ISHS Acta Horticulturae 587: International Symposium on Asian Pears, Commemorating the 100th Anniversary of Nijisseiki Pear
SERPENTINE-TYPE TRELLIS TRAINING OF JAPANESE PEAR - TRAINING METHOD AND FRUIT PRODUCTIVITY |
| Author: | A. Kaminaka |
| Keywords: | Kousui, yield, tree form, planting density, light-interception characteristic |
| Abstract:
In recent fruit growing, it becomes important to simplify the technical skill and reduce the intensity of work. The serpentine-type trellis system solves inconvenience in the flat-type trellis, increases work efficiency, and reduces working hours. In this study, the serpentine-type trellis system was further developed. To improve training methods using the serpentine-type trellis, three types (Type A, B, C) of training methods were compared with the open-center training method using the flat-type trellis. Besides, effects of planting distance were investigated. The training period to establish the tree form in the serpentine-type trellis system is much shorter than that in the flat-type trellis system. Thus the serpentine-type trellis system exceeded the flat-type in initial yields. However, yields by Type A and B training methods using the serpentine-type trellis hardly increased during the high productive ages. Besides, under the same fruit set condition, fruit sizes in Type A and B were smaller and more varied than that in the flat-type. There are possibly two primary factors that cause the problems. One is heavy pruning. Generally, pear trees need proper crowns according to their vigor and age. However, since Type A and B training methods in which the trunk or the primary scaffold branches are trained vertically and not allowed them to grow over the trellis, the crowns were restricted within the narrow planting distance. Therefore, excessive pruning was needed for aged trees. The heavy pruning also negatively influenced the fruit growth and quality. Another reason was a defect in the tree form by the training methods using the serpentine-type trellis. The tree form (Type A, B) in which lateral branches were horizontally trained to the serpentine type trellis was inferior to the form using the flat type trellis in light-intercepting characteristics. Because the inside of the serpentine-type trellis was much darker than the outside and the lower lateral branches could not receive so much sunlight as the upper ones. The flat-type trellis system that can receive sunlight uniformly and efficiently is excellent for the horizontal training of lateral branches. Type C training method in the serpentine type trellis system in which primary scaffold branches were trained horizontally and lateral branches were trained vertically, could keep tree vigor properly by extending their primary scaffold branches. Furthermore, the fruit size in this training method was comparatively uniform because of an advantage in the light interception of lateral branches. Therefore, Type C training method could be the most suitable and hopeful for the serpentine-type trellis. | |
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