荆芥的生长、渗透调节和抗氧化能力对干旱胁迫的响应

Growth,osmotic adjustment and antioxidant capacity responses of Schizonepeta tenuifolia to drought stress

采用盆栽控水试验,研究荆芥的生长、渗透调节和抗氧化能力在不同干旱程度[基质相对含水量分别为5%~10%(重度干旱)、45%~50%(中度干旱)和85%~90%(正常灌溉)]和不同干旱时间(15、30和45 d)下的响应。结果表明,随着干旱程度的加深,荆芥的生长受到抑制,生长速率、叶干重和叶绿素含量降低,比叶质量增大;叶中渗透调节物质的积累增加,可溶性糖、可溶性蛋白、脯氨酸和Na^+含量增大;叶片抗氧化能力受到影响,其中超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性在胁迫15和30 d时逐渐增强,45 d时逐渐减弱,过氧化物酶(POD)活性则在胁迫30和45 d时逐渐增强,总酚和总黄酮的含量在胁迫15 d逐渐增大,分别在30和45 d时中度干旱下的积累量最高。随着干旱胁迫时间的延长,荆芥叶的渗透调节作用受到影响:可溶性糖、可溶性蛋白含量升高,脯氨酸、K^+、Na^+和Ca^2+的含量降低,SOD和CAT活性先增强后减弱,POD活性持续增强,总酚和总黄酮的含量先增加后趋于不变。荆芥能对干旱胁迫做出适应性应答,对缺水环境具有一定的耐受性,这为荆芥的规范化栽培和用水管理提供了依据。

This research studied the changes(relative to unstressed plants)in the growth,osmotic adjustment and antioxidant system of Schizonepeta tenuifolia grown in pots under severe or moderate water deficit stress[substrate relative water content 5%-10%(severe stress),45%-50%(moderate stress)or 85%-90%(no stress,CK)],imposed for a duration of 15,30 or 45 days.The growth of S.tenuifolia showed increasing inhibition with increasing intensity of water deficit,with traits affected including the growth rate,leaf dry weight and total chlorophyll content,while leaf mass per area(LMA)increased under water deficit.Water deficit promoted the accumulation of osmotic adjustment substances in leaves,including soluble sugar,soluble protein,proline and Na^+.Water deficit also generally increased the antioxidant capacity of leaves:The activities of superoxide dismutase(SOD)and catalase(CAT)were moderately increased at 15 and 30 days,but decreased at 45 days,relative to CK,while peroxidase(POD)activity was moderately increased at 30 and 45 days.The contents of total phenol and total flavonoids were moderately increased at 15 days,and reached their highest levels under moderate drought at 30 and 45 days.Increased duration of water deficit affected the osmotic adjustment in leaves:The soluble sugar and soluble protein contents increased;the proline,K^+,Na^+and Ca^2+contents decreased;the activities of SOD and CAT increased initially and later decreased;POD activity continued to increase with time,and the accumulation of total phenols and total flavonoids increased initially and then remained unchanged.In summary,S.tenuifolia made adaptive responses to drought stress and showed tolerance to moderate drought.This study provides a theoretical basis for the standardized cultivation and water management of S.tenuifolia.