Variation in the growth of lupin species and genotypes on alkaline soil

Commercial lupins grow poorly on alkaline and neutral fine-textured soils. Genotypic variation exists among lupins. The present study compared the growth of 13 lupin genotypes, including introduced cultivars and wild types, in an alkaline loamy soil and an acid loamy soil.Plants grown in the alkaline and acid soils did not show obvious symptoms of iron deficiency at any stage. There was however a large variation of shoot fresh weight among genotypes in response to the alkaline soil with L. atlanticus and L. pilosus being more tolerant than L. luteus, L. cosentinii, L. albus and L. angustifolius. Some variation also existed among genotypes of L. angustifolius. In addition, root growth was retarded on the alkaline soil except for L. atlanticus, L. pilosus P20955 and L. albus Kiev mutant. In the alkaline soil, root growth at week 2 correlated well with the shoot fresh weight at week 12. The results suggest that early root elongation may be useful for screening tolerant genotypes for alkaline soils.