钾肥对白桦生理特性及三萜含量的影响

为了研究钾肥对白桦防御酶及三萜含量的积累，从而建立生产三萜为目的的白桦栽培技术，建立钾肥调控三萜合成体系，以2年生白桦幼树为试材，通过施加高（15 g/盆）、中（10 g/盆）、低（5 g/盆）3种钾肥（KCl）对白桦进行处理，分析白桦叶片总三萜积累变化，同时对相关抗逆酶进行检测。结果表明，施用钾肥能够不同程度地提高白桦叶片中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）以及过氧化物酶（POD）的活性，并使叶片中可溶性糖含量增加，其中以中浓度钾肥效果最好，可使三萜含量达42.16 mg/(g?DW)。在生长旺盛季节7-9月（哈尔滨），对白桦实施中浓度钾肥，可有效促进白桦叶片中三萜含量的积累。

The Effects of Potassium Fertilizer on Physiological Characteristics and Triterpene Contents in Betula platyphylla Suk.

In order to study the effects of potassium fertilizer on the activities of defensive enzymes and triterpene accumulation in the leaves of birch which paved the way for establishing a cultivating system of birch to produce triterpene via potassium application. 3 doses of potassium fertilizer （KC1）, 15 g, 10 g and 5 g were applied to 2-year seedlings. Then the content of triterpene and the activity of defensive enzymes were determined by a spectrophotometer. The results showed that potassium fertilizer raised the activity of SOD, CAT and POD to different extent, respectively. The content of soluble sugar within the leaves also rose. Among the three doses, the mediate one （5 g） brought the best effect to triterpene accumulation up to 42.16 mg/（g. DW）]. Mediate potassium could effectively promote the accumulation of triterpene within the leaves of birch when were fertilized during the seasons for fast growing （from Julv to September in Harbin）.