高温胁迫下花楸树幼苗的生理响应

Physiological Adaptation of Sorbus pohuashanensis Seedlings to Heat Stress

在40℃下对1年生花楸树幼苗进行0、2、4、68、1、0 h的高温胁迫,测定不同胁迫时间的叶绿素含量、相对电导率、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、抗坏血酸过氧化物酶(APX)活性、叶绿素荧光参数以及叶绿体超微结构等生理生化和形态指标。结果表明:高温胁迫下叶绿素含量下降,MDA含量增加,相对电导率增大,超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)含量先增加后降低;随着胁迫时间的延长,最大光量子产量(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qP)都呈下降趋势,非光化学淬灭系数(NPQ)呈上升趋势。高温胁迫0、6 h叶绿体超微结构基本没有发生变化,但是高温胁迫8 h,叶绿体超微结构发生了较大变化,质膜受到严重破坏,基粒片层变得模糊并且受到破坏,基质片层出现紊乱、排列错位等现象。

The chlorophyll fluorescence superoxide dismutase （SOD） activity, parameters, the contents of total chlorophyll and malondialdehyde （MDA）, ascorbate peroxidase （APX） activity and year-old Sorbus pohuashanensis seedlings stressed by high temperature （40℃ ） in chloroplast uhrastructure of onegrowth chamber were determined to elucidate its physiological response to heat stress. The results indicated that the contents of total chlorophyll decreased, electrolytic leakage and MDA increased, the activity of SOD and APX increased at first and then decreased with the increasing time of heat stress. The parameters of the largest quantum yield（ Fv/Fm）, actual photochemical efficiency（ΦPSⅡ ）, and photochemical quenching coefficient（qP）d-creased except for an increase of non-photo- chemical quenching coefficient（NPQ）. Chloroplast ultra-structure was serious damaged by 8 h heat stress, displa- ying collapsed chloroplast envelopes, blurred grana lamellae and disordered stroma lamellar. It is concluded that the seedlings of Sorbus pohuashanensis are sensitive to high temperature. It is proposed that the seedlings should be cul- tivated under partial shading at lower altitudes.