花叶滇苦菜浸提液对3种花卉种子萌发和幼苗生长的化感作用

Allelopathic effects of extracts of Sonchus asper on seed germination and seedling growth of three herbaceous flower species

为探讨花叶滇苦菜与常见草本花卉协同生长过程中的化感作用机制,采用培养皿生物测定法,研究了花叶滇苦菜地上部(DS)和地下部(DX)不同浓度浸提液对二月兰、石竹、观赏油菜3种花卉种子萌发、幼苗生长的生理指标及相关酶活性、丙二醛(MDA)含量的影响,以期为花卉植物大规模应用及杂草生物防治提供理论依据。结果表明:花叶滇苦菜浸提液对3种花卉种子萌发、幼苗生长均呈低浓度促进、高浓度抑制的趋势,在5 g·L^(-1)时2种浸提液中促进效应最大的是二月兰,其次是石竹,均在100 g·L^(-1)浓度下抑制效应达最大。2种浸提液提高了3种花卉幼苗的超氧化物歧化酶(SOD)活性,二月兰、观赏油菜在50 g·L^(-1)时达到峰值,石竹在25 g·L^(-1)时达到峰值,100 g·L^(-1)时均高于对照组,过氧化物酶(POD)和过氧化氢酶(CAT)活性均呈先升高后降低的趋势,丙二醛含量随浸提液浓度的升高而增加。石竹种子POD活性与种子发芽率呈极显著正相关;观赏油菜POD活性与茎长和根长呈显著正相关;二月兰根长与POD、CAT活性呈极显著正相关,CAT活性与茎长和发芽率呈极显著正相关。浸提液对种子萌发和幼苗生长的化感作用综合效应强弱依次为观赏油菜>石竹>二月兰。综上所述,浸提液对3种花卉幼苗细胞膜均具有一定的损伤作用,应尽量避免在花叶滇苦菜危害严重的地块大规模种植3种花卉或者种植前彻底清除杂草。

This study explored the allelopathic mechanisms at play in competition between Sonchus asper and common herbaceous flowers.In this experiment,a petri dish bioassay was used to study the effects of different concentrations of extracts from aboveground and underground parts of S.asper on seed germination,seedling growth activities of related enzymes and malondialdehyde(MDA)content of the three herbaceous flower species Orychophragmus violaceus,Dianthus chinensis and Brassica juncea.It was anticipated the results might lay a foundation for development of biological control methods for weeds.It was found that the extracts of S.asper typically had a promotional effect at low concentration and an inhibitory effect at high concentration on the seedling growth of the three tested flower species.At a concentration of 5 g·L^(-1),the promotional effect of the two extracts was greatest for O.violaceus,followed by D.chinensis,and the inhibitory effect reached a maximum at a concentration of 100 g·L^(-1).The two S.asper extracts increased the activity of superoxide dismutase(SOD)in seedlings of the three tested flower seedlings.For O.violaceus and B.juncea this effect peaked at 50 g·L^(-1),and for D.chinensis the effect peaked at 25 g·L^(-1),and SOD activity remained higher than control at 100 g·L^(-1).The activities of peroxidase(POD)and catalase(CAT)in the tested flower species were increased at low concentrations of S.asper extract and then decreased at higher concentration,while the content of MDA increased with successive increases in the concentration of the extract.There was a very significant positive correlation between POD activity and seed germination rate of D.chinensis,and a highly significant positive correlation between POD activity and stem length and root length in B.juncea.The root length of O.violaceus was significantly positively correlated with the activities of POD and CAT,and stem length and the germination rate of O.violaceus was significantly positively correlated with the activity of CAT.A calculated index of the overall degree of allelopathic activity of the S.asper extracts on seed germination and growth ranked the effects on the tested flower species B.juncea>D.chinensis>O.violaceus.In summary,the extract causes a degree of damage to cell membranes of the three tested flower seedlings,so it would be advisable to avoid the flower planting in land seriously infested with S.asper.