Estimation on the optimal timing of pruning in young sendan

To establish guidelines for the reliable production of straight Melia azedarach timber up to 4 m long without knots or discoloration, the relationship between planting density and pruning time was examined. Artificial M. azedarach stands(3,000 trees ha-1) were pruned 3 years after planting and the branch stubs were removed completely. This resulted in no discoloration around stubs that were below 2 cm in diameter within 1 year after pruning. However, discoloration occurred in 78-100% of branch stubs greater than 2 cm in diameter, which also required more than 2 years for occlusion. There was an average of approximately ten branches(live and dead) per tree and they were distributed around the top, which was 0.2-5.2 m in height for three planting densities(3,000, 5,000, and 7,000 trees ha-1) without pruning for 3 years. The number of branches above 2 cm in diameter and the proportion of live branches were highest in the low-planting-density stand. These results suggest that the optimal timing for pruning of M. azedarach is within 2 years after planting before the diameter of branches and the tree height exceed 2 cm and 4.5 m, respectively. In addition, the optimal planting density of the species is 5,000 trees ha-1 due to the high probability of crooked trunks at lower planting densities.