Effect of Hot Water Drip Irrigation Treatment of Continuous Cropping Soil Before Replanting on Growth and Yields of Young Japanese Pear Trees

抄録

In the replanting of Japanese pear, the growth of young trees after replanting is often suppressed due to soil sickness syndrome and white root rot. Pre-planting soil disinfection by hot water drip irrigation (HWD) treatment was developed as a control technique for white root rot. In addition, it is also expected to reduce the risk of soil sickness and promote tree growth. We therefore investigated the HWD treatment of pre-planting soil to promote the growth of young trees and obtain high yields at an early stage after replanting Japanese pear. HWD treatment of the pre-planting soil accelerated the growth of young trees in the first two years after planting and increased the yield in the third year compared to untreated soil. The HWD and water treatments of soil lowered the risk of soil sickness syndrome, suggesting that washing out growth-inhibiting substances with water promoted the growth of young trees. The HWD treatment flushed out nitrate-nitrogen from the soil and temporarily increased ammonia nitrogen due to decreased nitrifying activity one day after treatment. However, the change in nitrogen in the soil did not significantly affect growth, and the pH of the soil did not change significantly before and after the treatment. This suggests that the growth-promoting effect was not solely due to changes in soil chemistry, but rather due to the reduction in the risk of soil sickness. These results suggest that HWD treatment of pre-planting soil effectively reduces the risk of soil sickness and promotes the growth of young trees during the replanting of Japanese pear.