THE INFLUENCE OF ZINC-CONTAINING FERTILIZERS ON THE MICROBIAL COMPLEX OF TEA PLANT (<i>СAMELLIA SINENSIS </i>L.) RHIZOSPHERE IN THE CONDITIONS OF RUSSIAN SUBTROPICAL ZONE
The paper studies the influence of zinc-containing fertilizers on the number of the basic physiological groups of tea plant rhizosphere microbial complex (bacteria, fungi, actinomycetes). As a research zone we took brown forest acid soil in Russian humid subtropics on the Black Sea coast. The number of microorganisms during the study period varied depending on hydrothermal conditions, plant growth phase and microbial resistance to the zinc-containing fertilizers. The dominant group of microorganisms were saprophytic bacteria, the number of meat-peptone agar was from0,4 × 106 to 5,1 × 106 colony forming units/g of abs. dry soil. The number of fungi and actinomycetes was by 1-3 orders of magnitude lower - from 2,0 × 103 to 1,3 ×105 colony forming units/g of abs. dry soil. At this stage of the studies it was found that the use of zinc sulfate at a dose of 4,3 kg of active ingredient / ha in the background fertilizers (N240P70K90 kg ai/ha) in brown forest acid soils of tea plantation led to a significant reduction in the number of prokaryotic microorganisms (bacteria on meat-peptone agar on average 2,4 times and actinomycetes on average 5 times). The influence of zinc-containing fertilizers on the number of fungi (eukaryotes) was slight. Thus, the ratio of the basic physiological groups of microorganisms in tea plant rhizosphere changed, reducing the share of the bacteria (on meat-peptone agar and actinomycetes) with a corresponding increase in the share of fungi.