INITIATION OF THE RHIZOSPHERE EFFECT

Abstract

Microbiological analyses were conducted on unsterilized ground wheat seed, on the emerging primary root, 3 days following planting in soil and at 3-day intervals thereafter for a period of 17 days. By the third day following planting there were more than twice as many bacteria in the rhizosphere soil as in the control soil. Qualitative differences were apparent at this time also in that methylene-blue-reducing bacteria, ammonifiers, denitrifiers, gelatin-liquefying and starch-hydrolyzing types were preferentially stimulated. Studies with individual isolates obtained from samples taken even on the third day showed that rhizosphere population was more active than the soil population in regard to growth rate in different media. All effects mentioned were maintained and in some cases exaggerated with growth of the plant.