三裂叶蟛蜞菊对花生化感作用的生理生化机理

Physiological and Biochemical Mechanism of Allelopathy of Wedelia trilobata L. on Peanut(Arachis hypogaea L.)

三裂叶蟛蜞菊(WedeliatrilobataL.)是华南地区的重要杂草和园林绿化植物。本文研究了三裂叶蟛蜞菊水提液对花生种子萌发和幼苗生长过程中一些生理过程的影响。结果表明,三裂叶蟛蜞菊各器官水提液浸种显著降低了萌发花生种子过氧化物酶活性和脂肪酶活性,提高了质膜透性,进而使萌发花生种子的活力和呼吸速率显著降低。其中三裂叶蟛蜞菊根、茎、叶和全植株水提液使萌发花生种子过氧化物酶活性分别降低了32.80%、39.48%、32.37%和34.40%,使脂肪酶活性分别降低了21.19%、26.69%、24.15%和22.88%。在花生植株幼苗生长过程中,喷淋三裂叶蟛蜞菊各器官水提液极显著地降低了花生根系干物重、单株根瘤数、叶片叶绿素含量、净光合速率和单株干物重;其中三裂叶蟛蜞菊叶水提液分别使花生叶片叶绿素含量、净光合速率和单株干物重降低31.95%、32.65%和37.93%。喷淋三裂叶蟛蜞菊各器官水提液还极显著地抑制了花生氮素代谢中两种关键酶—硝酸还原酶和谷氨酰胺合成酶的活性,使叶片全氮含量有所下降。三裂叶蟛蜞菊各部分水提液对萌发花生种子化感作用的大小顺序是:茎>叶>全株>根系;而对花生幼苗,化感作用的大小顺序则是:叶>茎>全株>根系。

Wedelia trilobata L. is an important weed and garden herb in South China. The allelopathic effects of aqueous extracts of W. trilobata on the physiological activities of germinating seeds and seedling of peanut were studied. The results showed that the water extracts of root, stem, leaf and the whole plant of W. trilobata reduced the activities of peroxidase by 32.80%, 39.48%, 32.37% and 34.40%, respectively. They reduced the activities of lipase by 21.19%,26.69%,24.15% and 22.88%, respectively. They also significantly increased the membrane permeability, inhibited the respiratory rate and the seed activity. Watering peanut seedlings with the aqueous extracts of W. trilobata resulted in the reduction in dry root weight, numbers of nodule, the leaf chlorophyll content, net photosynthetic rate and the dry weight per plant. Aqueous extract of the leaves reduced the chlorophyll of peanut leaves, net photosynthesis rate and dry weight by 31.95%,32.65% and 37.93%, respectively. They also significantly decreased the activities of nitrate reductase (NR) and glutamine synthetase (GS), the two key enzymes concerning nitrogen metabolism in peanut. The inhibitory effects of aqueous extract of the three organs and whole plant on germinating seeds of peanut were: stem >leaf > whole plant > root, on the seedling growth of peanut were: leaf >stem> whole plant > root.