梨园根际土壤的连作化感作用及化感物质成分分析

A study on allelopathy and analysis of allelochemicals in rhizosphere soil in orchards with continuous cropping of pear

【目的】研究连作梨园根际土壤的化感作用并利用气相色谱-质谱联用仪对其化感成分进行分析,为解决梨园连作障碍提供参考。【方法】以连作梨园根际土壤和‘川梨’实生(Pyrus pashia Buch.)幼苗为试材,通过生物测试研究根际土壤化感作用,并进行GC-MS分析。【结果】2种根际土壤水浸提液浓度为0.25 g·m L^(-1)时就对梨幼苗生长产生抑制,且随浓度增加而增强,1 g·m L^(-1)抑制作用最为显著,幼苗株高、叶面积、地上、地下部分鲜重等均显著下降;从2种连作土壤中分别分离出9大类物质78种和10大类77种化学组分,包括烷烃、酯类、醇类、酮类、酚类等物质,最主要的物质种类均为烷烃类,占总成分的38.49%和30.48%,其次是酯类,醇类等;2者均四十烷的相对含量最高,分别为11.22%和8.75%。【结论】连作梨园根际土壤确实存在化感作用,对再植幼苗生长不利,经鉴定其化感成分种类有烷烃类、酯类、酚类、酮类等物质,具体这些化感物质的化感效应及其相关机理尚待进一步研究。

【Objective】To study the allelopathy and identify the allelochemicals in the rhizosphere soils collected from two continuous cropping pear orchards of the Zhonghua pear village and Ji’an town.The study was to discuss the role of allelopathy in continuous cropping obstacle in order to provide reference to solving the problem of pear production.【Methods】Annual Pyrus pashia Buch.seedlings were used as materials for biological test in pot.They were irrigated with three different concentrations of water extraction from the two rhizosphere soils weekly.The concentrations were 0 g·m L-1(control),0.25 g·m L-1,0.5 g·m L-1and 1 g·m L-1.After eight months,the growth indicators of pear seedlings were measured in this experiment.In addition,the ethyl acetate extractions from the two kinds of soils were prepared and a gas chromatography-mass spectrometry instrument was used to analyze the compounds in the rhizosphere soils.【Results】The result of biological test showed that growth of pear seedlings was influenced by irrigation with the extraction,manifesting the allelopathy in rhizosphere soils in continuous cropping pear orchard.Inhibition on growth was presented when the concentration of the extraction just was 0.25 g·m L-1,and the effect increased with the increase in concentration.In comparison with 0.25 g·m L-1,the effects of 0.5 g·m L-1and 1 g·m L-1showed significant difference(P<0.05),and 1 g·m L-1exhibited significant inhibition on growth,as reflected by seedling height,leaf area,the fresh weights of the aboveground and undergroundparts,and root to shoot ratio.They were significantly decreased(P<0.05)compared with the other treatments.And among them,leaf area,underground fresh weight and root to shoot ratio were 23.1%,25%and14.6%lower than control,respectively.Results of GC-MS analysis showed that 78 kinds of compounds in9 categories and 77 kinds in 10 categories were respectively detected in the two kinds of continuous cropping rhizosphere soils,including alkanes,esters,alcohols,ketones,phenols and so on.52 kinds of compounds of them were similarly detected in both rhizosphere soils.The results also indicated that alkanes were the main category in the soils accounting for 38.49%and 30.48%of the total relative content.The second major compounds were esters and alcohols,and their relative contents were far less than alkanes.The relative content of tetracontane was the highest,11.22%and 8.75%respectively in soils from the Zhonghua pear village and Ji’an town.The second most abundant mutual compounds were undecane,docosanoic,tetratetracontane,hexatriacontane,pentanoic acid ethyl ester,ethyl butyrate,13-docosenamide,(Z)-,gamma-sitosterol,2,6,10,14,18,22-tetracosahexaene,2,6,10,15,19,23-hexamethyl-,(all-E)-and stigmastane.Compounds like 1,2-benzenedicarboxylic acid,diisooctyl ester,dibutyl phthalate,1,2-Benzenedicarboxylic acid,bis(2-methylpropyl)ester and butylated hydroxytoluene were allelochemicals reported by previous researchers.【Conclusion】The allelopathy is confirmed in the rhizosphere soils from continuous cropping pear orchard.GC-MS analysis has identified the compounds,which have negative effects on the replanted seedlings and they may play a role in allelopathy.The categories of allelochemicals detected in the two kinds of rhizosphere soils are alkanes,esters,phenols,ketones and so on.The specific effects of these allelochemicals need to be further researched in the future.