A4无核荔枝生理落果规律的观察

以10年生A4无核荔枝树为试验材料,谢花后对其果实生长发育的生理落果状况进行定期观察,以探索A4无核荔枝生理落果规律。结果表明:(1)在整个果实发育过程中,A4无核荔枝存在4次落果高峰期,分别出现在谢花后9~12 d,21~27 d,39~42 d和51~60 d(采收前)。(2)4次生理落果中,第1次落果数量显著高于其他3次,但采前落果期的落果率高达69.84%,显著高于其他3次。(3)4次生理落果期果实脱落的部位均一致,都是在果柄末端的小花穗轴与支轴结合部位脱落。(4)采前落果期单果脱落量比对果高出20%,转黄果(果皮颜色刚转黄)的脱落量比转红果脱落量高出3.65倍,且脱落的转黄果横、纵径及单果重均小于转红果。由此可见,采前落果是造成A4无核荔枝产量损失的主要因素,在果实刚转黄时的小果更容易脱落,在今后生产栽培中应调控后2次落果期尤其是防治采前落果。

Observation of the Regular Patterns of Physiological Fruit Drop of Seedless Litchi A4

T Trees of seedless litchi A4 (Litchi chinensis Sonn.) of 10 years old were used as the experimental material to regularly observe their physiological fruit drops during the fruit growth and development after blossom fall.During the whole process of fruit development,the seedless litchi A4 showed four fruit-dropping peaks which appeared at 9 to 12 days,21 to 27 days,39 to 42 days and 51 to 60 days (before harvest),respectively,after blossom fall.Among the four stages of physiological fruit drop,the number of dropped fruits was significantly higher at the first time stage than at the other three stages.However,the rate of fruit drop at the pre-harvest stage was up to 69.84％,which was significantly higher than that at the other fruit drop stages.The abscission site of physiological fruit drop at the four stages was consistent,and the fruits all fell from the union between the flower axis and the subaxis at the end of the fruit stem.The numbert of single fruit drop was 20％ higher than that of paired fruit drop,and the yellow fruit (fruit peel color turned yellow) was dropped 3.65 times higher than that the red fruit.Moreover,the yellow fruits were lower in transverse diameter,longitudinal diameter and single fruit weight than the red fruits.In this context,the pre-harvest fruit drop was the main factor of the yield loss for the seedless litchi A4.The small fruit was readier to drop when the fruit skin just turned yellow.In the future,attention should be focused on the regulation of the last two stages of fruit drop in cultivation,especially the pre-harvest fruit drop.