Ammonium bicarbonate alleviates apple replant disease: Inhibiting Fusarium and improving soil environment

Providing nitrogen is the core of increasing production in modern agricultural systems, as well as in the production of fruit trees. The rational application of nitrogen is an important measure to increase production and sustainably utilize agricultural ecosystems. Greenhouse, pot and field experiments were conducted to study the effects of different nitrogen forms on the antifungal effect in vitro, apple growth status and the soil environment under replant condition, aims to provide a basis for scientific fertilization and alleviates apple replant disease during orchard construction. We investigated the growth of apple in replant soil treated with different forms of nitrogen, including ammonium nitrogen (NH4N), nitrate nitrogen (NO3N) and amide nitrogen (CO(NH2)2). The results showed that ammonium bicarbonate can inhibit the mycelial growth, spore germination and toxins synthesis of soil-borne pathogens in vitro. The addition of ammonium bicarbonate significantly promoted the replanted apple growth. The activities of soil sucrase, urease, phosphatase and catalase were higher following treatment with ammonium bicarbonate than in the control soil. The qPCR analysis showed that the bacterial, fungal biomass differed distinctly between the different nitrogen forms and the control. These results suggest that ammonium bicarbonate can inhibit the mycelial growth, spore germination and toxins synthesis of soil-borne pathogens, improve the activities of soil enzymes and change soil microbial biomass. These changes can promote growth ofreplanted apple, thereby, ammonium bicarbonate can be used to alleviate apple replant disease as a new control measure.