SEASONAL VARIATION IN THE COMPOSITION OF THE BACTERIAL SOIL FLORA IN RELATION TO PLANT DEVELOPMENT

Abstract

In field experiments with oats the composition of the bacterial population in the rhizosphere was found to be almost stable during the whole period of plant development from young seedlings to maturity. In the beginning of the growth season the soil flora was quite different from that of the rhizosphere. It was, however, successively changed, and became, toward the end of the season, similar in composition to the rhizosphere population. This change proceeded from the soil surface into deeper soil layers, and it can be concluded that it was due to the development of roots, and to a migration of bacteria from the rhizosphere into the soil.