PLANT-GROWTH STIMULATION BY INOCULATION WITH SYMBIOTIC AND ASSOCIATIVE RHIZOSPHERE MICROORGANISMS

Selected Rhizobium bacteria, arbuscular mycorrhiza-forming (AM) fungi and associative bacteria have been shown to stimulate the growth of le gumes, gramineae and cruciferae in field experiments on different soil types in temperate regions. A combination of microorganisms with diff erent metabolic capacities (N-2-fixation, P-mobilization; production o f phytohormones and antibiotics) can partly surpass the effect of sing le inoculations, or can produce a positive effect where single inocula tions are ineffective. Growth stimulation by inoculation requires micr oorganisms with phytoeffective metabolic characteristics and the abili ty to survive in the rhizosphere during the growth period. Another pre requisite is an adequate supply of plant assimilates for the productio n of microbial phytoeffective metabolites. Type of inoculum, method of inoculation and agricultural measures can influence the effect of the inoculation. Research is necessary to extend our knowledge both of ba sic principles, and about using microorganisms in practice.