Abstract:

The effect of soil water on the growth of callus and bark regeneration of Eucommia ulmoides was studied on the 12-year-old and 25-year-old trees by artificial watering with the levels of I, II, III and IV. The results showed that artificial watering improved the soil water conditions, manifested by the increase of soil water content and water storage capacity in different irrigating levels. 25-year-old trees of E.ulmoides consumed more soil water than those of 12-year-old ones, and made the lower soil water content. Irrigating could accelerate the formation of the callus. The pale green callus were formed in treatment Ⅰ,Ⅱand Ⅲ after 5 days debarking and 5 days earlier than those in control treatment. The thickness of callus of 12-year-old and 25-year-old trees were 1.00 mm and 0.94 mm respectively after 25 days debarking, the growth speed was 0.040 mm·d^-1 and 0.037 mm·d^-1 respectively, and increased 47.1% and 80.8% than those in control. The thickness of regenerated bark in 12-year-old and 25-year-old trees in the treatments ofⅠ,Ⅱ,Ⅲ and Ⅳ increased by 5.0%,22.5%,75.8% and 71.7%, 18.5%,29.3%,80.7% and 95.0% respectively. June was the key period of the growth of regenerated bark and irrigating was most important. The water use efficiency of the trees in treatment Ⅲ was the greatest of all the treatments, increased by 39.3% and 37.4% respectively in 12-year-old and 25-year-old trees compared with the controls. The favorable soil water content in the growing season should maintain between 160～170 g·kg^-1 during growing season.

Key words: Eucommia ulmoides, water supply, callus, regenerated bark