【作者】 陈苗；

【导师】 郑炳松； 黄坚钦；

【作者基本信息】 浙江农林大学 ， 森林培育， 2010， 硕士

【摘要】 钾是植物必需的大量元素,在各种生理生化过程中起着重要作用。为了研究山核桃幼苗对缺钾响应的生理生化机制,本研究通过测定光合特性(气体交换、叶绿素荧光参数、叶片的能量分配、电子流分配的变化)、抗氧化酶指标、色素含量、可溶性蛋白含量、营养元素含量、碳水化合物含量等生理生化指标,并且结合反射光谱的测定结果进行了分析,结果如下:1.在缺钾条件下,山核桃幼苗的Pn、Gs随着处理时间的延长而下降,而Ci则先下降后上升;同时光合色素、可溶性蛋白含量降低。进一步的叶绿素荧光特性研究表明,随着钾胁迫时间的延长,缺钾山核桃叶片中的Fv/Fm、F′v/F′m、ФPSⅡ、qP及ETR均大幅度降低,说明PSⅡ反应中心受到伤害。缺钾叶片NPQ显著上升,说明钾胁迫下的山核桃叶片通过启动热耗散机制耗散过剩的激发能,以减轻因PSⅡ吸收过多光能而引起的光抑制和光氧化,从而保护光合机构免受伤害。缺钾叶片Prate显著下降,Drate上升,这说明缺钾使山核桃叶片受到明显的光抑制。高Jo/Jf表明山核桃是高光呼吸的物种,但山核桃没有启动光呼吸防御系统以适应缺钾胁迫。缺钾诱导山核桃细胞内活性氧增加,诱导抗氧化酶SOD活性上升,POD、CAT活性降低,膜脂过氧化加剧,MDA升高。2.缺钾引起山核桃的各种营养元素含量发生改变。缺钾促进了山核桃根茎叶对P的吸收,降低了山核桃根茎叶对K、Fe的吸收,降低了山核桃叶对N的吸收,促进了山核桃根叶对Mg的吸收,降低了茎中Mg的含量,促进了山核桃叶对Ca、Zn和Mn的吸收,降低了根茎中Ca和Mn的含量。缺钾处理导致山核桃叶片中可溶性糖、蔗糖及淀粉的含量均显著下降,而还原糖和果糖含量在叶片中增加。缺钾引起各营养元素和碳水化合物在山核桃幼苗中的含量变化机制有待于进一步研究。3.缺钾使山核桃叶片反射率在可见光区(500-710nm)和近红外波段升高;钾素的补充使红边位置红移,红边幅值减小;GNDVI、PSNDa、PSNDb、PRI、mSR705、mND705、R800/R700、R800/R640随着钾素的补充而显著增加;Rch随着钾素的补充而显著降低;但NVDI、PSSRa、PSSRb、PSSRc、PSNDc、NPCI、SIPI、(R678-R486)/R800、R800(1/R520-1/R700)在缺钾处理植株和对照组间没有什么显著的变化。山核桃叶片光谱参数NVDI、PSSRa、PSSRb、PSSRc、PSNDc、SIPI、R800(1/R520-1/R700)、(R678-R486)/R800和叶绿素a、叶绿素b、类胡萝卜素、叶绿素a/b、类胡萝卜素/叶绿素、叶片全钾含量之间相关性都很小,均没有达到显著水平(P>0.05)。而GNDVI、Rch、PSNDa、PSNDb、NPCI、mSR705、mND705、R800/R700、R800/R640、Sred与所有色素指标和全钾之间的相关性均达到显著水平。更多还原

【Abstract】 Potessium is one of the essential macronutrients in plant and plays a vital role in various physiological and biochemical process. To investigate the physiological and biochemical mechanism of hickory (Carya carthcryerisis) seedling under potessium deficiency, the photosynthetic characteristics (including gas exchange parameters, fluorescence parameters, Drate, Jf and so on), antioxidant enzymes activities, photosynthetic pigments, soluble protein, essential nutrients, carbohydrate and reflection spectrum were studied. The results are summarized as follows:1. The net photosynthetic rate(Pn), stomatal conductance(Gs), pigments and soluble protein decreased significantly, while intercellular CO2 concentration(Ci) decreased at first, and then increased, from the beginning to the 60th day after potassium deficiency treatment in the hickory seedling. The further study on chlorophyll fluorescence measurement showed that maximal photochemistry of PSⅡ(Fv/Fm)、excitation energy capture efficiency of open PSⅡ(F′v/F′m)、ФPSⅡ(Effective quantum yield of FSII)、qP (Photochemical quenching) and ETR (Electron transport rate through PSII) were declined under potassium deficiency, indicating that the PS II reaction center was damaged. We also detected a significant increase of NPQ ( Non photo-chemical quenching) in the stressed leaves of hickory, which indicated that the mechanism of thermal dissipation had been started to dissipate excess light energy, and protect the plants from photo-inhibition and photo-oxidation. Prate decreased, Drate increased, significantly , indicating that a remarkable photoinhibition of photosynthesis existed in the stressed leaves of hickory. A high Jo/Jf indicated hickory was a high photorespiration plant, but hickory did not promote photorespiration to adapt to potassium deficiency stress. Potassium deficiency caused hickory to increase the reactive oxygen. The activity of SOD (Superoxide dismutase) increased and the activities of POD(Peroxidase) and CAT(Catalase) were declined under potessium deficiency. Potassium deficiency accelerated the membrance liquid peroxidation and increased the content of MDA.2. Potassium deficiency resulted in the increase of the content of P in the root, stem and leaf, Mg in the root and leaf, Ca, Zn and Mn in the leaf and the decrease of K and Fe in the root, stem and leaf,N in the leaf, Mg in the stem, Ca and Mn in the root and stem of hickory. The content of soluble sugar, sucrose and total starch decreased, while the content of sugar and fructose increased under potessium deficiency. The change mechanisms of various essential nutrients and carbohydrates in hickory caused by potassium deficiency needs further investigations.3. Potassium deficiency caused leaf reflection spectrum in the visible region (500~710nm) and near infrared bands increased. Potassium supplement shifted the red edge position to red band, narrowed the red edge range. GNDVI, PSNDa, PSNDb, PRI, mSR705, mND705, R800/R700 and R800/R640 increased while Rch decreased significantly with potassium supplement. However, NVDI, PSSRa, PSSRb, PSSRc, PSNDc, NPCI, SIPI, (R678-R486)/R800, R800(1/R520-1/R700) did not show significant differences. There were no correlation between NVDI, PSSRa, PSSRb, PSSRc, PSNDc, SIPI, R800(1/R520-1/R700), (R678-R486)/R800, pigments and potassium contents. However, there were significent correlation between GNDVI, Rch, PSNDa, PSNDb, NPCI, mSR705, mND705, R800/R700, R800/R640, Sred, pigments and potassium contents.更多还原