Improvement of fruit set and fruit qualities in persimmon 'Fuyu' using pollination

摘要

The Royal Project Foundation has supported research into persimmon (Diospyros kaki Thunb.) production in the highlands of northern Thailand because this fruit is seen as an alternative crop to opium for hill-tribe farmers. The cultivar Fuyu is replacing Xichu, also known as P2, due to its better fruit qualities. However, 'Fuyu' has problems with poor fruit set as well as small fruit size, which are probably caused by low pollination. Since the usual polliniser varieties, eg 'Prince', 'Zenjimaru' and'Gailey', are poorly adapted or not available in Thailand, pollen from P1 (staminate and hermaphrodite flowers), 'Shogatsu' and unknown cultivars grown at the Royal Agricultural Station Angkhang were used. Before pollination, germination of the pollen was checked using the hanging drop technique with two concentrations (15 and 30%) of Brewbaker and Kwack media. The results showed that 15% sucrose gave higher pollen germination than 30% sucrose in all treatments. Pollen from 'Shogatsu' had the highest germination (17.8%) followed by pollen from P1 staminate and hermaphrodite flowers, which were 14.2% and 11.6% respectively. The unknown cultivars had only 3.4% of pollen germination. Fruit set did not differ between treatments (60-90%) and the control treatment had two seeds per fruit, which means that open pollination also occurred. The only difference between the control and the hand pollination treatment was seed number while other fruit characteristics namely, fruit weight, fruit size, fruit firmness and total soluble solids (TSS) did not differ between treatments.