玉米根系分泌物对连作花生土壤酚酸类物质化感作用的影响

为探究玉米花生间作系统中玉米根系分泌物对连作花生土壤的酚酸类物质化感作用的影响机制，利用CH2Cl2提取了玉米抽雄期根系分泌物，通过室内模拟培养法，研究了玉米根系分泌物对含有不同浓度肉桂酸、邻苯二甲酸及对羟基苯甲酸3种酚酸类物质土壤的微生态环境的影响。结果表明，酚酸类物质均显著降低了土壤微生物量碳和氮的含量，抑制了土壤微生物活性，土壤酶（脲酶、酸性磷酸酶和蔗糖酶）活性和养分含量（碱解氮、有效磷和有效钾）亦显著降低，且浓度越高化感抑制作用（RI＜0）越强（P＜0.05）。玉米根系分泌物可降低酚酸类物质对土壤微生物活性、微生物量、酶活性及养分含量的化感指数，以低浓度处理的降幅较大，且在处理第5 d和10 d显著增加了3种酚酸类物质处理的土壤呼吸强度、酶活性、微生物量及养分含量（P＜0.05）；不同酚酸类物质中，以邻苯二甲酸所受影响最大。整个培养时期，玉米根系分泌物对酚酸类物质化感作用的影响以处理第5 d最强，随后呈减弱趋势。3次取样，土壤微生物量、微生物活性、酶活性和养分含量的化感指数分别降低10.03%~64.13%、9.72%~57.51%、13.16%~78.85%和5.88%~59.71%。玉米根系分泌物可通过提高土壤微生物量、微生物活性及养分含量，来降低肉桂酸、邻苯二甲酸和对羟基苯甲酸对土壤微生态环境的化感作用。结果为玉米花生间作缓解花生连作障碍技术提供一定的理论依据。

Effects of Maize Root Exudates on Allelopathy of Phenolic Acids in Soil of Continuous Cropping Peanut

In order to explore the mechanism of the effect of maize root exudates on the allelopathic of phenolic acids in continuous cropping peanut soil in the maize intercropping peanut system, root exudates of maize during tasseling stage were extracted by CH2Cl2, and the effects of maize root exudates on the micro-ecological environment of soil containing different concentrations of cinnamic acid, phthalic acid and p-hydroxybenzoic acid through indoor simulated culture method were investigated. The results showed that phenolic acids significantly reduced soil microbial biomass carbon and nitrogen contents, inhibited soil microbial activity, soil enzyme (urea, acid phosphatase and sucrase) activities and nutrient content (alkaline nitrogen, available phosphorus and the effective potassium), and the higher the concentration, the stronger the allelopathy inhibition (P<0.05). The allelopathic index of phenolic acids to soil microbial activity, microbial biomass, enzyme activity and nutrient content were decreased by the root exudates of maize, and the decrease of low concentration treatment was larger. Moreover, the soil respiration intensity, enzyme activity, microbial biomass and nutrient content of the three phenolic acids treatments were significantly (P<0.05) increased on the 5th and 10th day of root exudates treatments, and the allelopathic inhibition of phthalic acid on soil was the most affected among three phenolic acids. During the whole culture period, the effect of maize root exudates on the allelopathy of phenolic acids was the strongest on the 5th day, followed by the weakening trend. The allelopathic index of soil microbial biomass, microbial activity, enzyme activity and nutrient content decreased by 10.03%~64.13%, 9.72%~57.51%, 13.16%~78.85% and 5.88%~59.71%, respectively after root exudates treatments. Maize root exudates can reduce the allelopathy of cinnamic acid, phthalic acid and p-hydroxybenzoic acid on soil micro-ecological environment by increasing soil microbial biomass, microbial activity and nutrient content. Present research provided a theoretical basis for the technology of maize intercropping peanut to alleviate the continuous cropping obstacle of peanut.