ISHS Acta Horticulturae 588: II International Symposium on Cucurbits
EFFECT OF CROPPING SEASON ON THE FORMATION OF EMPTY SEEDS IN SEEDLESS WATERMELON RUITS PRODUCED BY SOFT-X-IRRADIATED POLLEN |
| Authors: | S. Watanabe, Y. Nakano, K. Okano, K. Sugiyama, M. Morishita |
| Keywords: | Citrullus lanatus, cropping type, night-time temperature, pollination time, soft-X-rays |
| Abstract:
A new method of producing seedless watermelon fruits by using pollen irradiated with soft-X-rays has been developed recently. This method enables seedless fruits to be produced from any diploid cultivar. To investigate how cropping season affects the formation of empty seeds, we compared July-harvesting culture (JHC) and December-harvesting culture (DHC) in 1999 using ‘Shimaou max RE’ and in 2000 using ‘Fujihikari’. We also examined the effects of pollination time during the day and night-time temperature during the fruit development period on the formation of empty seeds. Empty seeds were categorized as semitransparent, white, or brown. Pollination time influenced neither the number nor the type of empty seeds. The percentage of fruits with brown empty seeds was higher in JHC than in DHC. The proportion of white empty seeds to total empty seeds tended to be higher in DHC than in JHC. The air temperature during the fruit development period was considerably higher in JHC than in DHC. The percentage of fruits that had brown empty seeds was higher at higher night-time temperature. We conclude that the formation of empty seeds is influenced by cropping season, and that high temperature during fruit development stimulates the formation of brown empty seeds, which lower the fruit quality of seedless watermelons. | |
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