Preliminary Study On Relationship Between Leaf Yellowing And Allelopathy In Pear Tree

China is one of the fastest-growing pear industries in the world.The pear industry accounts for 70% of the world’s pear industry every year and is the largest pear producer in the world.In recent years,with the rapid development of pear industry,pear yield and quality decreased due to the yellowing of pear leaves.At present,some studies have shown that the yellowing of pear leaves is related to the allelochemical effect of soil.Because the study of allelochemical effect has gradually deepened,the study of allelochemical effect has become a new hotspot in the field of yellowing of fruit leaves,but there are still some problems that need to be confirmed,especially the environmental behavior and accumulation mechanism of allelochemicals in soil,the factors that produce allelochemicals and the influence on soil ecosystem are all the focus of research and demonstration.In order to reveal the relationship between yellowing of pear leaves and soil allelopathy,this study took the rhizosphere soil,root soil and surfce soil of fruit orchard in xiao county,suzhou city,anhui province as the test soil to explore the allelochemical components and differences between them,so as to realize the sustainable and healthy development of pear industry.The growth phenotype of the seedlings was observed by watering the seedlings with normal soil and yellowing soil extract.Using GC-MS for allelochemical analysis,the allelopathic substances in soil were determined by data comparison,and the results of the experiment were as follows:(1)Through the extraction of root soil extracts from normal pear trees and yellow pear trees,different concentrations of gradients of extraction solution were set up to irrigate the seedlings.After 60 days of irrigation,the phenotype of the seedlings was observed.the normal soil extracts irrigated the seedling of du pear with low concentration of seedling phenotype leaves light green and high concentration of seedling leaves dark green.The results show that the higher the concentration of yellowing soil extract,the stronger the inhibition effect,the lower the concentration of normal soil extract,the higher the concentration,which indicates that the accumulation of organic matter in pear soil has a self-toxic effect on the growth of pear seedling,thus laying a foundation for the study of the allelochemical effect of pear soil.(2)Using ethyl acetate as extractant,GC-MS analysis was carried out on the extraction solution of root soil,rhizosphere soil and root plexus soil.After analyzing the organic components of rhizosphere soil and root plexus soil,32 allelochemicals were found in rhizosphere soil.After analyzing the organic components of root soil and rhizosphere soil,it is concluded that there are 12 allelochemicals in root soil.By comparing the allelochemicals of various plants,the root exudates and rhizosphere allelochemicals of pear are derived from benzoic acid,such as Dibutyl phthalate,bis(2-ethylhexyl)phthate,etc.(3)The root and rhizosphere soils were determined to have 11 allelochemicals that may cause yellowing of leaves by previous analysis and analysis of experimental data.The phenotype of leaves was observed by hydroponic pear seedling experiment with exogenous compounds with different concentration gradient.In the experiment,it was found that the allelochemicals of caprolactam,1,3,5-triene,2,4-di-tert-butylphenol(2,4-di-t-butylphenol)had a strong effect on the leaf yellowing of pear seedlings.By detecting the GC-MS organic constituents of the common chemical fertilizer in pear,it was found that the chemical fertilizer had 1,3,5-triylene isomers,1,2-trimethylbenzene(1,2-terylene,4-trimethyl-thy).