Effects of Weather Conditions, Tree Vigor, and Pruning on the Early Fruit Drop of Apple
1987
The early fruit drop of ‘Starking Delicious’, ‘Mutsu’, ‘Redgold’ etc. occurred largely in the north of Akita prefecture in 1978. We tried to clarify the effects of weather conditions on the early fruit drop by investigating the weather conditions in 1978, and analyzing statistically the relationship between those in 1979-1985 and the rate of early fruit drop.In 1978, early fruit drop occurred from the 36th day after full bloom. From the 31st day after full bloom the maximum and minimum temperatures were much higher, from the 27th day to the 38th day after full bloom the duration of sunshine was less and the precipitation was more than the mean value of the previous 10 years.The rate of early fruit drop in 1979-1985 was closely correlated with the weather conditions around the 30th day after full bloom; the multiple regression equation which expresses the rate of early fruit drop was obtained using the minimum temperature, the duration of sunshine and the precipitation from the 28th day to the 34th day after full bloom. From these results, it was shown that the early fruit drop was induced by a higher minimum temperature and less sunshine.We also investigated the effects of tree vigor and pruning on the early fruit drop. To estimate the vigor of each tree, elongation of the terminal shoot was measured regularly and the mineral constituents of leaves were analyzed. The rate of early fruit drop was increased in both vigorous and weak trees, and was closely correlated with the elongation of the terminal shoot. Similar results were observed in heavily pruned trees, that is, heavy pruning increased the elongation of the terminal shoot and early fruit drop.
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
9
References
11
Citations
NaN
KQI