モモの生理的落果と果実発育との関連

In order to clarify the factors that cause fruit pit-spilitting and physiological fruit drop in peach (Prunus persica cv.'Shimizu-hakuto'),the effects of fruit thinning on fruit development were investigated.In addition,the characteristics of fruit development in 'Shimizu-hakuto'were compared with those in early-ripening cultivars which cause heavy pit-splitting but low physiolofical fruit drop,and in 'Yamao-hakuto'which hardly cause any pit-splitting or physiological fruit drop.Pit-spilit and fallen fruits genarally show a rapid enlargement at the end of stage Ⅰof fruit growth than normal fruits.At completion of pit splitting the percentage dry weight content of the pit reached 30%. Fruit with relatively less increase in length that of diameter and width,at the early stage of the fuit development,showed low pit-splitting occurrence in all the cultivars.Early in the stage of fruit development, we observed two vascular bundles attached to the seed of the early-ripening cultivars,but only one in 'Shimizu-hakuto'and'Yamato-hakuto'.Embryos in pit-spilit fruit were smaller than in normal fruit,and their length in fallen fruit was less than 5mm.The development of endosperm was also delayed in fallen fruit.