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。 In this study, diploid selfing as the main control, tetraploid and diploid reciprocal cross-fertilization control, tetraploid watermelon self-fertility low embryo development. Through microscopic examination showed that: 1. Tetraploid watermelon selfing pollen germination rate is low, the pollen tube in the stigma and style growth abnormalities, slow growth in the style, 12h after pollination to reach the base of the style. 2. Tetraploid watermelon has a small number of abnormal embryo sac structure, but the share of less than 10%, not the main reason for low sex. 3. Tetraploid selfing double fertilization process is normal, but the number of embryos into the pollen tube less fertilization rate of only 35.8%. 4. Only a few embryos can self-fertilize in tetraploids and form viable embryos. Most of the embryos are aborted at the stage of embryos or globular embryos due to the abnormal disintegration of free nuclei or cellular endosperm. A few embryos differentiate into heart-shaped embryos and torpedoes After embryo, due to the premature dissolution of the endosperm cells, embryos stop the differentiation and abortion.