Studies On Mechanism Of Few-seeds In Watermelon Germplasm-F₀₁₁

Watermelon is one of important horticultural crops, which have high economic value.Seedless and few-seed watermelon with high quality, convenient eating, disease resistance and long storage, welcomed by consumers. Seedless or few-seed watermelon can be achieved through a variety of ways. In addition to triploid seedless watermelon, there were many other ways to get seedless or few-seed watermelon, such as using soft X-ray irradiated pollen produce diploid seedless fruit, using exogenous hormone induce parthenocarpy watermelon, chromosome translocation, using modern transgenic technology, and so on.However, the current main method of production seedless watermelon, so-called the triploid seedless watermelon, exists some problems, for example: the seed was too expensive, low of germination rate and seedling emergence rate. Therefore, make clear of seed sterility mechanism and causes, thereby creating high-quality few-seed watermelon germplasm, and developing seedless watermelon varieties on diploid level, the application prospects will be promising.The watermelon germplasm F011 and F1 was first researched systematically in cytology and physiology. The results were as follows:1. In mid-May, at about 8:30-8:50, 1.2-1.8mm male flower buds were picked; directly fixed in Kano stationary phase, about 24-48 h; then dissociated with 1N hydrochloric acid at 60°C water bath for 3 min; colored with modified magenta. It was relatively easy to observe chromosome.2. Root chromosome showed that F011,M05,F1 were diploid ;Meiosis detection showed that F011 is translocated homozygotes and its F1 was translocated heterozygotes.3. The male gamete fertility identification showed that F011 pollen fertility rate was 100%, F1 pollen fertility rate was only 19%, which indicated chromosomal translocation lead to high pollen sterility.4. F1,the seedless watermelon,showed the abnormal variation of endogenous hormones.Compared with F011 and M05,the content of IAA,GA3,iPAs in F1 was lower about 30～70%,while the ABA content was higher about twice in the globular stages.5. The endogene hormone to the embryonic development influence was one after another in the different stage, adjusted the plant character performance together. The possible order was: IAA, iPAs, ABA, GA3.6. Normal growth of seeds possible needed each kind of hormone mutualfunction and dynamical balance. The variations in the ratio of IAA/ABA,ABA/GA3,ABA/iPAs were distinct,showed that the balance of hormones was critical to regulating development of embryo.7. The possible reason of few-seed was that the chromosomal translocation leads to high rates of pollen sterility and endogenous hormone abnormal.8. Single fruit wight, central sugar of F1 plants displayded hybrid superiority. As a result of the chromosomal translocation, seeds reduced nearly 80%, therefore the F1 can be used as an excellent few-seed watermelon variety to apply in bigger area.