连作烟草根际土壤化感潜力评价及化感物质鉴定

以不同植烟年限的烟草根际土壤为材料,设置6个不同浓度的土壤水浸提液处理,分别对莴苣和烟草进行生物测试,同时用2g· mL-1的正已烷、乙酸乙酯、氯仿、丙酮和甲醇5种不同极性有机溶剂根际土壤浸提液进行化感潜力评价；采用气相色谱和质谱联用技术(GC-MS)鉴定烟草根际土壤甲醇浸提液所含的有机化合物.结果表明:(1)烟草根际土壤水浸提液对莴苣和烟草胚根生长的影响表现为低促高抑的双重浓度效应,并且随着种植年限的增加抑制作用增强.(2)浓度为2g·mL-1的烟草根际土壤甲醇浸提液对莴苣和烟草胚根的生长抑制作用最强,正已烷、氯仿、乙酸乙酯土壤浸提液基本上无抑制现象.(3)鉴定了不同种植年限烟草根际土壤甲醇浸提液中所含的有机化合物,其中种植1年、种植3年的烟草根际土壤甲醇浸提液中存在烷烃、醇、酮、酸、酯、酚、萜烯类以及多环芳烃等有机化合物.

Allelopathic evaluation of continuous cropping tobacco rhizospheric soil and allelochemical identification

Tobacco rhizospheric soil of different planting years was used to explore allelopathic effects and allelochemical identification.The treatments of 0,5,1,0.5,0.2 g·mL–1 aqueous extractions and 2 g·mL–1 different organic solvent extractions from the rhizospheric soil were bioassayed using Lettuce(Lactuca sativa) and tobacco in laboratory.The allelochemicals(autotoxicity compounds) in methanol extraction of rhizospheric soil were identified by gas chromatography-mass spectrometry(GC-MS).Results showed that(1) radical growth of Lettuce and tobacco seedlings was all affected by aqueous extractions of the rhizospheric soil,showing stimulative effect at low dosage and inhibitory effect at high dosage,and the inhibitory effect was increased as the continuous cropping years increased;(2) n-hexane,chloroform and ethyl acetate extraction of the rhizospheric soil showed no allelopathic effects on radical growth of Lactuca sativa and tobacco seedlings.Methanol extraction of the rhizospheric soil had the strongest allelopathic effect on target plants with concentration of 2 g·mL–1,which indicated that allelopathic compounds of the rhizospheric soil might come from some strong polar compounds;and(3) by GC-MS determination,the compounds of methanol extraction from rhizospheric soil after continuous cropping for one season and three seasons respectively were alkane,alcohols,alcohols,acid,ester,phenol,terpene and polycyclic aromatic hydrocarbons etc.,most of which had been reported as allelochemicals.