香豆素对多花黑麦草种子萌发和幼苗生长化感作用的机理研究

为探明化感物质香豆素的化感抑草作用机理,采用实验室培养皿生物监测法研究香豆素对多花黑麦草种子萌发及幼苗生长过程中主要生长和生理生化指标的影响,观察了种子和幼苗茎秆的超微组织结构变化。结果表明,与对照相比,香豆素显著降低了多花黑麦草种子的发芽势、根长、根干重、茎长和茎叶干重等生长指标(P0.05);香豆素处理显著降低了吲哚乙酸氧化酶(IAAO)活性和叶绿素含量(P0.05),同时显著提高了可溶性糖含量(P0.05),以及4和6d种子的蛋白质浓度(P0.05);且在前期促进了多花黑麦草幼苗的过氧化氢酶(CAT)活性、抑制了过氧化物酶(POD)活性,而后CAT降低,POD先升高后降低(P0.05),淀粉含量升高。100μg/mL的香豆素水溶液只能在多花黑麦草种子发芽和幼苗生长初期可以很大限度的起到抑制作用,但不足以使其致死。香豆素抑制种子胚乳养分的分解与供应,破坏胚乳细胞的细胞膜、细胞壁,同时可能使细胞失水而导致质壁分离。

Effect of coumarin on Italian ryegrass seed germination and seedling growth

To study the mechanism of allelopathy,the effects of coumarin on Italian ryegrass seed germination and seedling growth were evaluated in a sand-culture experiment.Compared with the control,coumarin treatment significantly (P＜0.05) reduced the germination rate,root length,root dry weight,stem length,stem dry weight,and leaf dry weight of Italian ryegrass.The seedlings treated with coumarin showed significantly decreased indole acetic acid oxidase activity and lower chlorophyll content,compared with those in the control.The coumarin treatment also significantly (P＜0.05) increased the water soluble carbohydrate content and protein concentration in seeds on days 4 and 6,increased catalase activity and starch content,and decreased peroxidase activity in Italian ryegrass seedlings during the early growth period.The results showed that an aqueous coumarin solution at a concentration of 100μg/mL could control Italian ryegrass seed germination and seedling growth at the early stage,but it did not have a lethal effect.Coumarin inhibited endosperm function,disrupted the nutrient supply for seed germination,and destroyed cell membranes and cell walls in the endosperm,possibly leading to plasmolysis with water loss from cells.