Plant-microbial interactions as a way of increasing the efficiency of Spiraea cantoniensis Lour. growing in an industrial nursery

Cultivation of propagation material requires the application of high doses of mineral fertilizers. This often leads to environmental pollution. One of the ways to increase the efficiency of seedlings and cuttings growing is the use of microbial preparations (MP) provided the preservation of environment and the improved soil fertility. MP are created on the basis of active strains of microorganisms possessing useful properties. They affect plants in a complex way: improving nutrition through nitrogen fixation and phosphate mobilization, stimulating growth, and protecting against pathogens. The use of such preparations in an ornamental nursery is limited. Our study included the following MP: Phosphoenterine (PMB) – Enterobacter nimipressuralis-32-3, phosphate mobilizer, growth stimulator; Azotobacterine (AB) – (Azotobacter chroococcum 10702) – nitrogen fixator, bioprotector, growth stimulator; Complex of microbial preparations (CMP), a mixture of AB + PMB + Biopoliticide (Bacillus polymyxa P) – antagonist of pathogenic microbiota, phosphate mobilizer. The experiment was conducted on lignified cuttings of Spirea cantoniensis. A three-year study showed that use of MP increased the survival of lignified cuttings, improved their growth, promoted the formation of lateral shoots and increased the output of standard cuttings by 13-46%. The low rhizogenesis of cuttings of S. cantoniensis during cultivation in an open ground nursery is caused by a lack of atmospheric moisture in April. The use of AB during of S. cantoniensis cuttings growing in the nursery led to an increase in the content of N-NO₃ and mobile K₂O in the soil, N and K₂O in leaves, but decreased the content of mobile P₂O₅ and the total P₂O₅ in leaves. We recommend using of MB for the cultivation of S. cantoniensis cuttings with the introduction of starting phosphorus doses (P_20-30) during the planting, the maintenance of optimum soil moisture in April-May, as well as the introduction of organic matter in the steam field, which lead to better bacterial development and an increase in humus content.