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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。
Using the γ-ray to induce reciprocal translocation of chromosomes of Citrullus lanatus, a number of new “metathesis” new lines with partial sterility were obtained. Cytological identification showed that the pollen mother cells of these lines showed a very complex chromosomal structure at the first meiosis. Can be expressed as follows: ④ + ⑨ Ⅱ (with 4 chromosomes composed of translocation ring +9 divalent); ④ + ④ +7 Ⅱ; ④ + ⑥ +6 Ⅱ; ④ + ⑧ +5 Ⅱ; ④ + ④ + ⑧ + 3 Ⅱ; ⑥ +8 Ⅱ; ⑧ +7 Ⅱ; ⑥ + ⑧ +4 Ⅱ; ④ + ④ + ⑥ +4 Ⅱ; ⑩ + ④ + ④ +2 Ⅱ; (12) +5 Ⅱ and “not the Union” and so on. In addition, a variety of aberrant chromosomes were also observed under the action of gamma rays. Such as broken chromosome bridge, backward chromosomes, chromosome adhesion and micronuclei. However, these variations are useless for breeding. In theory and practice, the more chromosomal translocations are induced, the higher the sterility of the heterozygous translocations. By self-isolation, selection and cross breeding, we have developed several new lines of young watermelon seedlings that have a seed setting rate of 50-80% lower than common watermelons and only a few seeds in the extreme type. Some of these lines also have high-yield, high-quality, precocious and storage-resistant properties.