The effects of organic matter on the physiological features of Malus hupehensis seedlings and soil properties under replant conditions

Two fermentation methods, aerobic (generating solid compost) and anaerobic fermentation (generating fermented fluid), were adopted to treat the same amount of organic matter to generate solid compost and fermented fluid, respectively. These treatments were used to supplement replant soils in a pot, respectively, where Malus hupehensis Rehd. seedling was replanted. The pilot project was aimed at investigating the influence of organic matter applied to soil on the physiological features of the plant as well as its impact on soil properties. The following four treatments were adopted in the study: new cropping soil, replant soil, replant soil with solid compost, and replant soil with fermented fluid. The growth of seedlings in the four soils was monitored by biomass production and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in the plant roots. The activities of soil urease, soil invertase, and soil phosphatase were measured: and the bacterial, fungal, and actinomycetal contents in the soils were also measured. This study showed that the supplementation of organic matter in a fermented liquid form to replant soil significantly enhanced the biomass production of the seedlings compared to the solid compost form. The activities of SOD. POD, and CAT in the roots were increased by both forms of organic matter, with the solid compost form having a stronger effect than the fermented liquid form. Moreover, both forms increased the activities of soil urease, soil invertase, and soil phosphatase, with the fermented liquid form having a stronger impact than the solid compost form. The addition of organic matter in the form of fermented fluid to the replant soil obviously increased the bacteria content in the soil in comparison with the addition of organic matter in the form of solid compost. Compared to the solid compost, the fermented fluid led to a higher increase in the fungal and actinomycetal contents in the soil at the early stage but a lower increase at the late stage. When applied to replant soil, the fermented fluid form of organic matter was superior to the solid compost form of organic matter in preventing apple replant disease (ARD). (C) 2012 Elsevier B.V. All rights reserved.