五爪金龙凋落叶腐解物的化感潜力研究

Allelopathic potentional of early decomposition of leaf litter of Ipomoea cairica

采用莴苣种子为受体,测试了五爪金龙凋落叶早期腐解物的化感作用,并与其鲜叶及凋落叶的化感潜力进行了比较分析。结果如下:凋落叶40d的腐解物、鲜叶及凋落叶的水提取液均具有较强的化感潜力,并表现出低促高抑的浓度效应,在FW0.1g﹒mL-1高质量浓度下的综合化感抑制强度为凋落叶未能加土壤的腐解物>鲜叶>凋落叶加土壤的腐解物>凋落叶,而在FW0.005g﹒mL-1低质量浓度下的综合化感促进作用是凋落叶>鲜叶>凋落叶加土壤的腐解物>凋落叶未加土壤的腐解物。鲜叶的抑制强度较凋落叶的大,表明叶片在衰老过程中抑制作用减弱。凋落叶未加土壤仅在空气微生物作用下的腐解物抑制作用最强,促进作用最小,而加入土壤后在土壤微生物作用下的腐解物的抑制作用却有所减弱,抑制强度介于鲜叶和凋落叶的之间,促进作用却小于鲜叶和凋落叶,说明凋落叶腐解过程中微生物的参与对化感作用产生了复杂的影响。

Ipomoea cairica,is a serious invaded weed in South China. The allelopathic potentional of water soluble compounds from early （40 days） decomposition of leaf litter,fresh leaf and leaf litter of I. cairica were examined. Lettuce seeds （Lactuca sativa）,the common allelopathy bioassay system,were germinated in the presence of aqueous extracts,percent seed germination and root length of the treated seedlings were measured for evaluating the allelopathic potential. Results showed that allelopathic effects could be produced during the decomposition of leaf litter. The aqueous extracts from early decomposition with not soil had the highest inhibitory effects,which significantly inhibited seed germination and root growth of lettuce with increasing of extracts concentration; but the extracts from decomposition with soil had less inhibitory effects,its allelopathy inhibition was between that of fresh leaf and leaf litter,these indicated that microorganisms,including aerial and edaphic microorganisms,could produce complicated influence on the liberation or transformation of allelopathic chemicals in the process of decomposition of leaf litter. The aqueous extracts from fresh leaf had greater inhibitory effects than that of leaf litter,which indicated that allelopathic inhibitory effects would reduce with the decline of leaf. The higher allelopathic inhibitory effects of fresh leaves,leaf litter and their decomposition may play an important role in the processes of survival and success invasion of I. cairica.