Survival of plant growth promoting rhizosphere bacteria in the rhizosphere of different crops and migration to non-inoculated plants under field conditions in north-east Germany

Abstract

Survival of two plant-growth-promoting bacteria, Pseudomonas fluorescens PsIA12 and Rhizobium trifolii R39 (rifampicin-resistant mutants), was studied in the rhizosphere of different crops in field experiments on loamy sand in the years 1993 and 1994 (Müncheberg, Germany). After seed inoculation with a peat formulation the Rhizobium strain colonized the rhizosphere of pea and white lupin as well as that of the non-legumes maize, wheat and rape. While the Rhizobium strain established more or less stable populations during the whole vegetation time, the population of the Pseudomonas strain increased with the vegetative plant development and declined with flowering and maturing of the legumes. In the maize rhizosphere this strain was reisolated only in numbers lower log 3 cfu · g root -1. Both strains were able to establish small populations up to log 4.8 cfu · g root -1 in the rhizosphere of non-inoculated crops and weeds up to 0.6 m away from inoculated plants.