南丰蜜橘无核成因的研究

Causes of Seedless Forming of Nanfeng Tangerine

观察和分析南丰蜜橘[Citrus reticulata Blanco var.kinokuni(Tanaka)H.H.Hu]的花粉育性、成熟胚囊结构以及胚胎发育情况,探讨其产生无核现象的原因。结果表明:南丰蜜橘的花粉具有一定的生活力和萌发率,属于中育性花粉;南丰蜜橘胚囊发育正常;授粉4周后大部分合子胚发育停滞并且出现败育迹象;饱满种子在授粉8周后胚发育到心形胚阶段时,部分种子的胚乳开始瓦解,到授粉16周后退化形成瘪籽和痕迹,另一部分发育成正常种子和充满胚乳的饱满种子;到成熟期时,小果系、早熟系南丰蜜橘种子全部退化,大果系南丰蜜橘种子大部退化,形成无核果实。胚胎早期败育是南丰蜜橘无核的主要原因。

Nanfeng tangerine [Citrus reticulata Blanco vat. Kinokuni （Tanaka）H. H. Hu] was used for studying its seedless forming causes based on the observation of pollen fertility, embryo sac development, and embryonic development. The results showed that the pollen fertility of Nanfeng tangerine belongs to the medium fertility pattern. The mature embryo sac of the Nanfeng tangerine was normal. Most of zygotic embryo stopped growing and began to abortion at 4 weeks after pollination. Some plump seed endosperm began to collapse when the embryo developped into heart-shaped embryo at 8 weeks after pollination, and formed empty-seed and degenerated seeds with funiculi could be observed until 16 weeks after pollination. Another plump seeds developed into normal seeds or plump seeds which filled with endosperm but abnormal embryo. All seeds of Xiaoguo Nanfeng and Zaoshu Nanfeng and most seeds of Daguo Nanfeng were degradated in mature fruit. It is hence proved that embryo degeneration is responsible for the seedless of Nanfeng tangerine.