沙化草地三种牧草叶片生理适应特性的比较研究

A comparative study on the physiological adaptation characteristics of three kinds of forage leaves in sandy grassland

为了探究高寒沙化草地不同牧草叶片的生理适应特性,选取该地种植的优势牧草以礼草(Koegneria hirsute)、赖草(Leymus secalinus)和垂穗披碱草(Elymus nutans)为研究材料,通过测定其叶片光合特性、光响应曲线、生理酶活性、渗透调节物质含量,比较三种牧草叶片生理特性指标,分析了同时间点的叶片光合特性和叶片活性酶的相关关系,结果表明:1)以礼草和赖草的叶片具有较强的光合特性,其中以礼草具有较高的光饱和点(LSP)和最大光合速率(Pnmax),对光的适应范围最广,是其能适应这种生境的主要生理特性之一;垂穗披碱草通过改变叶片的内外蒸气压,加快蒸腾速率来适应沙化逆境。三种牧草的净光合速率最大值为:以礼草>赖草>垂穗披碱草。2)以礼草叶片的丙二醛(MDA)含量低于赖草和垂穗披碱草(P<0.01),以礼草叶片的抗坏血酸过氧化物酶(APX)活性显著高于赖草和垂穗披碱草(P<0.05),赖草叶片的过氧化物酶(POD)活性显著高于以礼草和垂穗披碱草(P<0.05),叶片生理指标综合评判看出,三种牧草中以礼草的适应性最强。3)超氧化物歧化酶(SOD)活性显著影响三种牧草叶片的LSP和光的补偿点(LCP)(P<0.05)。

To explore physiological adaptability characteristic about the leaves of forage in Alpine sandy grassland,we choose the Koegneria hirsute,Leymus secalinus,Elymus nutans to do the research,which through measure the leaf of photosynthetic characteristics,light response curves,biological enzymes,osmoregulation substances,comparing the leaf physiological characteristics index,analysis of the relation between leaf photosynthetic characteristics and leaf active enzyme of three kinds of forage grass on sandy grassland.The results indicate that:1)Desertification habitat,the leaves of pioneer grass have stronger photosynthetic characteristics,especially,the K.hirsute has the widely light adaption range,including the LSP and Pnmax is important physiological character improving the habitat,E.nutans can adapt to the desertification habitat by changing the internal and external vapor pressure of leaves and accelerating transpiration rate.The Pnmax of the three forages was K.hirsute>L.secalinus>E.nutans.2)The MDA content in the leaves of K.hirsute was lower than L.secalinus and E.nutans(P<0.01),the APX in the leaves of K.hirsute is height than L.secalinus and E.nutans(P<0.05).the POD in the leaves of L.secalinus is height than K.hirsute and E.nutans(P<0.05).It can be seen that K.hirsute leaves is stronger adaptability in the desertification grassland.3)SOD enzyme activity had the significance effect on the LSP and LCP of the forage leaves(P<0.05).