连作花生土壤中酚酸类物质的检测及其对花生的化感作用

The contents of phenolic acids in continuous cropping peanut and their allelopathy

研究了南方红壤区不同连作年限花生土壤中酚酸物质的种类、含量,及其对花生生长的影响。结果表明:连作花生土壤中对羟基苯甲酸、香草酸和香豆酸随着连作年限的增加而增加,连作10a后3种酚酸总量达11.09mg·kg-1干土,显著高于连作3a和6a的土壤;而土壤中香豆素和苯甲酸含量比较低,且变化没有规律。所有酚酸处理组对花生幼苗的株高和根长表现出抑制作用,对花生幼苗地下部的干鲜重均表现出"低促高抑"的特点。香草酸和香豆酸处理组对花生幼苗地上部的干鲜重表现出"低促高抑"的特点,其他处理组均表现出抑制作用。花生幼苗根系活力随着酚酸处理浓度的增加而降低,花生幼苗的超氧化物歧化酶活力(SOD)、过氧化物酶活力(POD)、丙二醛含量(MDA)则随着酚酸浓度的增加而增加。与只用茄腐镰刀菌孢子悬液浸泡花生种子的对照相比,加入酚酸后,花生种子的病原菌的感染率随着酚酸浓度的增加而增加,发芽率则随着酚酸浓度的增加而下降。以上结果说明,酚酸物质可以抑制花生幼苗的生长和提高花生的发病率,可能是因为酚酸物质破坏花生细胞膜的完整性而使病原菌入侵,影响花生生长,产生连作障碍。

In order to find the reason that the obvious continuous cropping obstacles found in peanut,experiment was designed to study this phenomenon in this paper.The soil samples were collected from four adjacent continuous cropping peanuts field in red soil of south China which were continuously cropped for 3,6,10 and 15 yeras respectively and the control was the abandoned farmland belonging to the same parent material at March 20,2009.Subsequently,the kinds and content of phenolic acids of continuous cropping peanuts field were detected.The results showed that three exogenous phenolic acids of p-hydroxybenzoic acid,vanillic acid and coumalic acid and their mixture at three different concentrations affected on the incidence of peanut seed infected with Fusarium solani and the incidence of peanut seed germination infecting with F.solani,and the growth and protecting enzymy activities of peanut seedlings by tissue culture.The results also revealed that soil p-hydroxybenzoic acid,vanillic acid and coumalic acid accumulated gradually with the increasing year of continuous peanut cropping.The total amounts of three phenolic acids reached 11.09mg·kg-1dry soil after 10 years cropping,which was significantly higher than that after 3 or 6 years cropping and similar to 15 years cropping.However,the amounts of coumarin and benzoic acid were very low in all detected soil samples.Plant height and root length were inhibited with all the treatments.The underground fresh and dry weight of peanut seedlings were promoted at lower level and inhibited at higher level of phenolic acids.The aboveground fresh and dry weight of peanut seedlings were inhibited at all levels except that vanillic acid and coumalic acid promoted at lower level.In addition,root activities of peanut seedlingdecreased and plant Superoxide dismutase（SOD） activities,Perpxodase（POD） activities and Malondialdehyde（MDA） contents rose with increasing concentration of phenolic acids comparing with the control.This result showed that the cell membrane of peanut seedling was destroyed and induced the defense reaction and this maybe provide some invasion ways to pathogen.Comparing with the control of peanut seeds treated with F.solani spore suspension,the incidence of peanut seed infected with F.solani increased and the incidence of peanut seed germination reduced with increasing concentration of phenolic acids.These results indicated that phenolic acids could inhibit the growth of peanut seedling,increase the incidence of peanut infected with pathogen and decrease the incidence of peanut seed germination infecting with pathogen.Phenolic acids existed in continuous peanut cropping soils would destroy the cell membrane of peanut seedlings,and then the peanut pathogen invaded the seedlings.This would led to the inhibition of peanut seedling growth,and continuous cropping obstacles would happen.