Rhizobium strain evaluation of Glycine max cv. Davis, Vigna mungo cv. Regur and V. unguiculata cv. Caloona for three soils in glasshouse and field experiments

Abstract

The need for inoculation of soybean (Glycine max cv. Davis), gram (Vigna mungo cv. Regur) and cowpea (V. unguiculata cv. Caloona) with six appropriate strains of Rhizobium in two grain legume, clay soil growing areas (Narayen and Emerald, central Queensland) and a Rhizobium free (to sparse) soil (Beerwah, in south-eastern Queensland) was investigated in glasshouse and field experiments. Inoculated plants generally had vegetative and grain yields which were between those of the nitrogen and nil nitrogen uninoculated controls, although for the freely nodulating Vigna species the nil nitrogen control plants were sometimes as large as those in the inoculated treatments. The strains of Rhizobium CB1015 and CB1243 performed well on cowpea and gram as did most strains used as inoculum on soybean. Strain USDA94 was often poor on soybean. In the two heavy clay soils tested, plants inoculated with CB756 and the streptomycin-resistant mutant CB756str developed nitrogen deficiency symptoms in their leaves, suggesting that the strains were not suited to those soil types. There was not a close relationship between the glasshouse and field means due to large residual errors in the field.