四倍体西瓜低稔性胚胎发育研究

试验以二倍体自交为主要对照，四倍体与二倍体正反交为辅助对照，研究了四倍体西瓜自交低稔性的胚胎发育。通过镜检观察表明：1．四倍体西瓜自交花粉萌发率低，花粉管在柱头与花柱中生长出现异常现象，在花柱中生长缓慢，授粉后12h到达花柱基部。2．四倍体西瓜有少数结构不正常胚囊，但所占比率低于10％，不是稔性低的主要原因。3．四倍体自交双受精过程正常，但花粉管进入的胚囊数少，受精率仅35．8％。4．四倍体自交只有少数胚能正常发育，形成有活力种胚；大部分胚由于游离核或细胞化胚乳的异常解体，在原胚或球形胚阶段败育；少数胚分化到心形胚、鱼雷胚后，由于细胞化胚乳过早解体，胚停止分化而败育。

Study on the Embryonic Development of Low Fertility Tetraploid Watermelon

The embryonic development of the low fertility autotetraploid watermelon(4x × 4x), 2x× 2x, 4x × 2x and 2x × 4x watermelons were studied. Results showed: 1. the percentage of pollen germination and the growth rate of pollen tubes in the styles of the self-pollinated tetraploid(4x×4x) were the lowest, and there often appeared the abnormalities of pollen tubes in the stigmas and styles; 2. before fertilization a few abnormal embryo-sacs were also found(less than 10% ) ; 3. the process of fertilization in 4x× 4x was normal (which occured only a little later), but the number of embryo-sacs to which the pollen tubes reached was the least when compared with those of three controls, and leading to low frequence of double fertilization (only 35.8); 4. In 4x × 4x, most of embryos aborted at different developmental stages, and only a few embryos arrived mature and alive. In the aborted embryos, most embryos degenerated at globular stage due to abnormal degeneration of free nuclei or celluar endersperm, and a few stopped differentiation and degenerated at heart or torpedo stage due to early degeneration of cellular endosperm.