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干旱胁迫对喀斯特生境蚬木幼苗光合特性及抗性生理的影响

欧芷阳*,曹艳云,谭长强,郑威,庞世龙,申文辉   

  1. (广西壮族自治区林业科学研究院, 南宁 530002)
  • 出版日期:2018-11-10 发布日期:2018-11-10

Effects of drought on photosynthesis and resistance physiology of Excentrodendron hsienmu seedlings in karst habitat.

OU Zhi-yang*, CAO Yan-yun, TAN Zhang-qiang, ZHENG Wei, PANG Shi-long, SHEN Wen-hui   

  1. (Guangxi Forestry Research Institute, Nanning 530002, China).
  • Online:2018-11-10 Published:2018-11-10

摘要: 为了解蚬木(Excentrodendron hsienmu)幼苗对喀斯特干旱生境的生理适应,基于构建的模拟喀斯特生境装置,以2年生蚬木幼苗为供试材料,研究岩溶水分和土壤水分两个因素对蚬木幼苗叶片光合及抗性生理的影响。结果表明:蚬木的光合作用-光响应曲线符合非直角双曲线函数模型,岩溶水层2种处理下的光响应曲线变化基本一致。土壤水分显著影响叶片最大净光合速率和暗呼吸速率,2个因素及其交互作用极显著影响叶片相对叶绿素含量。最大净光合速率和暗呼吸速率随土壤干旱胁迫加剧而下降,相对叶绿素含量则表现为增加趋势。土壤水分极显著影响游离脯氨酸、显著影响丙二醛和过氧化物酶,干旱胁迫组的游离脯氨酸含量显著高于对照,重度干旱胁迫下丙二醛含量显著高于对照。过氧化物酶活性均随干旱加剧先升后降,峰值出现在中度胁迫。研究表明,蚬木具有较强的耐旱潜力,渗透调节物质的主动适应是其耐旱的主要原因。

关键词: 火干扰, 叶片功能性状, 兴安落叶松群落, 物种多样性, 功能多样性

Abstract: To understand the physiological adaptability of Excentrodendron hsienmu to arid habitat of karst mountains, a moisture control experiment was conducted with 2-year-old E. hsienmu seedlings in a water supply device, which was set up with a simulated karst structure comprising soil, limestone, and epikarst layer. A twofactor design, soil layer and epikarst layer water gradient condition, was performed to examine leaf photosynthetic and resistance physiological characteristics of E. hsienmu seedlings. The results showed that the photosynthesislight response curve of the seedlings well fitted the nonrectangular hyperbola model. Light response curve under different treatments in epikarst layer showed the similar variation. Results of twoway analysis of variance showed soil layer water significantly affected the maximum net photosynthetic rate (Pmax) and dark respiration rate. Both factors and their interaction had markedly significant effects on relative chlorophyll value. The Pmax and dark respiration rate decreased, while relative chlorophyll value increased with the increases of soil drought stress. Soil layer water very significantly affected free proline, and had significant impact on both malondialdehyde content (MDA) and peroxidase (POD) activity. Content of free proline in drought stress groups was significantly higher than that in control, while MDA content under severe drought stress was significantly higher than that in control. Peroxidase activity increased firstly, and then decreased with the increases of soil drought stress, with the peak occurring in moderate drought stress. Our results demonstrate that E. hsienmu has strong tolerance to drought stress, with the active adaptation of osmotic adjustment as the main reason.

Key words: fire disturbance, leaf functional trait, Larix gmelinii community, species diversity, functional diversity