疏果剂敌百虫在‘金冠’苹果短果枝内的分布和对光合强度及产物分配的影响

‘金冠’苹果盛花后14天喷施1200ppm敌百虫可以引发落果,在短期内抑制幼果的生长。根据幼果在短果枝上的发育与坐果特征的不同,可分为三类:中心果、初生边果和次生边果。~(14)C-敌百虫示踪实验表明,敌百虫在维管束和幼果中含量高。敌百虫喷施48小时后,短果枝莲座叶的光合作用显著地受抑制,同时运向幼果的~(14)C-同化物显著减少,光合作用在8至18天内恢复正常。作者认为,敌百虫疏果的机制是减弱“源”、“库”的强度,加剧短果枝内碳水化合物短暂缺乏,使较小的幼果因碳水化合物缺乏而减缓生长,直至脱落,达到疏果的目的。

THE DISTRIBUTION OF FRUIT THINNER DIPTEREX IN THE SPURS AND ITS INFLUENCES ON PHOTOSYNTHESIS AND DISTRIBUTION OF PHOTOSYNTHATE OF 'GOLDEN DELICIOUS' APPLE

Sprayed on 'Colden Delicious' apple 14 days after full bloom,1200 ppm dipterex induced fruit abscission.The growth rate of fruitlets was significantly inhibited 4 days after treatment, but it became the same as the check after "June drop". The fruitlets on a spur can be classified as central, primary and secondary lateral ones according to their position on the spur. The central and primary lateral fruitlets developed earlier, and are larger in diameter, larger in their subtending spur leaves size, faster in growth rate than the secondary lateral ones, and were more difficult to be thinned by dipterex. The central fruitlet was the most difficult to be thinned. Employing ~(14)C isotope techniques, it was found that ~(14)C-dipterex accumulated in the vascular bundle cells. The photosynthesis of spur leaves was inhibited significantly 48 hour after dipterex spray. This inhibition disappeared on the 18th day after spray. Experiment with ~(14)C-photosynthasis showed that 4 days after dipterex spray, the concentration of ~(14)C-photosynthasis in the spur leaves was significantly higher than that of none-treated check, and that the photosynthasis which accumulated in the fruitlets were reduced significantly. From the above results, it is proposed that the mechanism of fruit thinning effect of dipterex involves the following processes, the physiological function of vascular bundle cells is probably inhibited because of dipterex accumulation. Consequently, the translocation of carbohydrates to the fruitlets is reduced.Gradually,being a weak sink,the smaller fruitlets stop growing because of a deficiency of carbohydrates, and finally, abscise.