Analytical Interpretation of the Beneficial Interaction Between Microorganisms and Grasses

Abstract

Soil microorganisms compose ¼ of the biodiversity of our planet and are responsible for important processes such as the decomposition of organic residues and the transformation of the nutrients contained in these residues into nutrients for plants. The microorganisms also aid the grasses implantation, increasing the grasses yield by means of several mechanisms of plant growth promotion. These mechanisms of growth promotion of grasses can be direct, or indirect. In this chapter, we discuss the main mechanisms of growth promotion of grasses by soil microorganisms. It will be explained how the microorganisms in the soil act favoring the growth and development of cultivated grasses. For this, there will be clariied the importance of soil microorganisms in nutrient cycling, the mechanisms of nutrient capture, the production of phytostimulant substances by microorganisms, and the mechanisms of soil pathogen suppression.Keywords: nutrient cycling, biological nitrogen ixation, interaction between plants, microorganisms IntroductionThe microbial population inhabiting the rhizosphere consists of a wide range of organisms, which together interact directly and indirectly with the cultivated plants. Only with regard to the number of bacteria, it is estimated that there are about 2 billion cells per gram of soil [1]. These microorganisms become interesting to the human species, as they interfere in the yield of the cultivated plants, by means of several mechanisms.A microorganism is considered a plant growth promoter when it is capable of increasing the yield of the crops of interest. To measure this capacity, the interaction of a given microorganism with some plants of interest must irst be evaluated under axenic conditions and in comparison © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.with cultivated plants. It is fundamental that this initial stage is studied in isolation of the interaction of the plant with the organism, thus isolating the interaction of other factors such as climate, environment, and other edaphic or epiedaphic macro or microorganisms to make sure that the efect on the yield of the plants of interest is solely and exclusively due to the inoculated microorganism. Without this initial screening under axenic conditions, it would be impossible to certify and prove that the positive efect observed in the studied plant is due to the microorganism of interest.Only after the positive efect of the microorganism on the plant has been proven, this interaction will be tested under conditions of greater interference, such as greenhouse, fertilization, or soil conditions with an original ield microbial population (nonsterile soil). Under these conditions, the resistance of the interaction to various interference factors will be tested. Once approved in tests condu...