山药化感物质对山药和玉米种子萌发及幼苗生长的影响

本研究以山药零余子和玉米种子为受体材料,采用生物测试方法,以发芽率、发芽势、发芽指数、根长、茎长和干重为种子萌发和幼苗生长参数,研究山药植株腐解液、根系分泌物和根际土浸提液对受体材料的化感效应,旨在探明山药化感物质的释放途径,探索山药化感物质对不同受体材料的化感作用,为揭示山药连作障碍的机理奠定基础。结果表明：山药植株腐解液和根系分泌物对山药和玉米均有强烈的化感抑制作用,根际土浸提液的化感作用较微弱,化感作用强度为根系分泌物?植株腐解液?根际土浸提液,山药根系分泌物和植株腐解液含有丰富的化感物质,可能是山药自毒物质的主要来源之一,是山药化感物质研究的可靠基础材料;在试验设置的浓度范围内,山药化感物质对受体材料的抑制作用与其质量浓度呈正比,3种浸提液对受试材料的化感作用存在低促高抑的浓度效应,低于100 mg/mL时有微弱的促进作用,大于等于100 mg/mL就会产生强烈的抑制作用,随着浓度升高,化感抑制作用强度越大;山药的化感物质对玉米幼苗生长抑制强度大于种子萌发期,山药则相反;结合种子萌发和幼苗生长的综合化感效应指数,2种受试作物对山药化感作用的敏感程度为自毒作用强于他感作用。

Allelopathic Effects of Yam on Seed Germination and Seedling Growth in Yam and Maize

Yam and maize were used as the receptor materials to investigate the allelopathic effects of the decomposition solution, root exudates and rhizosphere soil extracts acquired from yam plant. By biological test methods, germination rate, germination potential, germination index, root length, stem length and dry weight were examined to elucidate the releasing pathway of yam allelochemicals and the allelopathic effects of yam allelochemicals on different receptor materials. Results showed that the decomposition solution of yam plant and root exudate had strong allelopathic inhibition on yam and maize, but the allelopathic effect of rhizosphere soil extract was weak, and the allelopathic effect intensity was root exudates ? plant decomposition solution ? rhizosphere soil extract.The germination rate, germination potential, germination index, root length, stem length and dry weight of yam and maize were significantly inhibited. The degree of inhibition of the six indicators of yam was as follows: germination potential > germination index > root length > germination rate > dry weight > stem length. The inhibition degree of the six indicators of maize was root length > dry weight > stem length > germination potential > germination index > germination rate. On the whole, the inhibition degree of yam was greater than that of maize. Yam root exudates and plant decomposition liquid were rich in allelochemicals, which might be one of the main sources of yam autotoxic substances, and were reliable basic materials for the study of yam allelochemicals. In the concentration range set in the experiment, the inhibitory effect of the allelopathic substances on the tested materials was directly proportional to the mass concentration. The allelopathic effect of the three extracts on the tested materials exerted a concentration effect with low promotion and high inhibition. 100 mg/mL was the critical concentration of yam autotoxin effect. When it was lower than 100 mg/mL, it had a weak promotion effect, and when it was greater than or equal to 100 mg/mL, it would have a strong inhibition effect, the intensity of allelopathy inhibition increased with the increase of concentration. The inhibitory intensity of the allelochemicals of yam on the growth of maize seedlings was greater than that of seed germination, while it was the opposite in yam. In summary, according to the comprehensive allelopathy response index of seed germination and seedling growth, the susceptibility of the two tested species to the allelopathic effect of autotoxicity was stronger than allelopathy.