosome divisions were also observed, such as chromosome segments, bridges, Jagging chromosomes, chromosome adhesion, micro-nuclei, etc. But these variations are of no use for our breeding program. Theoretically and practically, the more the chromosome translocation was induced, the higher the sterility of translocation lines was. Through selfpollination, segregation, selection and cross oreeding, we developed several few-seed watermelon new strains, whose seed setting rate was 50-80% less than that of the common watermelons and the extreme type only has a few seeds, some of them with high yield, good quality, early maturity and long storage life.更多还原