ALLEVIATION OF WATER STRESS AND PROMOTION OF THE GROWTH OF SUGAR BEET (BETA VULGARIS L.) PLANTS BY MULTI-TRAITS RHIZOBACTERIA

Drought stress may affect the yield and sucrose accumulation of sugar beet by restricting leaf and root growth. The effect of inoculation of nine IAA-producing, N-2-fixing, P-solubilizing and ACC deaminase-containing bacteria on the yield and morpho-physiological parameters of sugar beet under five different water regimes was investigated. The diminishing water supply caused a gradual decrease in the plant growth, chlorophyll contents, root and leaf weight and sugar content, accompanied by increasing activities of drought stress markers (GR, GST, G6PD, 6PGD, MDA and H2O2). Although it varied depending on the water regimes and bacterial strains, the results of two pot experiments show that inoculation with multi-traits plant growth promoting bacteria stimulated overall plant growth, including enzyme activity, sugar content, fibrous and storage roots development and leaf yield and the contents of leaf chlorophyll, N, P, K, Ca, Mg, Na, Mn and Zn, but decreased MDA and H2O2 contents, which might partly contribute to the activation of the processes involved in the alleviation of the effect of water stress.