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Phosphorus (P)‐deficiency symptoms are known for Lupinus species grown in calcareous soil, but we do not know if this is due to high calcium (Ca) availability or low P availability in the soil. To address this problem, we explored both the effects of Ca and its interaction with P on nutrient status and growth of three Lupinus species. Two Ca‐sensitive genotypes ( Lupinus angustifolius L. P26723 and Lupinus cosentinii Guss. P27225) and two Ca‐tolerant genotypes ( L. angustifolius L. cv Mandelup and Lupinus pilosus Murr. P27440) were grown hydroponically at two P (0.1 and 10 μM) and three Ca (0.1, 0.6 and 6 mM) levels. Leaf symptoms and biomass were recorded, whole leaf and root nutrient concentrations were analysed, and leaf cellular P and Ca concentrations were determined. Phosphorus‐deficiency symptoms were only observed in the Ca‐sensitive genotypes. Among all the genotypes in this study, the Ca‐tolerant L. pilosus showed an ability to maintain stable leaf Ca and P concentrations whereas the Ca‐tolerant L. angustifolius cv Mandelup did not maintain a stable whole leaf Ca concentration, but maintained a low cytosolic Ca 2+ concentration through effective Ca compartmentation. However, the two Ca‐sensitive genotypes, L. angustifolius P26723 and L. cosentinii , did not exhibit an ability to maintain a stable whole leaf Ca concentration or effectively compartmentalize Ca. Therefore, having the capacity to maintain a stable whole leaf Ca concentration or effectively compartmentalizing Ca in leaves are likely critical for Lupinus species to be Ca tolerant.
Ding et al. (Fri,) studied this question.