Effects of Various Training Systems on Fruit Production Efficiency in Young Filler Trees of Japanese Pear ‘Gold Nijisseiki’

Abstract

For the purpose of obtaining early and high yield in young filler trees of Japanese pear ‘Gold Nijisseiki’ the effect of different training systems on fruit production efficiency was investigated. Permanent trees with 3 scaffolds (PT) and filler trees with 6 different tree forms, that is, 3 scaffolds (3-SF), 4 scaffolds (4-SF), 6 scaffolds (6-SF), improved-two-branch 8 scaffolds (I-8-SF), 8 scaffolds (8-SF) and improved-two-branch 12 scaffolds (I-12-SF) were compared. Fruit production efficiency was evaluated by three indicators: yield per canopy area, yield per leaf area, and yield efficiency (yield per trunk cross-sectional area). Yield per 1 m² of the canopy area was higher in the training systems with larger numbers of scaffolds. The average yield from 6–8-year old trees of I-12-SF was 4.1 kg, showing an increase of 44% compared to PT. Yield per 1 m² of leaf area was also higher in the training method with larger numbers of scaffolds. Average yield from 6–8-year-old trees was 1.8 kg in the I-12-SF, which was 35% higher than in the PT. Yield efficiency was also higher in the training method with larger numbers of scaffolds. Average yield efficiency of 6–8-year-old trees was 1,232 g/cm² in the I-12-SF, which was 60% higher than in the PT. These findings showed that fruit production efficiency was higher in training systems with larger numbers of scaffolds, due to higher density of spur bearing wood in the canopy, higher percentage of spur leaves which make a great contribution to fruit production, and lower shoot growth.