岩石边坡坡度对紫花苜蓿根系生长特征及拉拔力的影响

Effect of rocky slope gradient on growth characteristicsand pull-out resistance of Medicago sativa roots

摘要:

为掌握岩石边坡植被恢复过程中,坡度对植物根系生长特征及其固土护坡效果的影响,以京承三期高速公路边坡植被恢复工程为依托,采用根系挖掘法对40°、50°和60°岩石边坡生长3年的紫花苜蓿(Medicago sativa)根系生长特征进行研究,并采用液压式拉力计测定根系拉拔力。结果表明:随着坡度增大,紫花苜蓿主根直径逐渐增大,Ⅰ级和Ⅱ级侧根直径逐渐减小;主根长度比例逐渐减小,侧根长度比例逐渐增大,同时细根(0 mm＜d≤2 mm)的长度比例逐渐增大,中根(2 mm＜d≤5 mm)的长度比例逐渐减小;主根生长方向未随坡度改变而改变;侧根生物量远小于主根生物量,40°边坡条件下主根生物量显著小于50°和60°边坡(P＜0.05)。随着坡度增大,根系拉拔力呈逐渐增大趋势。

Abstract:

The effect of slope gradient on the growth characteristics and slope protection of Medicago sativa roots in the process of vegetation restoration on rocky slopes was studied by investigating the root characteristics of three years old M.sativa growing on 40°,50° and 60° rock slopes using excavating whole root systems method along the Beijing-Chengde Expressway.The pull-out resistance of roots was measured by hydraulic tension meter.The results showed that with the increase of slope gradient,the diameter of taproot tended to increase,the diameter of grade I and grade II lateral roots decreased.With the increase of slope gradient,the length proportion of lateral root tended to increase,taproot decreased,fine root (0 mm＜d≤2 mm) increased,medium root (2 mm＜d≤5 mm) decreases gradually.The growth direction of taproot did not change with the change of slope.The biomass of lateral root was much less than taproot,and under the condition of 40° slope,the biomass of taproot was significantly less than that of 50 ° and 60 ° slopes (P＜0.05).With the increase of slope gradient,the root pull-out resistance increased gradually.