NAGASAWA, Katsuo

The Effect of 1-(1-Naphthaleneacetyl)-3, 5-dimethylpyrazol (TH 656) on Fruit Thinning in Satsuma Orange I. Fruit Thinning Effects of TH 656 in Relation to Shoot Length and Fruit Position. by Y. NOMA and K. NAGASAWA. Faculty of Horticulture, Chiba University, Matsudo, Japan. Tech. Bull. Fac. Hort. Chiba Univ., No. 19: 7-12, 1971. Investigation on the chemical thinning effects as affected by fruiting position in the tree crown and shoot length in Early Satsuma Orange (Citrus Unshiu MARC. cv. Miyakawa wase) were carried out during the year 1969-1970. Chemicals used in this study were TH 656 (50, 100, 200 and 400ppm solution) and NAA (300ppm solution). In the case of TH 656, spraying was done twice separately on the 10th and 30th day after full bloom and NAA spray was applied on 30th day. TH 656 (100ppm) and NAA (300ppm) treatments gave 6-10 0x1.36334p-890nd 7-11-0.000000ruit set, re spectively. In the control plot, the upper part of tree crown and longer bearing shoots gave higher percent fruit set than the lower part of tree crown and shorter bearing shoot. On the other hand, TH 656 treatment induced heavier fruit drop in the upper part in the crown and longer shoots. Therefore, the difference between the fruit set on the upper and lower parts in the crown and long and short shoots was reduced considerably. TH 656 treatments at 200 or 400ppm caused heavy fall of fruits. But no injuries were observed on the first flush and flowering in next year.