岩溶石漠化区四种牧草植物光合生理适应性特征

The photosynthetic characteristics of four forage grasses in Karst rock desertification areas

以类玉米、紫花苜蓿、菊苣和杂交狼尾草4种牧草植物为研究对象,通过测定其叶片结构性状、光合生理特征以及土壤理化特性,研究其对岩溶石漠化环境的生理适应性的差异。结果表明,4种牧草植物的叶面积(LA)、叶干重(DW)、叶绿素含量(Chl)和比叶面积(SLA)差异显著,反映出4种牧草植物叶片结构性状差异种间较大;同科植物类玉米和杂交狼尾草光合能力相近,而不同科植物如菊苣和紫花苜蓿光合能力差异较大,但其水分利用效率(WUE)和潜在水分利用效率(WUEi)相近;相比较而言,类玉米和杂交狼尾草具有较强的光合能力和较高的水分利用效率,而菊苣和紫花苜蓿的光合能力和水分利用效率相对较低。4种牧草对0～10和10～20cm土层土壤含水量的影响差异不大,但对土壤容重的影响存在差异。相关分析表明,4种牧草植物蒸腾速率(Tr)与0～10cm土层土壤含水量为显著的正相关关系,而10～20cm土层土壤含水量对大气饱和蒸汽压亏缺(Vpdl)影响较大。相比较而言,类玉米和杂交狼尾草具有较高的Pn,WUE和WUEi,对岩溶环境具有良好的适应性。

The photosynthetic and leaf traits of four grasses （Zea diploperennis,Medicago sativa,Cichorium intybus,and Pennisetum americanum×Purpureum） were studied in field conditions,together with soil water content and soil bulk density to clarify their physiological adaptability to the Karst rocky desertification environment.There were significant differences of leaf area （LA）,dry matter（DW）,Chl,specific leaf area （SLA） among these four forage grasses.Zea diploperennis had the greatest LA and DW,while M.sativa had the lowest.SLA was in the sequence C.intybusM.sativaZ.diploperennisP.americanum×Purpureum.M.sativa had the most Chl but there were no obvious differences of Chl between the other three forage grasses,indicating the great differences of the leaf structural traits among these four forage grasses.Z.diploperennis and P.americanum×Purpureum had high Pn,but low Tr and gs and therefore large WUE and WUEi,but C.intybus and M.sativa were the opposite.This indicated that the intrafamily species Z.diploperennis and P.americanum×Purpureum had similar photosynthetic capacities,while the interfamily species C.intybus and M.sativa had significantly different photosynthetic capacities,even though they shared similar WUE and WUEi.There was no significant difference in water contents in the 0-10 and 10-20 cm soil layers below these four forage grasses,showing that they had little effect on soil water content.However,these different grasses did affect soil bulk density.Correlation analysis showed a significant positive correlation between Tr and water content in the 0-10 cm soil layer for all grasses,and the water content of the 10-20 cm soil layer greatly affected their Vpdl.Comparatively,Z.diploperennis and P.americanum×Purpureum had greater Pn,WUE and WUEi,indicating better adaptability to the Karst environment.