Studies On Overwinter Traits And Main Stem Extension Of Terminal-Buds Of Paulownia Elongata

Paulownia is one of fast growing tree species with most fine timber in China, and it is one of important silviculture tree species in north subtropics and pleasantly warm temperate zone in China, especially, plain region in north China as well. However, in most part of Paulownia cultivation region in China, for Paulownia terminal-buds die in the winter, main stem form of Paulownia is affected seriously by way of its psedodichotomous branching, which results in low rate of Paulownia wood product, Paulownia timber product is lost vastly. The problems above-mentioned are studied in this paper. Paulownia elongata as trial material, its terminal-buds death mechanism is studied by testing index of humidity physiology and creature membrane penetration, etc. and the possibility ways of terminal-buds' living through winter were studied. Results are follow: a) That natural main stem extension of P. elongata by adventitious doesn't tally with demand of production and that the only way of stem form cultivation is successive main stem extension by terminal-buds are considered, b) Lethal temperature of terminal buds is -15 °C within 72 h, the lateral buds within 96 h and the shoots within 96 h. In the natural condition, the temperature does not occur in the region of the tested seedlings in some years, but the terminal-buds die. c) Young stem, passage of terminal-buds obtaining humidity, because of its badly keeping water power, is the restrict factor for terminal-buds obtaining humidity, Terminal-buds have anti-drought mechanism of delaying dehydration with low water power, and die of water coercing, d) If seedling buried in soil, the terminal-buds can live through the winter. If the buds are covered with plastic bag and covered with paper bag in nature, no matter what filling is, all terminal-buds can't live through winter; but if covered with paper bag and compensated with water, a few buds can live through winter, e) Filling with polyacrylamide can make less the times to compensate with water for terminal-buds, f) Shoot rate of the buds is very few. There may be the reasons for terminal-buds losing water during early spring.The creative of this studies is as follow: The dying reasons of Paulownia terminal-buds are elucided for the first time, terminal-buds may die of water coercing. The way of P. elongata terminal-buds living through the winter by artificial support are put forward, and main stem extension by terminal-buds is realized...