光和水分胁迫对臭柏实生幼苗光化学效率及色素组成的影响

为探明毛乌素沙地3年生臭柏(Sabina vulgaris)实生苗在不同光照和水分条件下的光抑制响应机制,研究了各处理臭柏实生苗的最大光化学效率(F_v/F_m)及叶绿素(Chla+Chlb)和叶黄素(A+V+Z)含量,分析了其叶绿素循环和叶黄素循环的变化规律。结果表明,77%透光区通过减少Chlb含量,升高Chla/Chlb,避免光能过剩;同时,增加A+V+Z及热散逸色素(A+Z)含量、提高(A+V+Z)/(Chla+Chlb)和(A+V)/(A+V+Z)值,耗散过剩光能,避免光破坏。25%透光区的叶绿素和叶黄素循环机制随着水分条件的变化迅速发生改变。10%透光区通过增加Chlb含量,降低Chla/Chlb,捕捉更多的光能,几乎不存在光抑制。毛乌素臭柏实生幼苗能够适应不同的光照和水分条件,在恶劣的沙漠中完成天然更新,形成独特的群落景观,与叶绿素循环和叶黄素循环有着密切的关系。

Effect of Light and Water Stress on Photochemical Efficiency and Pigment Composition of Sabina vulgaris Seedlings

We aimed to ascertain the photoinhibition response mechanism of 3-year-old Sabina vulgaris seedlings of Mu Us Sandland in different light and water conditions. We examined the photochemical efficiency of photosystem II at predawn (F_v/F_m) and the content of chlorophyll (Chla+Chlb) and lutein (A+V+Z) of every treatment and analyzed the change law of chlorophyll cycle and xanthophyll cycle. Sabina vulgaris seedlings avoided excess light energy and photodamage and dissipated excess light energy by decreasing the content of chlorophyllb (Chlb) and increasing the ratio of Chla to Chlb (Chla/Chlb ratio), content of A+V+Z and A+Z, (A+V+Z)/(Chla+Chlb) ratio and (A+V)/(A+V+Z) ratio in 77% light transmittance area. The mechanism of chlorophyll cycle and xanthophyll cycle of S. vulgaris seedlings was changed quickly with the change in water condition in 25% light transmittance area. S. vulgaris seedlings captured more light energy by increasing the content of Chlb and decreasing the Chla/Chlb ratio in 10% light transmittance area, with little photoinhibition in this area. S. vulgaris seedlings in Mu Us Sandland can adapt to different light and water conditions and can complete their natural regeneration as a unique community landscape in the harsh desert, which is closely related to chlorophyll cycle and xanthophyll cycle.