STUDY ON YIELD INDEX OF YOUNG BEARING TREE OF JUGLANS REGIA

In a study conducted in the arid and hilly region, Fenyang of Shanxi Province, China, the stem diameter and vertical projection area of tree crown were measured to study their relation with yield in young bearing walnut trees of different cultivars. Five lateral bearing cultivars were used including Liaoning No. 1, Luguang, Xiangling, Zhonglin No. 1, Jing 861. Two terminal bearing cultivars Jinlong No. 1, Gift No. 2 were also used. The results showed that there were significant positive correlations among stem diameter, vertical projection area and yield. The loading capacity of young bearing trees was reflected by stem diameter or vertical projection area. The amount of bearing branches and vegetative branches also exhibited a close relation with yield in young bearing trees. The high and steady yield depended on having a 0.5–0.9 cm diameter bearing branch, 20–30 cm in length of vegetative branch and a rate of 5–10% of bearing vs. total branches in lateral bearing cultivars, and in terminal bearing cultivars on 0.5–0.9 cm in diameter of bearing branch, 30–40 cm in length of vegetative branch and a rate of 60%. It was suggested that trees should be pruned to keep moderate vigor.