干旱胁迫下紫花苜蓿和黄花苜蓿实生苗叶片形态及解剖结构变化

Changes in Leaf Morphology and Anatomical Structure of Seedlings of Alfalfa and Medicago falcata L.under Drought Stress

通过分析不同的紫花苜蓿和黄花苜蓿材料,以期对干旱胁迫下的苜蓿叶片形态和组织解剖结构进行观察,旨在探究自然干旱胁迫下苜蓿幼苗叶片形态及解剖结构的适应性变化。以3个紫花苜蓿和2个黄花苜蓿为研究材料,分别设定4个不同的土壤相对含水量(土壤最大持水量的70%,55%,40%,25%)进行试验,处理30 d后测定叶片的形态结构和解剖结构。通过电镜观察紫花苜蓿和黄花苜蓿幼苗叶片形态和解剖结构,来探究苜蓿实生苗叶片对自然干旱胁迫的响应。结果表明,干旱胁迫会抑制苜蓿叶片的生长,随着干旱胁迫增强土壤水分降低,紫花苜蓿和黄花苜蓿的叶长、叶宽、叶面积降低,叶片厚度、叶肉厚度、下表皮厚度降低,栅栏组织厚度、海绵组织厚度下降,中脉中心厚度下降,栅海比呈现逐渐下降的趋势,叶片组织结构紧密度增加,疏松度减少,叶脉突起度增加。干旱胁迫强度与叶长、叶宽、叶面积、叶片厚度、叶肉厚度、下表皮厚度、栅栏组织厚度、海绵组织厚度、中脉中心厚度、栅海比、叶片组织结构疏松度呈负相关;与叶片组织结构紧密度、叶脉突起度呈正相关。

By analyzing different materials of Medicago sativa L.and Medicago falcata L.,this study aims to observe the leaf morphology and tissue anatomical structure of alfalfa under drought stress,and explore the adaptive changes in leaf morphology and anatomical structure of alfalfa seedlings under natural drought stress.This study used three alfalfa and two Medicago falcata L.as research materials,and set four different soil relative moisture contents(70%,55%,40%,and 25%of the maximum soil moisture capacity)for experiments.After 30 days of treatment,the morphological and anatomical structures of the leaves were determined.To investigate the response of alfalfa seedling leaves to natural drought stress by observing the leaf morphology and anatomical structure of purple and sickle alfalfa seedlings through electron microscopy.Drought stress would inhibit the growth of alfalfa leaves.With the increase of drought stress,the soil moisture decreased,the leaf length,leaf width,and leaf area of alfalfa and sickle alfalfa decreased,the thickness of upper epidermis increased,the thickness of leaf,mesophyll,and lower epidermis decreased,the thickness of palisade cell and sponge tissue decreased,the thickness of midrib center decreased,the palisade sea ratio gradually decreased,and the compactness of leaf tissue structure increased,the degree of looseness decreased and the degree of leaf vein protrusion increased.The intensity of drought stress was negatively correlated with leaf length,leaf width,leaf area,leaf thickness,mesophyll thickness,lower epidermis thickness,palisade cell thickness,sponge tissue thickness,midvein center thickness,palisade sea ratio,and leaf tissue structure porosity.It was positively correlated with the thickness of the upper epidermis,the tightness of leaf tissue structure,and the degree of leaf vein protrusion.