干旱胁迫对紫花苜蓿叶片衰老的影响

发布时间：2018-01-09 13:22

  本文关键词：干旱胁迫对紫花苜蓿叶片衰老的影响　出处：《仲恺农业工程学院》2017年硕士论文　论文类型：学位论文

  更多相关文章： 干旱胁迫 紫花苜蓿 叶片衰老

【摘要】：紫花苜蓿是优良的豆科牧草,因其具有养护容易、抗逆性强、花期长等优点,可作为园林景观地被植物及生态果园和茶园的护坡植物在南方地区开发和利用,但南方地区季节性干旱会限制紫花苜蓿的推广与利用。干旱胁迫会导致紫花苜蓿叶片衰老,影响景观效果。本研究以两种抗旱性差异较大的紫花苜蓿为试验材料,采用温室盆栽方式,对在干旱胁迫下紫花苜蓿叶绿素含量、叶片衰老率、叶片相对含水量、光合作用、叶绿素荧光参数等叶片衰老特征指标进行测定,评价了抗旱性强弱不同的紫花苜蓿在干旱胁迫下其叶片衰老特征的差异,同时研究了6-BA(6-苄氨基嘌呤)对延缓紫花苜蓿叶片衰老的作用,研究结果为紫花苜蓿作为景观植物加以推广提供了依据。主要研究结果如下:(1)干旱胁迫下紫花苜蓿叶片相对含水量(RWC)下降,水分饱和亏缺(WSD)上升。与抗旱性差的WL-712苜蓿相比,抗旱性强的陇东苜蓿叶片RWC下降幅度及WSD上升幅度均较小,复水后叶片RWC恢复程度高。(2)干旱胁迫下两种紫花苜蓿叶绿素a、叶绿素b及叶绿素(a+b)含量均下降,叶绿素a/b呈上升趋势。抗旱性强的陇东苜蓿叶绿素(a+b)含量降解幅度低,抗衰老能力强。(3)干旱胁迫下紫花苜蓿叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间二氧化碳浓度(Ci)降低,气孔限制值(Ls)升高。与WL-712相比,抗旱性强的陇东苜蓿Pn、Tr、Gs、Ci降幅小,Ls升高幅度低,提高了植株的抗旱能力。(4)干旱胁迫下紫花苜蓿叶片PSⅡ潜在活性(Fv/Fo)和PSⅡ反应中心光化学效率(Fv/Fm)降低。抗旱性强的陇东苜蓿其Fv/Fo、Fv/Fm较抗旱性差的WL-712下降幅度低,复水后恢复程度高,具有较强的光合适应能力。(5)干旱胁迫造成紫花苜蓿叶片衰老率增加,抗旱性强的陇东苜蓿叶片衰老率低。(6)叶片表面喷施6-BA能显著提高干旱胁迫下紫花苜蓿叶片RWC,降低叶片WSD,提高叶片的保水能力。(7)叶片喷施6-BA能降低干旱胁迫对紫花苜蓿叶片细胞膜的伤害。与未喷施6-BA的干旱处理相比,喷施6-BA能降低紫花苜蓿叶片相对电导率的上升幅度。(8)叶片喷施6-BA可提高干旱胁迫下紫花苜蓿叶片叶绿素a含量及叶绿素(a+b)含量,复水后叶绿素a、叶绿素(a+b)含量接近对照或高于对照,有效缓解干旱胁迫对光合色素的降解作用。(9)干旱胁迫下,喷施6-BA的紫花苜蓿叶片衰老率低,对比抗旱性弱的WL-712,抗旱性强的陇东苜蓿叶片衰老率的降幅较大。
[Abstract]:Alfalfa is an excellent legume forage, because of its easy maintenance, strong resistance, long flowering period and other advantages, it can be used as landscape cover plants, ecological orchards and tea garden slope plants in the southern region development and utilization. But seasonal drought in southern China will limit the spread and utilization of alfalfa. Drought stress will lead to alfalfa leaf senescence. In this study, two alfalfa varieties with different drought resistance were used as experimental materials and greenhouse pot culture was used to study the chlorophyll content and leaf senescence rate of alfalfa under drought stress. Leaf senescence characteristics such as relative water content, photosynthesis and chlorophyll fluorescence parameters were measured to evaluate the difference of leaf senescence characteristics of alfalfa with different drought resistance. At the same time, the effect of 6-BA 6-benzyl aminopurine on delaying the senescence of alfalfa leaves was studied. The results provided a basis for the application of alfalfa as landscape plants. The main results were as follows: 1) the relative water content of alfalfa leaves decreased under drought stress. Compared with the WL-712 alfalfa with poor drought resistance, the leaf RWC and WSD of the drought-resistant alfalfa were smaller than those of the drought-resistant alfalfa. The content of chlorophyll a, chlorophyll b and chlorophyll a b of two kinds of alfalfa decreased under drought stress. Chlorophyll a / b showed an upward trend. The content of chlorophyll a b) in Longdong alfalfa with strong drought resistance was low, and its ability to resist senescence was strong. 3) under drought stress, the net photosynthetic rate (PN) of alfalfa leaves was higher than that of alfalfa. Stomatal conductance, transpiration rate and intercellular carbon dioxide concentration were decreased and stomatal limiting value was increased. Compared with WL-712, the drought-resistant alfalfa in east Gansu Province had higher Tr. The decrease of GsCi was small and the increase of GsCi was low. Under drought stress, the photochemical efficiency of PS 鈪，

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