胚珠異常導致 ‘水晶拔’番石榴少籽並施用GA3提升其著果率

Abstract

‘Shuei Jing’ guava (Psidium guajava L.) is an almost seedless cultivar with great potential in Taiwan, but its fruit set and yields are usually low. I studied the cause of seedlessness and the way to increase fruit set in ‘Shuei Jing’ . Different types of pollination and pollen donors were tried for investigating seed number in ‘Shuei Jing’ and ‘Jen Ju’ guava. When ‘Shuei Jing’ was the pollen acceptor, the seed number was significantly less than that of ‘Jen Ju’. However, ‘Shuei Jing’ served as pollen donor resulted in more than 300 seeds when ‘Jen Ju’ was the pollen acceptor. It indicated that pollens in ‘Shuei Jing’ were sufficiently functional for seed formation. The meiosis of microsporocyte was examined in ‘Shuei Jing’. In metaphase I, pollen mother cells with 11 associated bivalent in ‘Shuei Jing’ were as normal as those in ‘Jen Ju’. However, some of pollen mother cells showed aberrant chromosomes in ‘Shuei Jing’. The percentage of normal association, trisomics, and reciprocal translocation were 51.2, 17.4, and 4.0 respectively in ‘Shuei Jing’. There were at least 50% of pollens with normal number and structure of chromosomes in ‘Shuei Jing’. Furthermore, pollination with ‘Shuei Jing’ pollens resulted in numerous seeds in ‘Jen Ju’. These results suggested that pollens were not the main cause of seedlessness in ‘Shuei Jing’ guava. The morphology and structure of embryo sac in ‘Shuei Jing’ were investigated. There were 13.7% of ‘Shuei Jing’ with normal embryo sacs and were significantly less than those of ‘Jen Ju’. The abnormal ovules were classified in four types. NCAE meant the embryo sac with normal central cells but abnormal egg apparatus. ACE meant both central cells and egg apparatus were abnormal in the embryo sac. NES meant no embryo sac within an ovule. OT meant other few abnormal types of ovules. There were 50.4% ovules of ‘Shuei Jing’ belonged to NES and were significantly higher than those of ‘Jen Ju’. These results suggested that high percentage of abnormal ovules might be responsible for seedlessness in ‘Shuei Jing’. GA3 was applied to the flowers of ‘Shuei Jing’ guava to increase the fruit set. GA3 applied on the day of flowering increased the fruit set in 2007. The percentage of fruit set reached 70% in the treatment by GA3 at concentration of 100 ppm on 42 days after flowering (DAF). However, the percentages of fruit set among all treatments were not significantly different when fruits reach maturation. Applied on the day prior to flowering, 14 and 28 DAF with GA3 at 50 ppm and 100 ppm in 2008, the percentage of parthenocarpic fruit and fruit set reached 51% and 63% respectively and significantly higher than that of control. Even GA3 treatment resulted in tumorous appearance and delayed fruit maturation it still enhanced the fruit number, size, and yield in ‘Shuei Jing’ guava.