[Study of the nature of the associated microflora in the prolonged substrateless cultivation of beet plants].

The purpose of the present investigation was to study variations in the population density of microorganisms, their qualitative and quantitative composition during substrate-free cultivation of beats. The results obtained show that the microbial number in the nutrient solution increased by the time of intensive growth of beats and decreased by the time of harvesting. The number of root microorganisms was much greater than the total number of microorganisms in the nutrient solution. Oligonitrophils and nitrogen fixing bacteria were found in the solution. This may be associated with a transient decrease of nitrogen in the solution. The number of ammonifiers and denitrifiers in the solution increased significantly by the end of plant vegetation; the amount of denitrifiers inhabiting the roots decreased during vegetation and that of ammonifiers increased. In the middle of vegetation cellulose decomposing aerobes appeared; this might occur since root hairs began to die off. By the end of vegetation an insignificant amount of fungi was also found. Nitrifying and spore-forming microorganisms were not detected. The identification of predominant microbial species showed them to be bacteria of the genera Pseudomonas and Mycobacterium. Besides, microorganisms of the genera Bacterium, Micrococcus, Mycococcus, Chromobacterium and Pseudobacterium also occurred.