Efficient production for processing apples by inducing alternative bearing in columnar trees and using improved harvesting methods

Abstract

To meet the increasing demand for domestically produced apples for processing, we investigated through simulation whether it was possible to cultivate apples to an annual yield of 8t/ 10a using columnar apple trees while reducing labor hours by more than 60%. Stable yields could be obtained every year by systematically shifting the year of fruiting and the year of nonfruiting for each row of trees utilizing the characteristics of alternative bearing in the columnar trees. When the trees were managed so that 3 or more fruitlets were left within a cluster without thinning, the trees would have a heavy crop load and be induced to alternative bearing cycles. It was estimated that even if the half of the trees in the orchard at a high planting density (570 trees/ 10a) did not bear fruit, the yield would be about 10t/ 10a. The fruit quality declined as the crop load increased, but the fruit weight and soluble solid content were maintained at 150g and 10 ºBrix, respectively, even after overfruiting. The harvesting time was shortened by collecting a large amount of fruit by dropping them onto a net spread under the canopy. It was estimated that annual labor hours could be reduced by more than 60% by omitting the fruit thinning and coloring operation and shortening the harvest time. The cultivation method in this study has great potential for apple production for processing because it is possible to increase the yield with labor-saving management.