Effects of biochar on the growth of apple seedlings, soil enzyme activities and fungal communities in replant disease soil

Apple replant disease (ARD) is a soil-borne disease that negatively effacts tree growth and reduces the yields in replanted orchards. We aimed to determine whether the addition of biochar to replant soil could promote plant growth by improving the soil environment. Biochar was added to apple replant soil at 0, 5, 20, or 80 g kg−1, and its effects on Malus hupehensis Rehd. seedling growth and on the soil environment were determined. Biochar significantly increased seedling height, dry weight, root length, root volume, and respiration rate. Biochar increased the activities of soil enzymes (invertase, urease, proteinase, neutral phosphatase, catalase, and polyphenol oxidase). The terminal restriction fragment length polymorphism (T-RFLP) profiles of fungal communities differed between the 80 g kg-1 biochar treatment and the other treatments. Shannon’s diversity index was highest in the 80 g kg-1 biochar treatment. Biochar decreased the abundance of the soil-borne pathogen Fusarium solani. These effects resulted in enhanced plant growth.