The Effects of Bioinoculants Based on Mycorrhizal and Trichoderma spp. Fungi in an Apple Tree Nursery under Replantation Conditions

Abstract

Both mycorrhizal and Trichoderma spp. fungi are known for antagonistic effects against certain biological pathogens causing apple replant disease (ARD). The aim of this study was to assess the effectiveness of the bioinoculants based on endomycorrhizal and Trichoderma spp. fungi on the biological properties of soil as well as the parameters of the apple tree growths in a fruit tree nursery under replantation conditions. A two-year experiment was conducted on Jonagold apple trees grafted on to M.9 rootstock in western Poland. The trees were planted in the replant soil—from areas used for the production of apple trees, and in the crop rotation soil, that had not been used for nursery purposes before. A mycorrhizal inoculum and preparations containing Trichoderma spp. fungi were applied to the replant soil. Biological properties of the soil and the growth of the aerial and underground parts of the apple trees were assessed. The enzymatic (dehydrogenases and protease) and respiratory activity of the replant soil was significantly lower than that of the crop rotation soil. The apple trees grew worse when exposed to the ARD conditions. The effectiveness of applied bioinoculants in mitigating the effects of replantation in the nursery were shown. Both the treatment mycorrhization and the application of bioinoculants containing Trichoderma spp. increased the respiratory and enzymatic activity of the replant soil. The growth of the root system and the aerial parts of the trees (including leaves) was much better after the combined use of both types of fungi than in the replant soil that had not received the fungal treatment.