A Negative Feedback Regulation of Replanted Soil Microorganisms on Plant Growth and Soil Properties of Peach

Abstract

Replant disease is one of the main growth limiting factors, interfering with plant growth and yield of stone fruit trees such as peach trees. The ecological feedback mechanisms by replanted soil microbes regulating peach growth and soil structure are rarely known. In our study, rhizosphere soils collected from 18-year-old peach trees were used to plant new peach seedlings, and all soil microbes (R) and soil microbes with the size of < 100 mu m (R-<100) and < 40 mu m (R-<40) were applied into peach rhizosphere. After 90 days of microbial inoculation, compared with no microbe treatment (R-0), the treatments such as R, R-<40, and R-<100 reduced plant growth performance (biomass, leaf number, plant height, and stem diameter) and root morphology (total length, projected area, surface area, diameter, and volume), with treatment R being the most inhibition of all other treatments. Similar response of treatment R was observed on changes in concentrations of chlorophyll a, chlorophyll b, and carotenoid. Interestingly, compared with R-0 treatment, R-<100 treatment produced a significant increase in glomalin-related soil protein (GRSP), percentage of water-stable aggregates in size of 0.25-0.5 mm, soil polyphenol oxidase activities and soil catalase activities. However, R treatment dramatically decreased the percentage of water-stable aggregates in size of 2-4 mm and soil peroxidase activities. Our results suggested that replanted soil microbes, especially with the size of < 100 mu m, played a strong negative role on plant growth and rhizosphere biology of peach.