【作者】 代会平；

【导师】 向佐湘；

【作者基本信息】 湖南农业大学 ， 草业科学， 2008， 硕士

【摘要】 本研究针对当前国内护坡草本植物种类单一、生态适应性差、易退化等重要问题,从开发我国丰富野生植物资源着手,以湖南等地广泛分布、适应性强的野生狼尾草[Pennisetum alopecuroides（L.）Spreng]为研究对象,以常用护坡草种普通狗牙根[Cynodondactylon（L.）Pers]为对照,首次对野生狼尾草的茎叶水文生态效应、根系机械力学效应和抗旱性展开系统研究,以便为推广利用该植物开展边坡防护、植被恢复等生态工程实践提供科学的理论依据。主要研究结论如下:1、野生狼尾草茎叶水文生态效应总体上优于对照草种。野生狼尾草成坪时间49d,最大草层高度117.14cm,生长4个多月后茎叶鲜重112.93t/hm²、茎叶干重32.99t/hm²、茎叶最大截留率45.35%、茎叶最大截留量5.12mm,均明显优于对照草种;生长4个多月后枯落物有效蓄水率304.88%,略低于对照草种,但两者枯落物有效蓄水量均极低;野生狼尾草茎叶覆盖降低地表温度、保持土壤水分的生态效应比对照草种更显著。2、野生狼尾草根系机械力学效应明显强于对照草种。生长5个月后,野生狼尾草最大根深≥49.42cm,平均根粗1.05mm,0～50cm土层总根重7.72g/100cm²,根系平均最大抗拉力23.0N,根系平均抗拉强度40.18MPa,有效根密度54个/100cm²,土壤抗冲系数159.76L·s/g,根系减沙效应0.83,均明显大于对照草种。相同根径下野生狼尾草根系最大抗拉力和抗拉强度均明显高于对照草种;其根系最大抗拉力与根径成线性正相关,方程为F_r=26.56D-1.5225（R²=0.9805）;其根系抗拉强度与根径成指数负相关,方程为T_r=31.657D^-0.9227（R²=0.9672）。两草种根系明显增加了土体最大剪切力和最大剪位移,相同垂直压力下野生狼尾草土体抗剪强度显著大于对照草种;自然状态下（垂直压力10kPa）,野生狼尾草的土体抗剪强度为82.152kPa,根系强化土壤值为56.758kPa,均倍于对照草种;野生狼尾草的土体抗剪强度库仑公式为τ_f=σ·tan26.27°+77.216,φ=26.27°,c=77.216kPa;两草种根系主要是通过增加土壤粘聚力来增强土体抗剪强度。3、野生狼尾草抗旱性强于对照草种。干旱胁迫下,较之对照草种,野生狼尾草叶片相对电导率增幅小,质膜更稳定;叶片丙二醛（MDA）积累少,抗膜脂过氧化能力更强;叶绿素含量下降小,抗分解能力更强;叶片游离脯氨酸（Pro）积累慢,峰值高且出现时间晚,叶片可溶性糖含量高、增幅大,两者对野生狼尾草的渗透调节作用更持久有效。更多还原

【Abstract】 Aiming at the current important problems in herbaceous plant for slope protection,for example,the variety is unitary,the ecological adaptability is bad and so on,this research took exploitation of abundant wild plants resources in our country as the starting point,took wild Pennisetum alopecuroides[Pennisetum alopecuroides（L.） Spreng],which is widespread in Hunan province and has strong adaptability,as the object of study,and took Cynodon dactylon[Cynodon dactylon（L.） Pers],which is usually used in slope protection,as the contrast.Wild Pennisetum alopecuroides was systemly researched for the first time on the hydrological and ecological effect of stems and leaves,the mechanical effect of roots system and the drought resistance.In order to provide scientific theory basis for making use of this wild plant in ecological engineering practices,such as slope protection,vegetation recovering and so on.The main research results are as follows:1.The hydrological and ecological effect of stems and leaves of wild Pennisetum alopecuroides was overally better than Cynodon dactylon’s.The Formation time was 49d,the max.grass height was 117.14cm;after growth for more than 4 months,the fresh weight of stems and leaves was 112.93t/hm²,the dry weight was 32.99t/hm²,the max.interception rate and amount of stems and leaves were 45.35%and 5.12mm;wild Pennisetum alopecuroides was evidently better than Cynodon dactylon in these aspects.After growth for more than 4 months,the effective retaining-water rate of litter layer was 304.88%and less than Cynodon dactylon,but both of the effective retaining-water amounts were very low.Stems and leaves of wild Pennisetum alopecuroides can reduce ground temperature and maintain soil water more evidently and effectivly than Cynodon dactylon’s.2.The mechanical effect of roots system of wild Pennisetum alopecuroides was evidently stronger than Cynodon dactylon’s.After growth for 5 months,the deepest root was more than 49.42cm,the average roots diameter was 1.05mm,the roots weight was 7.72g/100cm² in 0～50cm soil,the average roots max.tensile stress was 23.0N,the average roots tensile strength was 40.18MPa,the effective roots density was 54/100cm²,the soil Anti-scouribility coefficient was 159.76L·s/g,the roots effect on reducing sand was 0.83,wild Pennisetum alopecuroides was evidently more than Cynodon dactylon in these aspects.The roots max. tensile stress and tensile strength of wild Pennisetum alopecuroides were greater than Cynodon dactylon’s with the same diameter;the relation between roots max.tensile stress and roots diameter was linear and positive,the formula was F_r=26.56D-1.5225（R²=0.9805）; the relation between roots tensile strength and roots diameter was linear and negative,the formula was T_r=31.657D^-0.9227（R²=0.9672）.Roots of two grasses evidently increased the max.shear stress and the max.shear displacement of soil,the soil shear strength of wild Pennisetum alopecuroides was evidently greater than Cynodon dactylon’s under the same vertical stress;the soil shear strength and the roots strengthening value of wild Pennisetum alopecuroides,which were far more than Cynodon dactylon’s,were 82.152kPa and 56.758kPa in natural conditions（the vertical stress was 10kPa）;the Coulomb formula for soil shear strength of wild Pennisetum alopecuroides wasτ_f=σ·tan26.27°+77.216,φ=26.27°,c =77.216kPa;Roots of two grasses strengthened soil shear strength mainly because they increased the soil cohesion.3.The drought resistance of wild Pennisetum alopecuroides was stronger than Cynodon dactylon’s.Compared with Cynodon dactylon,the leaves relative conductivity of wild Pennisetum alopecuroides was increased less,the plasma membrane was stabler;the leaves MDA content was accumulated less,the peroxidation resistance of membrane and fat was stronger;the Chlorophyl content was decreased less,the Chlorophyl dissolution resistance was stronger;the leaves Pro content was accumulated more slowly,the peak value of leaves Pro content,which appeared later,was higher,the leaves soluble sugar content was higher, and increasing range was greater,the osmotic adjustment of Pro and soluble sugar in wild Pennisetum alopecuroides was more lasting and effective.更多还原