五种高速公路边坡绿化植物的生理特性及抗旱性综合评价

采用盆栽控制土壤水分,测定不同程度水分胁迫梯度下5种高速公路边坡绿化植物的叶水势、光合作用参数及叶绿素荧光参数,并以水分胁迫下各生理指标的平均变化速率为原始数据进行抗旱性综合评价。结果表明:(1)随着水分胁迫的加强,5种植物的ΨL、Pn、Tr、GS、Fv、Fm、Fv/Fm、Fv/Fo均逐渐下降,Fo逐渐升高,WUE先升后降,Ci先降后升,不同生理指标的变化幅度及拐点有一定差异;平均变化速率相对较小的是八宝景天和马蔺,较大的是肥皂草和太行菊;(2)根据水分胁迫下Gs和Ci变化方向的差异判断八宝景天、马蔺以W2作为Pn降低由气孔限制转为非气孔因素的分界线,五叶地锦、肥皂草和太行菊以W1为分界线,八宝景天、马蔺在W2时WUE最高,五叶地锦、肥皂草和太行菊在W1时最高;(3)5种植物抗旱性大小排序为:八宝景天>马蔺>五叶地锦>太行菊>肥皂草,聚类分析结果为:八宝景天、马蔺为强抗旱植物,五叶地锦为中抗旱植物,太行菊、肥皂草为弱抗旱植物。

Physiological characteristics and comprehensive evaluation of drought resistance in five plants used for roadside ecological restoration

A test of potting methods used to control soil water was applied to study the physiological characteristics and drought resistance of five plants used for highway shoulder greening and ecological restoration in northern China.Leaf water potential,photosynthesis parameters and fluorescence parameters of five plants were measured under four levels of water stress.The drought resistance of the plants was evaluated to study the average rate of change in various parameters. The results show:(1) as water stress increased,leaf water potential(ΨL),net photosynthesis(Pn),transpiration(Tr),and stomatal conductance(GS) of the five plants gradually decreased;as water stress increased,water use efficiency(WUE) of the five plants first increased and then decreased but the internal CO2(Ci) of the five plants first decreased and then increased.There were some differences in the changing amplitudes and inflection points of the physiological indices.Sedum spectabile and Iris lactea var.chinensis had relatively small average rates of change,while Opisthopappus taihangensis and Saponaria officinalis had relatively large average rates of change.(2) The Ci of S.spectabile and I.lactea var.chinensis reached a minimum value under moderate water stress(W2),while the Ci of Parthenocissus quinquefolia,O.taihangensis and S.officinalis reached a minimum value under mild water stress(W1).Changes in Gs and Ci under water stress were reflected in changes in Pn;the decrease in Pn observed in S.spectabile and I.lactea var.chinensis were mainly caused by stomatal limitation resulting from the change from a normal water supply(CK) to moderate water stress(W2),while non-stomatal factors caused the changes observed under severe water stress(W3).The decrease in Pn in P.quinquefolia,O.taihangensis and S.officinalis was mainly caused by stomatal limitation under normal water supply conditions(CK) and mild water stress(W1),and by non-stomatal factors under moderate water stress(W2) and severe water stress(W3).WUE of S.spectabile and I.lactea var.chinensis had the highest under moderate water stress.WUE of P.quinquefolia,O.taihangensis and S.officinalis had the highest under mild water stress.(3) As water stress increased,initial inflorescence(Fv),maximum inflorescence(Fm),the ratio of variable to maximum(Fv/Fm),or initial inflorescence(Fv/Fo) of the five plants decreased gradually and Fo of the five plants increased gradually.This indicated the energy of PSII was transformed into a reduction in photochemical energy and additional energy was lost as heat and through fluorescence,which led to reduced photosynthesis.(4) The drought resistance of the five plants was evaluated by principal component analysis based on the average rate of change of each plant under water stress.The comprehensive drought evaluation indices of S.spectabile and S.officinalis/O.taihangensis were the highest(0.898) and lowest(0.125),respectively.The drought resistance order follows: S.spectabile > I.lactea var.chinensis > P.quinquefolia > O.taihangensis > S.officinalis.The results of cluster analysis shows S.spectabile and I.lactea var.chinensis were the most drought resistant plants,P.quinquefolia exhibited a medium level of drought resistance,and O.taihangensis and S.officinalis had poor drought resistance.