植物生态学报 ›› 2012, Vol. 36 ›› Issue (7): 662-670.doi: 10.3724/SP.J.1258.2012.00662

• 研究论文 • 上一篇    下一篇

田间条件下棉花幼叶光合特性及光保护机制

李维, 张亚黎, 胡渊渊, 杨美森, 吴洁, 张旺锋*   

  1. 石河子大学农学院/新疆生产建设兵团绿洲生态农业重点实验室, 新疆石河子 832003
  • 收稿日期:2011-12-29 修回日期:2012-04-10 出版日期:2012-07-01 发布日期:2012-07-10
  • 通讯作者: 张旺锋 E-mail:zwf_shzu@163.com
  • 基金资助:

    国家自然科学基金项目、国家科技支撑计划项目

Research on the photoprotection and photosynthesis characteristics of young cotton leaves under field conditions

LI Wei, ZHANG Ya-Li, HU Yuan-Yuan, YANG Mei-Sen, WU Jie, and ZHANG Wang-Feng*   

  1. Key Laboratory of Oasis Ecol-agriculture of Xinjiang Production and Construction Crop, College of Agricultural, Shihezi University, Shihezi, Xinjiang 832003, China
  • Received:2011-12-29 Revised:2012-04-10 Online:2012-07-01 Published:2012-07-10
  • Contact: ZHANG Wang-Feng E-mail:zwf_shzu@163.com

摘要:

通过比较棉花(Gossypium hirsutum)幼叶和完全展开叶气体交换参数及叶绿素荧光特性的差异, 探讨高光强下幼叶的光抑制程度及明确光保护机制间的协调机理。在田间自然条件下, 以棉花刚展平的幼嫩叶片(幼叶)和面积已达到最大的完全展开叶片为研究对象, 通过测定不同发育阶段叶片气体交换参数及叶绿素a荧光参数的变化, 并运用Dual-PAM100对不同发育阶段的叶片进行快速光响应曲线的拟合。结果表明: 幼叶和完全展开叶片在光合、荧光特性方面表现出明显的差异。与完全展开叶相比, 较低的叶绿素(Chl)含量和气孔导度(Gs)是幼叶较低净光合速率(Pn)的限制因素, 从而直接导致其光系统II(PSII)实际光化学效率(ΦPSII)和光化学猝灭系数(qP)的降低。在1 800 μmol·m–2·s–1光强以下, 完全展开叶具有较强的围绕PSI循环的电子流(CEF), 有利于合成ATP, 是其具有较高光合能力的原因之一。相同光强下, 幼叶较低的光饱和点(LSP)更易受光抑制, 但其PSII原初光化学效率(Fv/Fm)的日变化幅度显著小于完全展开叶, 说明强光下幼叶通过类胡萝卜素(Car)猝灭单线态氧、光呼吸(Pr)、热耗散(NPQ)以及PSI-CEF等光保护机制能有效地耗散过剩的光能, 从而避免其光合机构发生光抑制。

Abstract:
Aims Differences of photosynthesis and chlorophyll fluorescence characteristics between flat young leaves (young leaves) and fully grown leaves (mature leaves) of cotton were compared to study the adaptation mechanisms of photoinhibition and photoprotection on young leaves under strong sunlight.
Methods We measured gas-exchange and chlorophyll fluorescence of young and mature leaves of cotton under field conditions and obtained rapid light curves with a Dual-PAM100 using an internal program.
Important findings There were significant differences between young and mature leaves in photosynthesis and fluorescence characteristics. Young leaves had lower chlorophyll content (Chl) and stomatal conductance (Gs), which accounted for lower net photosynthetic rate (Pn), which in turn resulted in lower actual photochemical efficiency (ΦPSII) and photochemical quenching (qP) in photosystem II (PSII). Below 1 800 μmol·m–2·s–1, the higher cyclic electron flow (CEF) that was useful for composing ATP is one of the reasons for higher photosynthetic capacity in mature leaves. Lower light saturation point (LSP) was more susceptible to photoinhibition in young leaves under the same light; however, the magnitude of diurnal variation of its maximum photochemical efficiency of PSII (Fv/Fm) was significantly less than that of mature leaves. We suggest that photoprotective mechanisms, including direct quenching of reactive oxygen species by abundant carotenoids, photorespiration (Pr), non-photochemical quenching (NPQ) and the cyclic electron flow around PSI (PSI-CEF), can effectively dissipate the excess energy in young leaves to avoid photoinhibition under high irradiance.