辽东栎幼苗生长和生理特性对光照强度的响应

Responses of growth and physiological characteristics of Quercus wutaishanica seedlings to the light intensity

【目的】光照强度对森林树种的幼苗生长与存活及种群更新都具有重要影响。研究光照强度对幼苗生长和生理特性的影响可为退化次生林的人工辅助实生更新提供科学依据。【方法】将盆栽辽东栎幼苗自5.3%自然全光照(NS)分别转移至16.0%NS、37.2%NS和100%NS下,研究幼苗生长及生理特性及其形态学可塑性对光照强度变化的响应。【结果】幼苗株高、基径、叶片数、单株叶面积、主根长、总干质量和根冠比均随光照增强先增大后减小,且均在37.2%NS处理(株高、基径、叶片数、单株叶面积、总干质量和根冠比)或16.0%NS处理(主根长)最大,其中基径、叶片数、单株叶面积和主根长在16.0%NS和37.2%NS处理均显著大于对照,总干质量在3个高光强下均显著大于对照。幼苗根冠比在37.2%NS处理显著大于100%NS处理22.0%,比叶面积随光照增强逐渐减小;相对生长率和净同化率在37.2%NS和16.0%NS处理均约为对照的8倍以上。幼苗叶片SOD、POD、CAT活性和MDA含量均随光强提高逐渐降低,在100%NS下所有酶活性和MDA含量均显著低于对照;叶片可溶性蛋白、游离脯氨酸含量和叶绿素总量随着光强提高呈降低趋势,在37.3%NS和100%NS处理均显著低于对照。【结论】辽东栎幼苗生长和生理能够对光强变化做出快速响应,并表现出较大的形态和生理可塑性,营造适当大小的林窗改善林下光照条件状况可能有助于幼苗生长和次生林更新。

【Objective】Light intensity is of great importance for the growth and survival of seedling and population regeneration of tree species.The investigation on the effects of light intensity on the seedling growth and physiological characteristics can provide scientific basis for the artificial supplementary seedling regeneration of degraded secondary forest.【Method】Quercus wutaishanica seedlings planted in pot were transfered from 5.3%natural sunlight(NS)(control)to 16.0%NS,37.2%NS and 100%NS,respectively,to investigate the responses of growth and physiological characteristics of seedlings to the light intensity.【Result】Shoot height(SH),basal stem diameter(BSD),leaf number(LN),leaf area per plant(LAPP),taproot length(TRL),total dry mass(TDM),and root-shoot ratio(RSR)of Q.wutaishanica seedlings all increased at first and then declined.Maximums of all above parameters were observed under either 37.2%NS(SH,BSD,LN,LAPP,TDM,and RSR)or 16.0%NS treatment(TRL).The BSDs,LNs,LAPPs,and TRLs of seedlings grown under 16.0%NS and 37.2%NS were all significantly higher than those of control seedlings.Also,seedlings grown under three higher light intensity all had high TDMs which were significantly higher than that of control seedlings.Root-shoot ratio of seedlings grown under 37.2%NS was 22.0%higher significantly than that of seedlings grown under 100%NS,while specific leaf area declined with the light intensity enhancing.The relative growth rate and net assimilation rate of seedlings grown under 37.2%NS and 16.0%NS were approximately eight times higher than that of control seedlings.Leaf activities of SOD,POD and CAT and content of MDA declined with the light intensity increasing,and the activities of three anti-oxidative enzymes and content of MDA of seedlings grown under 100%NS were all significantly lower than those of control seedlings.The contents of leaf soluble protein,free proline,and total chlorophyll all presented a decreasing tendency with the light intensity increasing,and significantly lower levels of them were detected in seedlings grown under 37.3%NS and 100%NS than in control seedlings.【Conclusion】The growth and physiology of Q.wutaishanica seedlings can respond rapidly to light intensity and show a high morphological and physiological plasticity,suggesting that creation of moderate-sized forest gap to perfect light condition under forest canopy would benefit seedling growth and regeneration of secondary Q.wutaishanica forest.