黄金香柳对水分胁迫的生长与生理响应

Growth and Physiological Responses of Melaleuca bracteata cv.‘Revolution Gold' to Water Stress

以2年生黄金香柳为试材,采用盆栽方式人工模拟土壤干旱条件,设6个水分处理梯度,即土壤含水量分别为饱和持水量的100%(饱和持水量)、80%(正常浇水对照)、60%(轻度干旱)、40%(中度干旱)、20%(重度干旱)、10%(极度干旱),研究不同水分条件下黄金香柳生长和生理指标的变化特征。结果显示:(1)与正常浇水对照相比较,饱和持水量处理对黄金香柳的株高、冠幅、叶面积均无显著影响,轻度干旱胁迫仅对其冠幅产生轻度限制,随着干旱胁迫程度的进一步加剧,黄金香柳各指标的生长均受到显著抑制。(2)不同程度干旱胁迫条件下,黄金香柳叶片干重、干鲜比以及比叶重与对照无明显差异,而其叶形态指数显著降低。(3)随着干旱胁迫水平的加重,黄金香柳叶片可溶性糖(Ss)、游离脯氨酸(Pro)和丙二醛(MDA)的含量显著增加,并随胁迫时间的延长表现为先增大后减小的变化趋势;叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性均随干旱胁迫时间的延长先升高后降低,但在试验末期与对照无明显差异;叶片叶绿素(Chl a+b)含量随着干旱程度的增强逐渐增加,且明显高于对照。研究表明,黄金香柳的生长在干旱胁迫条件下受到不同程度的抑制,但其能够通过增加叶绿素的含量来保证其光合作用的正常进行,减轻干旱伤害;黄金香柳还能通过减小地上蒸发面积,增加Ss、Pro含量以及SOD、CAT活性适应干旱胁迫环境,即使在极度干旱胁迫[实际含水量(4.42±0.82)%]下也未出现植株死亡的现象,从而表现出较强的干旱忍受能力。

Taking 2 years old Melaleuca bracteata cv. ＇ Revolution Gold as the test materials, using potted approach simulate soil drought conditions,we set 6 levels of water supply treatment. They are 100% satu- ration soil moisture,80%（normal watering）, 60% （light drought）, 40% （moderate drought）, 20% （severe drought） and 10% （extreme drought）, respectively, we studied its growth and physiological characteristics under different water treatments. The results showed that： （1）The plant height,crown width and leaf area were grew well under 100% saturation soil moisture condition, but had no significant difference compared with the control. Only their crown width slightly declined in 60% saturation soil moisture,but the growth were greatly reduced with the intensifying stress （2） Under drought stress, the dry weight, dry weight/ fresh weight and specific leaf weight had no significant difference compared with the control hut the leaf modal traits greatly decreased; （3）With water stress intensifying, Ss, Pro and MDA contents in the leaves all showed a tendency to increasing; they were firstly increased and then decreased with time. With the ex- tension of stress time, the activities of SOD and CAT in the leaves increased first and then decreased, but had no significant difference compared with the control at the end of the experiment. Drought stress significantly increased the content of chlorophyll（Chl a＋h）. The result indicated that the growth of M. bracteata cv. ＂Revolution Gold＇ were inhibited in different degree of drought stress,but they could ensure the normal photosynthesis by increasing the content of chlorophyll, mitigating drought damage. However, there was no mortality even under extreme drought stress F the actual moisture content（4.42 ~ 0.82）~ 1, which indicated that the shrubs tolerate drought by reducing leaf area while increasing the contents of Ss, Pro and the activ- ities of SOD and CAT enzymes.