Specific and genotypic variation in the nutrient content of lupin species in soils of neutral and alkaline pH

Abstract

Evaluation of the nutritional status, dry weights, and yields of genotypes of white lupin (Lupinus albus L.) and of the species L. pilosus Murr. and L. angustifolius L. were made in a field of mildly acidic (minimum pH 5.8; air-dried soil : water ratio 1 : 2.5) to alkaline (limed to a pH maximum of 8.4) soil at IACR-Rothamsted, UK, during the 1997 growing season. Plants were sampled for shoot biomass and nutritional content during the season and seed yield per plant.

Lupinus pilosus was the species most tolerant of the calcareous soil, whereas L. angustifolius was the least tolerant. Considerable variation in tolerance was apparent between the L. albus genotypes; the cultivar Lucyanne was comparable with L. angustifolius, whereas the genotypes La 673, 668, and 675 were more comparable with L. pilosus.

Leaf chlorosis was shown to be an unreliable measure of calcareous soil tolerance in the field. A genotype soil-pH interaction in the expanded leaf number indicated that this analysis might be of use in genotype evaluations. Nutrient concentration differences were apparent between the species and between the L. albus genotypes. This indicated the occurrence of possible tolerance mechanisms including the control of calcium uptake and the partitioning of iron. Clear differences were apparent between the three species in terms of tolerance to the calcareous soil. Within L. albus important differences were apparent when specific analyses were examined. However, variation between different analyses and at different stages of growth resulted in the differences, taken as a whole between the L. albus genotypes, not being of sufficient magnitude to discriminate potentially tolerant from susceptible genotypes. The complexity of calcareous soil stress and the potential application of the analyses for physiological studies and genotype screening are discussed.