中文摘要：

捕光色素分子的内禀特性不仅决定了光能的吸收与传递，也将影响到激发能向光化学反应、热耗散和叶绿素荧光的分配。本文采用叶绿素荧光技术和光合电子流对光响应机理模型，研究了越冬期广玉兰（Magnolia grandiflora）阳生叶和阴生叶两种不同光环境下叶片PSⅡ功能及其捕光色素分子内禀特性的差异，以探索广玉兰越冬的光保护策略。结果表明：越冬期低温导致叶片轻微光抑制的发生，全光照加剧了阳生叶光抑制程度，而弱光环境有利于阴生叶光抑制的恢复。阳生叶可通过降低叶绿素含量和捕光色素分子数量以减少对光能的吸收，并且具有较强的光化学和热耗散能力以保护光合机构免受低温强光伤害。而阴生叶虽然其光化学反应能力相对较弱，但具有较强的热耗散能力，可有效地保护其免受短时曝露在强光下的伤害。

英文摘要：

Light absorption and energy transfer are determined by intrinsic characteristics of light-harvesting pigment molecules, which also have impacts on distribution of excited energy for photochemical reaction, heat dissipation and chlorophyll fluorescence. We compared the differences of the PS 11 function and intrinsic characteristics of light-harvesting pigment molecules of sun- and shading-leaves to study the strategies in overwintering Magnolia grandiflora. The slight photoinhibition was caused in photoprotective leaves of M. grandiflora by low temperature during overwintering. Natural sunlight enhanced photoinhibition in sunleaf, however, low light condition was propitious to the recovery of photoinhibition in shading-leaf. Sun-leaf had lower chlorophyll content and the numbers of light-harvesting pigment molecules （NO ） to reduce light energy absorption. Sun-leaf also possessed higher photochemical function and thermal energy dissipation in PS Ⅱ, which would protect photosynthetic apparatus against damage by low temperature and high light. Shading-leaf exhibited lower capability of photochemical reaction, however, possessed greater thermal energy dissipation, which would alleviate photoinhibition of shadingleaf under temporal high light condition during overwintering.