EFFECT OF VARIETY AND ENVIRONMENTAL-FACTO RS ON THE PHYTO-EFFECTIVITYOF BACTERIAL INOCULATIONS IN PEAS

Of 171 strains of Rhizobium leguminosarum, three strains repeatedly ca used increased pea yields in pot and field experiments. A combined ino culation with all three strains did not give better results than singl e inoculations. However, a positive effect was found when combining th e strains with a strain of not host-specific, phytohormone forming Rhi zobium. The effects of the inoculation are specific for the variety, b ut not for the growth type. After inoculation with effective Rhizobium -strains, most varieties showed increased length and branching of root s, dry matter of roots and shoots and seed yield. One variety showed a negative reaction on the inoculation. Optimal plant development and p hotosynthetic efficiency are important prerequisites for positive effe cts of the inoculation. They can be varied by light intensity, soil hu midity and temperature. Due to an increased infestation with soil born e plant pathogens and stronger water stress, the certainty of a contin uous effect until maturity is lower under field conditions on loamy sa nd than on loess soils.