Deciphering soil microbiome to investigate the effects of sod culture on pomelo orchards in Madou Tainan

Abstract

Sod culture is an environmental approach frequently applied in orchards to lessen the chemical damages caused by conventional intensive agriculture The management increases soil organic matters and moisture but the effects on soil microbiome are still largely unknown Hence I utilized targeted metagenomics to investigate the soil microbiome in eight sod culture (S) orchards and six clean tillage (CT) orchards in Madou at two time points before flowering and before harvest In both types of orchards Proteobacteria Acidobacteria and Actinobacteria were the predominant bacteria across time points At genus level Streptomyces and Nocardioides were enriched in S orchards while Pseudomonas revealed significantly high abundance in CT orchards Interestingly soil microbial communities showed strong correlation with soil chemical properties only in CT orchards Such effect may also reduce microbial diversity when the supply of nitrogen is limited before harvest On the contrary S orchards stabilized soil microbial communities by maintaining species diversity and showed a convergence pattern during the nutrient-depletion period As a result microbial communities in S orchards were less affected by agricultural manipulation compared to CT orchards Besides co-occurrence network reveals higher modularity index in S orchards while the microbiome in CT orchards formed a giant module probably due to high dependence to the pomelo tree under low plant diversity In conclusion although the microbial community was not drastically changed by sod culture a positive network between trees and environment was nevertheless strengthened via land cover with native vegetation

Date of Award	2020
Original language	English
Supervisor	Chao-Li Huang (Supervisor)