土壤干旱胁迫下沙棘休眠、萌芽期内源激素变化及外源GA_3的调节

研究了２年生中国沙棘（Ｈｉｐｐｏｐｈａｅ ｒｈａｍｎｏｉｄｓ）在土壤干旱胁迫下苗木含水量、内源激素水平与萌芽率关系以及萌芽关键期喷施外源ＧＡ３的作用。结果表明：土壤干旱胁迫使冬季休眠与春季萌芽期苗木含水量、内源ＧＡ１／３降低，内源ＡＢＡ明显提高，ＧＡ１／３ＡＢＡ下降，达到萌动所需的调控阈值的时间延迟，重度干旱下苗木萌芽延迟约２５ｄ，且萌芽后的枝生长十分缓慢；中度干旱下苗木萌芽延迟１０ｄ，萌芽后生长亦有所抑制。喷施８０ｍｇ／Ｌ外源ＧＡ３溶液可有效提高重度干旱下苗木内源ＧＡ１／３，降低ＡＢＡ含量，使ＧＡ１／３／ＡＢＡ提高，促进苗木提早萌芽及萌芽后生长；在适宜水分及中度干旱下，沙棘苗木外施ＧＡ３对萌芽及其生长作用不明显。

Changes of Endogenous Hormone of Sea buckthorn in Dormancy Stage and Sprout Period under Soil Water Stress and Exogenous GA_3 Regulation

This paper deals with the relationship among water content.endogenous hormone and sprout rate of two years old China sea-buckthorn under soil water stress. The effect of spraying exogenous GA3 in critical time was also researched. The main results show that water content and endogenous GA3 decreased due to water stress, in the meantime endogenous ABA increased evidently during dormancy stage in winter and sprout period in spring, which lead to the ratio of GA1/3/ABA fell and reached threshold value later. Seedlings under serious water deficit sprouted 25 days later compared to that of control and grew slowly after sprout. Sprout date of seedlings under medium water deficit was postponed about 10 days and growth after sprout was limited slightly. Spraying exogenous 80 mg/L GA3 solution can increase endogenous GA1/3 and GA1/3/ABA of sea-buckthorn with ABA content declining under serious water deficit, so sprout date and growth was promoted effectively. However, spraying exogenous 80 mg/L GA3 solution had little effect on seedlings under appropriate water content and medium water content.