FIGURE 3 Comprehensive allelopathic effect index ofElymus nutans extracts on highland crops.
3.2 Autotoxicity of Elymus nutans and its allelopathic potential on perennial grasses
The effects of the three types of extracts on germination force of perennial grasses were shown in Figure 4a. The control’s germination force of Siberian wildryegrass was greater than 65%, and that of other four grasses were less than 50%, suggesting Siberian wildryegrass seed has strong vitality and the emergence is uniform. The pieces extract treatment resulted significant decrease of germination force of all tested perennial grasses, with a biggest decrease by 58.8% of Chinese festuca and smallest decrease by 14.6% of Kentucky bluegrass compared to control. The pieces extracts treatment leads to significant decrease of germination force of Siberian wildryegrass, Chinese fescue and Kentucky bluegrass than those of whole extracts treatment. Root zone soil extracts had no significant allelopathic effect on germination force of Kentucky bluegrass and crymophila bluegrass, but significantly lowered the germination force of Siberian wildryegrass, Chinese fescue, and drooping wildryegrass itself.
The germination percentage of the control of the five perennial grasses were less than 70%. The germination percentage of perennial grasses was decreased by the three kinds of extracts (Figure 4b). The whole extracts decreased the germination percentage of drooping wildryegrass, Chinese fescue, Kentucky bluegrass and crymophila bluegrass except Siberian wildryegrass. The pieces extracts and root zone soil extracts showed significant inhibitory on germination percentage of Chinese fescue and crymophila bluegrass compared to control and whole extracts.
The germination indexes of all control were less than 40, indicating lower seed vigor of the tested perennial grasses (Figure 4c). The reduction of germination index by the whole extracts varied with donor plants. The biggest drop occurred in drooping wildryegrass and crymophila bluegrass. The pieces extracts reduced Siberian wildryegrass (38.1%), Chinese fescue (47.3%), and crymophila bluegrass (40.2%), significantly. The root zone soil extracts increased the germination index of Kentucky bluegrass by 24.3%, but decreased that of other four grasses.