Study On The Fertility Of Citrus Somatic Hybrid And The Fruit Development Of Empty-seed Pummelo

The interspecific somatic hybrid [Rough lemon+ 'Hamlin' sweet orange] was used as experimental material in the fertility research. Its flowering character, pollen fertility and storage condition were observed. To put the productive technology of empty-seed pummelo fruit into practice, the interploid cross of HR with Wanbai pummelo was conducted. The course of triploid seeds development was observed, and the changes of GA, ABA content in seeds, flesh of HR pollinated fruit were detected .Main results are as follows:1. HR had three types of flowennormal. pistil abortive and abnormal flower. And their percentage was differntly great.2. Compared to the corresponding parents, HR was fertile, with intermediate pollen stainability (77.41%), germinability (15.31%) and pollen numbers per anther (19229.40). But the percentage of small pollen (25.67%) was much higher than the corresponding parents ('Hamlin' was 0.70%, Rough lemon was 3.80%).3. The suitable storage condition for HR pollen was low temperature(-20癈). low humidity (<50%) and vocauum.HR pollen germinability decreased to 8-10% after one year's storage.4. The fruit set percentage of HR stored was 45.75% which was not significantly different with that of fresh pollen.5. The course of seed development of HR pollinated fruit was observed. The results indicated that: (1) The ploidy level and development stage of seeds were different. Even if the ploidy level of triploid seeds was indentical, their development stages were different; (2) The degeneration of cotyledons was the main character of degenerated triploid zygitic embryos: (3) The abortive stage of triploid seeds focused on 90~100 days after pollination.6. The changes of GA, ABA in seeds, flesh of HR pollinated fruit showed that: With the degeneration of tetraploid endosperm, triploid zygitic embryos gradually degenerate from 80 days after pollination. At the same time. GA content decreased and ABA content increased in seeds; GA content changed greatly in flesh, but ABA content slowly increased with the development of HR pollinated fruit.7. Compared with Wanbai pummelo check fruit, HR pollinated fruit significantly decreased the quantity of well-developed seeds and increased weight per fruit and improved fruit quality; And also significantly improved the ratio of soluble solidsxitric acid, the ratio of total sugars:citric acid and the flavor of Wanbai pummelo.