Effects Of Areca Catechu L.intercropping With Pandanus Amaryllifolius Roxb.on Soil Microbial Community Structure And Main Aroma Components Of Pandanus Amaryllifolius Roxb.

Areca catechu L.(abbr.areca nut)intercropping Pandanus amaryllifolius Roxb.(abbr.pandan)is the main cultivation mode for improving the quality and efficiency of tropical agriculture,and it is also a mode of high-efficiency tropical agriculture.Explore the changing laws and the correlation among soil environmental factors,soil microbial communities and aroma components of pandan under intercropping mode can provide theoretical support for improving the soil environmental factors and the quality of pandan.The soil physicochemical properties,soil enzyme activities,soil microbiomes,and aromatic properties under areca nut monocropping,pandan monocropping and areca nut intercropping pandan treatments were investigated for two consecutive years in Qionghai,Lingshui and Wanning,Hainan Province in this experiment.The aroma components of pandan were measured and analyzed to explore the effect of intercropping mode on the soil microbial community structure and aroma components of pandan.The results are as follows:1.Compared with areca nut monocropping,the intercropping mode of areca nut and pandan significantly increased the conductivity(by 38.01%,same below),soil bulk density(9.40%)and total phosphorus(9.95%),and significantly decreased soil p H(reduced by0.08,the same below),soil organic matter(23.14%),available potassium(63.90%),alkalihydrolyzable nitrogen(12.02%)and total nitrogen(15.13%);intercropping significantly increased soil p H(increased 0.57 the same below),electrical conductivity(22.39%)soil bulk density(8.43%),while significantly reducing soil organic matter(17.09% reduction,the same below),available potassium(32.28%),available phosphorus(54.50%),alkaline hydrolyzable nitrogen(21.59%),total nitrogen(20.26%),total phosphorus(10.33%).Compared with areca nut monocropping,the intercropping of areca nut significantly reduced soil catalase activity(6.52% lower,the same below),polyphenol oxidase(9.34%),acid phosphatase(10.85%),urease(31.54%);compared with pandan monocropping,the intercropping mode can significantly increase the activities of soil catalase(increase by9.37%,the same below),peroxidase(46.47%)and urease(8.93%),while significantly reduced acid phosphatase content(15.39%)(P<0.05).2.High-throughput sequencing technology was used to analyze the soil microbial community structure of the different planting patterns.The results showed that compared with areca nut monocropping,intercropping management significantly reduced the bacterial Ace index by 6.04% and Chao index by 7.48%,while did not affect Shannon index and Simpson index.There was no significant difference on the diversity index of soil fungal communities among different planting patterns.There were 11 dominant bacterial phyla under different cultivation treatments.The abundance of Proteobacteria,Actinomycetes and Firmicutes were significantly decreased,while the abundance of Chloroflexi,Myxococcus,Methylmirabilota and Gemmatimonadota were significantly increased under intercropping treatment;The dominant phyla of fungi in this study were Ascomycota,Basidiomycota and Rozellomycota,but there was no significant difference on the dominant phylum of fungi among different cultivation modes.In conclusion,the intercropping mode still maintained the relatively stable composition and structure of soil bacterial and fungal communities(P<0.05),although the intercropping mode reduced the Ace and Chao indices of bacterial communities.3.GC-MS technology instrument was used to identify the aroma components of pandan leaves in different cultivation modes.A total of 63 kinds of aroma compounds such as pyrroles,alcohols,phenols,furans,furanones,aldehydes,acids,hydrocarbons,ketones and esters,respectively,were identified in this study.The contents of 2-acetyl-1-pyrroline,phytol,neophytadiene and other substances under intercropping management were significantly higher than those under pandan monocropping treatment,which improved the flavor quality of pandan(P<0.05).There was a close relationship between the types of aroma substances between pandan leaves and soil physicochemical indexes and soil enzyme activities.The contents of acids,aldehydes,hydrocarbons and furans were positively correlated with soil water content(P<0.05);The contents of alcohols were significantly positively correlated with soil available potassium,total phosphorus,alkaline hydrolyzable nitrogen,electrical conductivity,total nitrogen and organic matter(P<0.05);The content of phenols was significantly positively correlated with soil bulk density,p H and peroxidase(P<0.05);The content of ketones and furans was positively correlated with soil catalase,polyphenol oxidase and total potassium;Esters,pyrroles,furans,furanones and hydrocarbons were positively correlated with soil available phosphorus(P<0.05).4.Among the soil microorganisms present in the three cropping patterns of areca nut intercropping with pandan,areca nut monocropping and pandan monocropping,Enterobacter,Lysinibacillus,Arthrobacter and Bacillus were the key bacterial genera affecting 2-acetyl-1-pyrroline,which had a significant positive correlation with 2-acetyl-1-pyrroline(P<0.05).The above results indicated that the intercropping mode is conducive to enhancing the activity of soil enzymes,improving the structure of soil microbial community,and increasing the content of the main aroma components of pandan.The results not only reveal the regulation mechanism to maintain the balance of soil microbial community,but also clarify the key abiotic factors and the action path of soil microorganisms to improve the main aroma components under the intercropping treatment.The conclusion of this study providing a theoretical basis for the optimization and promotion of the cultivation mode of areca nut intercropping pandan,and contribute to the high-quality and sustainable development of related characteristic industries of areca nut and pandan in Hainan.