百里香对干旱胁迫的形态及生理响应

Morphological and physiological response of thymeplants characteristics to drought stress

摘要:

采用称重控水干旱法,对盆栽百里香(Thymus mongolicus)幼苗进行4个不同梯度的干旱胁迫处理,即适宜生长含水量(对照),轻度胁迫,中度胁迫,重度胁迫,测定了百里香的形态指标及生理指标。结果表明:(1)随干旱胁迫增加百里香的株高、叶面积减小。(2)百里香根组织可溶性蛋白质含量变化区别于叶和茎组织的变化,在相同胁迫时间下,随着干旱胁迫程度的加大其含量呈下降趋势。百里香根部的蛋白质平均含量与茎中的含量接近,为5.07 mg/g,小于叶组织的可溶性蛋白质含量。胁迫7 d时,重度和中度干旱胁迫与对照组相比差异显著(P＜0.05)。(3)随着胁迫程度的增加及胁迫时间的延长,百里香不同组织丙二醛含量增加。在处理前平均含量为18.24 μmol/g,小于茎组织含量但大于叶组织。(4)叶、茎、根各组织中可溶性糖含量都随着胁迫强度的增大而增加。在胁迫到达14 d时,各处理可溶性糖的含量达到最大,其中重度胁迫下(根组织)含量达77.9%,胁迫21 d时可溶性糖含量减少。(5)百里香叶片组织重度干旱胁迫7 d时,脯氨酸的增长最大,为初始值的2.3倍,随后又降低,与对照相比达到极显著水平。(6)同一胁迫梯度下,茎和根中超氧化物歧化酶(SOD)活性随着时间的延长先增加后降低,而随着干旱胁迫强度和时间的延长,植株根、茎、叶组织的过氧化物酶(POD)活性减弱。

Abstract:

In this experiment, the method of weighing and controlling water was used, the seedlings of Thymus mongolicus Ronn were treated with four different gradients of drought stress, suitable growth moisture content (control), mild stress, moderate stress, and severe stress. By measuring the morphological index and physiological index of thyme, the law of its change under drought stress was analyzed to provide theoretical basis for its application in landscape architecture. The results show that:(1) Thyme could adapt to drought stress by reducing plant height growth, leaf area growth and increasing root-cap ratio.(2) The change of soluble protein content in thyme root is different from that in leaf and stem, under the same stress time, the content of soluble protein in thyme root tissues showed a decreasing trend with the increasing of drought stress degree. The average protein content of thyme roots and stems was close to 5.07mg/g, less than the soluble protein content of leaf tissues. At 7 days of stress, the difference between severe and moderate drought stress and control group was significant (P＜ 0.05).(3) The content of thyme in different tissues increased with the increase of stress degree and the extension of stress time. The content of malondialdehyde in root tissues is 18.24μmol/g until the thyme was treated, which was lower than that in stem tissues but higher than that in leaf tissues.(4) The soluble sugar content of thyme leaves, stems and roots increased with the increase of stress degree. At 14 d of stress, the soluble sugar content of each treatment reached the maximum, among which the content of root tissue reached 77.9% under severe stress.But the soluble sugar content decreased with the increase of stress days.(5)The content of proline in thyme leaves was the highest, which was 2.3 times of the initial value at 7 days of severe drought stress. Then the content decreased, and reaching a very significant level compared with the control.(6) Under the same stress gradient, SOD activity in stem and root increased with the extension of stress time. With the extension of drought stress intensity and time, the POD activity of roots, stems and leaves decreased.