Effect of ‘joint cutting’ and positional difference on new shoot growth and uniformity of fruit quality in tree joint training system of Japanese pear ‘Housui’

In tree joint training system, vegetative growth throughout tree canopy is known to be equalized by grafting trees together.
Furthermore, this training system is also expected to have better uniformity of fruit quality within tree canopy, but it is still unclear.
Therefore, this study aimed to reveal the factors that affect fruit quality and its uniformity by ‘joint cutting’ (graft union reseparation of main branch) and new shoot management.
Moreover, detailed positional information of fruits and current shoots was measured to investigate whether that would be additional factors to explain the variation of fruit quality and difference of new shoot growth throughout tree canopy.
Variation of fruit quality parameters except weight became small in joint trees compared to those of joint-cut trees with pinching.
Fruit quality parameters positively correlated with distance from main trunk were total soluble solids (TSS) both in joint trees and joint-cut trees.
Acidity was negatively correlated with distance from main trunk in joint-cut trees.
TSS was positively correlated with distance from main branch in joint-cut trees.
New shoot growth through basal to apical part of main trunk tend to become smaller in joint-cut trees than joint trees.
These results suggest that joint cutting change equalized vegetative growth throughout tree canopy into not equalized state and make variation of fruit quality bigger.
Future studies need to evaluate the effects of annual changes and relationships between fruit quality and new shoot growth by conducting continuous research in joint-cut trees.

IV Asian Horticultural Congress – AHC2023

K. Iimura, Y. Sekozawa, S. Sugaya

Pyrus pyrifolia, tree joint training system, graft union reseparation, positional information

https://doi.org/10.17660/ActaHortic.2024.1404.162