NODULATION FAILURE IS IMPORTANT IN THE POOR GROWTH OF 2 LUPIN SPECIESON AN ALKALINE SOIL

This study examined the effects of inoculation of Bradyrhizobium sp. ( Lupinus) on the nodulation and growth of 2 lupin species on an alkalin e soil in the field. Plants of L. angustifolius cv. Gungurru (alkaline -sensitive) and L. pilosus Murr. P23030 (alkaline-tolerant) were eithe r not inoculated or inoculated with Bradyrhizobium (strain WU425 or WS M1253) and grown on an alkaline clay, an acid loam, and a limed acid l oam. On the alkaline soil, plants of both lupin species without inocul ation nodulated poorly and had low nitrogen (N) concentrations in shoo ts. Inoculation with bradyrhizobia on the alkaline soil greatly increa sed nodulation and N concentrations in shoots, but nodule number of L. angustifolius was still lower than that on the acid soil. Lupin speci es differed in growth and nodulation on the alkaline soil, L. pilosus being more tolerant than L. angustifolius. Effects of liming on growth and nodulation were not significant. A survey of a farmer's crop of L . albus cv. Kiev mutant, adjacent to the field trial, showed that poor growth was associated with high soil pH and poor nodulation.