A Pruning Criterion for Dormant ‘Niitaka’ Pear Trees that Uses a Decision Tree Model Based on the Basal Diameter of Bearing Branches

Criteria for the selective pruning of pear trees are required at this time as the number of experienced pruning workers continues to decline.The present study aimed to analyze the occurrence of water sprouts and fruit yields according to bearing branch basal diameters and establish pruning criteria for pear trees.During a three-year dormancy period, the lengths and diameters of water sprouts and bearing branches on 'Niitaka' pear trees were measured, and the data were analyzed with Python and R. Bearing branch thickness and sprouting vigor increased with age.Fruit yield initially increased with the bearing branch basal diameter and remained constant thereafter.A correlation analysis of water sprout occurrences and variations in the bearing branch basal diameters identified the explanatory variables used to build a decision tree and establish pruning criteria.A feature importance analysis revealed that the bearing branch basal diameter had the greatest impact on the output of the decision tree.The latter recommended pruning when the bearing branch central and basal diameters exceeded 26.2 mm and 42.3 mm, respectively.We believe that the results of the present study provide guidelines for improving pruning accuracy and efficiency through model-based decision-making.