Effect of growth under full sun after removal from dark-storage on fine root growth ability of containerized sugi (Cryptomeria japonica) seedlings

Abstract

Dark-storage at room temperature can stop the elongation growth of containerized sugi seedlings during the growth period. The inability of photosynthetic production in the dark has a negative impact on seedling vigor such as fine root growth ability. In this study, we aimed to determine the growth period under full sun necessary for the recovery of fine root growth ability of containerized sugi seedlings after 4 weeks of dark-storage. In the summer of 2021, after 4 weeks of dark-storage, there were 0, 1, 2, or 4 weeks of growth under full sun, and all the seedlings including the seedlings that were not stored in the dark (control) were planted on the same date in early August. One week after planting, all the seedlings were dug up and the dry weights of elongated fine roots that had grown into the soil was measured. The seedlings without the growth under full sun after the dark-storage showed the smaller dry weight of elongated fine roots for one week after planting compared to the control seedlings without the dark-storage. The dry weight of elongated fine roots of the seedlings grown under full sun for more than one week after the dark-storage was not significantly different from that of the control. It was suggested that the reduction in fine root growth ability caused by the dark-storage could be restored by growing the seedlings under full sun for more than one week after the dark-storage.