Effect of Microbial Inoculants on the Yield of English Ryegrass, And Number and Diversity of Rhizospheric Microorganisms

Plant growth promoting rhizobacteria (PGPR) have originally been defined as root-colonizing bacteria that cause either plant growth promotion or biological control of plant diseases. The mechanisms by which PGPR promote plant growth are not fully understood, but it is believed that the plant growth promoting rhizobacteria enhance plant growth and yield either by direct or indirect mechanisms. Treatment with PGPR has increased the germination percentage, seedling vigor, plant stand, root growth, shoot growth, total biomass of plants, seed weight, early flowering, increased grain, fodder, fruit yields and stimulated plants to grow faster and greener with longer roots and shoots than the untreated plants. Different bacteria that have been reported as PGPR belong to the following genera: Pseudomonas, Bacillus, Azospirillum, Agrobacterium, Azotobacter, Arthrobacter, Alcaligenes, Serratia, Rhizobium, Enterobacter, Beijerinckia, Klebsiella, Clostridium, Streptomyces, Trichoderma Variovovax, Xanthomonas and Phyllobacterium. The positive results of the use of microorganisms in the production of field and vegetable crops, as well as in the production of forage legumes, justify the assumption that they can successfully be used in the production of forage grasses, too. This paper presents the effects of microorganisms on the growth and yield of forage grasses (mainly English ryegrass) as well as on the change in the microbiological activity in the rhizosphere of these plants. There has not been much research in this field so the aim of the investigation was to stimulate interest in the introduction of new agrotechnical measures in the production of plants which are usually considered less important than alfalfa, clover or fodder peas.