茶樹における授精結実に関する研究

(第3報) 開花期と落顆について

抄録

It was already shown by the writers that only 20 o of the flowers succeeded to mature fruits in Thea sinensis L. though about 90% of the ovules formed embryo-sac and about 80% of them were fertilized in the best flowering period. (1955) But it was also indicated that in the early flowering period the percentage of the embryo-sac formation was remarkably low and that only in the late flowering period the decrease of the fertilization was found. (1956)
It was already found that the percentage of the fruit drop was high in the process of seed-formation, so in the present investigation particular attention was given to a study of the relation between the flowering period and the dropping behaviour of fruits.
The varieties " Yamatomidori " and "Yabukita " were used as material.
The results were as follows :
1) There were three waves of fruit-dropping during the seed-formation. (see Fig. 1)
As Table 1 shows, the first wave took place from the end of early flowering period to the beginning of the best flowering period, and about 20% of flowers fell in this period. It was fairly said that the appearance of the first wave was, when cytologically observed, due to the scarcity of perfect embryo-sac.
The second wave of fruit dropping was seen in winter. It seemed that both in the best and in the late flowering period the seed formation was prevented remarkably by low temperature.
The third wave of fruit dropping was observed in April and May, when the malnutrition of seed growth was caused by the growth of buds.
2) Flower thinning was tried for the purpose of preventing the fruit dropping at each flowering period but in vain, as Fig.2 (a-d) shows, except the noticeable phenomenon observed at the third flowering period. (see Table 2)