鬼针草与含羞草化感作用及其入侵性的研究

采用培养皿滤纸法研究入侵植物鬼针草与含羞草根、茎、叶浸提液对种子萌发和幼苗生长的影响,从化感角度揭示外来植物的入侵机制。结果表明:1)鬼针草根、茎、叶浸提液随浓度升高显著抑制鬼针草和含羞草种子萌发,高浓度(0.04 g·mL^-1)的叶浸提液使萌发率降低了67%~87%;高浓度(0.04 g·mL^-1)的含羞草叶浸提液使其种子萌发率降低了21.7%,但对鬼针草种子萌发影响较小。2)鬼针草和含羞草根长随2种植物根、茎、叶浸提液浓度的升高而降低,尤其是高浓度的叶浸提液有较强抑制效应。3)各浓度的鬼针草根、茎、叶浸提液均能降低含羞草茎长,高浓度的叶浸提液抑制效应最强;高浓度(0.04 g·mL^-1)的含羞草茎和叶浸提液抑制鬼针草茎长,中等浓度(0.02~0.03 g·mL^-1)的根和叶浸提液促进鬼针草茎长;含羞草各器官浸提液对其茎长的抑制作用随浓度增大略有增强。4)鬼针草各器官浸提液(尤其叶浸提液)抑制自身根冠比,促进含羞草根冠比;含羞草各器官浸提液轻微降低自身根冠比,显著降低鬼针草根冠比。5)鬼针草对自身种子萌发率、根长及根冠比的化感强度大于鬼针草他感强度;鬼针草对含羞草茎长的化感强度大于其自感强度,也大于含羞草他感强度;含羞草对鬼针草根长及根冠比的化感强度大于其自感强度,也大于鬼针草他感强度。鬼针草主要通过抑制含羞草茎长,增强入侵性,而含羞草主要通过抑制鬼针草根的生长,增大竞争力。

Allelopathy and invasiveness of Bidens pilosa and Mimosa pudica

This research aimed to determine the allelopathic effect of the invasion mechanism of the exotic plants Bidens pilosa and Mimosa pudica. The effects of extracts from the roots, stems and leaves of both B. pilosa and M. pudica on seed germination and seedling growth (root length, stem length and root∶shoot ratio) were studied using a petri dish filter paper method. It was found that: 1) B. pilosa extracts had a large concentration dependent effect on the seed germination of both B. pilosa and M. pudica, with leaf extracts being the most potent (67%-87% germination inhibition at the highest tested concentration). M. pudica leaf extracts at high concentration reduced germination of their own seeds by 21.7% but had no significant effect on germination of B. pilosa seeds. 2) Root, stem and leaf extracts (but especially leaf extracts) of both species all induced a concentration dependent reduction in root length of their own seedlings and of the other species. 3) Root, stem and leaf extracts of B. pilosa strongly reduced stem length of M. pudica at all tested concentrations. Only stem and leaf extracts of M. pudica at high concentrations showed any allelopathic effect on stem length of B. pilosa. Root and leaf extracts of M. pudica at medium concentrations enhanced stem growth of B. pilosa. M. pudica extracts had a moderate, concentration dependent autotoxicity effect on their own seedling stem length. For B. pilosa, only leaf extracts at high concentration reduced stem length of their own seedlings. 4) B. pilosa extracts (especially leaf extract) induced a strong concentration dependent reduction of root∶shoot ratio of their own seedlings while all three extracts enhanced root∶shoot ratio of M. pudica seedlings. M. pudica extracts caused only a mild reduction in root∶shoot ratio of their own seedings, but a substantial reduction in root∶shoot ratio of B. pilosa seedlings. 5) An index of allelopathic or autotoxicity intensity was calculated from the data. Autotoxicity intensity of B. pilosa on its own seed germination rate, root length and root-shoot ratio was greater than that of M. pudica, while the allelopathy intensity of B. pilosa on the stem length of M. pudica was greater than that of M. pudica on B. pilosa, and was also greater than its autotoxicity intensity. The intensity of allelopathic effects of M. pudica on the root length and root∶shoot ratio of B. pilosa was greater than the self-inhibition of B. pilosa, and was greater than its self-toxicity intensity. B. pilosa mainly inhibited the stem length of M. pudica to enhance its invasiveness, while M. pudica mainly inhibited the growth of B. pilosa roots to increase its competitiveness.