Study On Seedless Mechanism Of Two Citrus Cultivars From Vietnam

DaXanh and QuytNgot are two seedless citrus cultivars with high quality breed by Vietnam Hanoi Fruit and Vegetable Research Institute (FAVRI). Investigation of their seedless reason has an important theoretical and practical significance for the promotion of varieties breeding and cultivation measures. In this study, DaXanh pomelo and QuytNgot orange were used as plant materials. To investigate the reason of the two seedless varieties, we conducted studies addressing morphological characteristics, female gametophyte development, pollen germination, identification of ploidy and pollination experiments. The results will provide a theoretical basis for the promotion and cultivation measures. The results showed that:1. The structure of DaXanh pomelo and QuytNgot orange flowers were completely without characteristics of male and female sterility;2. These two cultivars are diploid varieties;3. The pollens germinated in stigma, style and ovary after cross pollination (DaXanh x BuoiDo and DaXanh x Pummelo).The pollen tubes elongated and finally reached nucellus through the micropyle.The average seeds numbe per hybridization fruit was more than67;4. After self pollination (DaXanh x BuoiDo). the pollens germinated in the stigma, while the tubes stopped in style. The pollen tubes were not observed in ovary. It suggested that self-incompatibility was the seedless reason of DaXanh;5. The pollen tubes grew normally after cross pollination (QuytNgot x XaDoai). The process of fertilization was normal.The average seeds numbe per hybridization fruit was28;6. After self pollination of QuytNgot, no pollen tube was observed in stigma, style and ovary. It was also suggested that self incompatibility was the seedless reason of QuytNgot.