水分胁迫及遮光处理对沙漠植物约书亚树(Yucca brevifolia)幼苗光合特性的影响  

Effects of Water Stress and Shading on Photosynthetic Characteristics of Yucca brevifolia Seedlings

作　　者：刘力宁[1] 满秀玲[1] 唐中华[1] 李奕[1] 

机构地区：[1]东北林业大学林学院,黑龙江哈尔滨150040

出　　处：《中国沙漠》2013年第3期758-764,共7页Journal of Desert Research

基　　金：国家林业局引进国际先进林业科学技术项目(2009-4-18)资助

摘　　要：以3年生约书亚树(Yucca brevifolia)幼苗为试材,选择不同水分胁迫(相对含水量≥75%(正常)、50%～60%(中度)和35%～45%(重度))及不同遮光处理(自然光、60%透光和20%透光)进行试验,对幼苗光合特性指标及叶绿素相对含量值(SPAD)进行研究。结果表明:(1)随着水分胁迫的加剧,约书亚树幼苗净光合速率(Pn)、气孔导度(Gs)、水分利用效率(WUE)明显下降,但自然光下重度水分胁迫幼苗WUE值远高于其他处理。幼苗光饱和点(LSP)均表现为重度水分胁迫>正常供水>中度水分胁迫。(2)水分胁迫下,60%透光率处理的幼苗叶宽增加,Pn、蒸腾速率(Tr)及Gs明显提高,而20%透光率下幼苗各指标均显著降低。(3)相同光照条件下,随着水分胁迫的加剧,幼苗SPAD值明显下降;相同水分条件下,随着透光率的减小,幼苗SPAD值增大。因此,在约书亚树幼苗培育时,应适当增加水分胁迫以提高幼苗的水分利用效率及光饱和点,同时,适当的遮光环境(透光率在60%左右)也可提高幼苗的光合能力及SPAD值,确保约书亚树幼苗生长及在我国沙漠地区引种成功。Triennial seedlings were selected as objects to study the photosynthetic characteristic index and SPAD value of Yucca brevifolia seedling under different water stress （Normal, RWC≥75%; Moderate, RWC50 % -- 60 % ; Severe, RWC35 % -- 45 % ） and different shading treatments （natural light, 60 % natural light, 20% natural light）. The results showed that： （1） With the intensifying of water stress, the net photosynthetic rate （Pn）, stomatal conductance （Gs） and water use efficiency （WUE） declined obviously. But, under severe water stress and natural light condition, the WUE was much higher than that under other treatments. The light saturation point （LSP） ranked as severe water stress〉normal〉moderate. （2） Under water stress, the blade width of seedlings increased, Pn, transpiration rate （Tr） and Gs of seedlings increased obviously on 60% natural light condition, while all index of seedlings declined significantly under 20% natural light. （3） On the same light condition, SPAD value of seedlings declined obviously as water stress intensified; under the same moisture condition, SPAD value rose as luminousness decreased. There- fore, when producing Yucca brevifolia seedlings, water stress should be increased properly to enhance WUE and LSP of seedlings. At the same time, a proper shading environment （around 60% natural light） could increase photosynthetic ability and SPAD value of seedlings, which can guarantee the growth and successful introduction of Yucca brevifolia seedlings in the desert area.

关 键 词：水分胁迫 遮光 约书亚树(Yucca brevifolia) 光合特性 SPAD值 

分 类 号：S718.43[农业科学—林学]