干旱胁迫对两种速生树种叶绿素含量的影响

以竹柳和尾巨桉2种速生树种为试材进行干旱胁迫模拟盆栽试验,通过对比干旱胁迫后叶片中叶绿素a、叶绿素b、叶绿素（a＋b）含量以及叶绿素（a/b）值的变化,对供选树种进行抗旱性能分析与评价,为在华南地区选育优良的抗旱、节水速生树种提供重要的理论支持和参考依据。试验结果表明,两个树种在干旱胁迫下均表现出叶绿素a含量逐渐降低的趋势,尾巨桉降幅为70.2%,竹柳为55.5%;叶绿素b、叶绿素（a＋b）含量先缓慢增加后降低,叶绿素b含量与正常水分条件相比变化较小,叶绿素（a＋b）含量的变化主要由叶绿素a引起,竹柳的叶绿素（a＋b）含量变化幅度小于尾巨桉。叶绿素（a/b）值呈现先降低后升高的变化趋势,最小值均出现在干旱胁迫第9 d,且竹柳的降幅小于尾巨桉。经过对各项指标的综合分析并结合植物的抗旱性表现,得出竹柳比尾巨桉的适应性强,抗旱性能较好。

Effects of Drought Stress on Chlorophyll Content of Two Fast-growing Tree Species

Using bamboo willow and Eucalyptus urophylla × E. grandis seedlings as test materials, drought stress experiments were conducted using a pot-culture method to study theories and mechanisms for water-saving fast-growing tree species in southern China.The test trees were analyzed and evaluated by comparing the changes of chlorophyll a, chlorophyll b and chlorophyll（a＋b） contents as well as the ratio of chlorophyll（a＋b） ratio in the seedlings after being stressed by drought, Results showed that the contents of chlorophyll a from the test trees of both species decreased gradually after drought stress treatment; E. urophylla × E. grandis declined to 70.2%, whereas bamboo willow declined to 55.5%. The content of chlorophyll b and（a＋b） increased at first but then decreased; chlorophyll b content changed little compared with that under conditions of normal water availability; the change of chlorophyll（a＋b） content was mainly caused by changes that occurred in chlorophyll a. Bamboo willow＇s chlorophyll（a＋b） varied less than that in E. urophylla × E. grandis. Chlorophyll（a/b） showed a trend that first decreased and then increased, the minimum values being on the 9thday of drought stress; the minimum for this parameter in bamboo willow was lower than in E. urophylla × E. grandis. Through comprehensive analyses of every indicator combined with the drought resistance performance of plants, it was concluded that the bamboo willow had better adaptability and drought resistance performance than E. urophylla × E. grandis.