Annals of Botany 89: 341-349, 2002
© 2002 Annals of Botany Company
The Development of Potential Screens Based on Shoot Calcium and Iron Concentrations for the Evaluation of Tolerance in Egyptian Genotypes of White Lupin (Lupinus albus L.) to Limed Soils
1IACR-Rothamsted, Harpenden, Hertfordshire, AL5 2JQ, UK, 2Department of Agricultural Sciences, The Royal Veterinary and Agricultural University, Thorvaldsenvej 40, DK-1871 Frederiksberg C, Denmark, 3INRA, Unite Genetique et Amélioration des Plantes Fourragères, 86600 Lusignan, France and 4Südwestdeutche Saatzucht, Im Rheinfeld 1–13, D-76437 Rastatt, Germany
* For correspondence. Fax +44 (0) 1582 760981, e-mail simon.kerley{at}bbsrc.ac.uk
Received: 23 July 2001; Returned for revision: 6 November 2001; Accepted: 4 December 2001.
European cultivars of white lupin (Lupinus albus L.) grow poorly in limed or calcareous soils. However, Egyptian genotypes are grown successfully in highly calcareous soil and show no stress symptoms. To examine their physiological responses to alkaline soil and develop potential screens for tolerance, three experiments were conducted in limed and non-limed (neutral pH) soil. Measurements included net CO2 uptake, and the partitioning of Fe2+ and Fe3+ and soluble and insoluble Ca in stem and leaf tissue. Intolerant plants showed clear symptoms of stress, whereas stress in the Egyptian genotypes and in L. pilosus Murr. (a tolerant species) was less marked. Only the intolerant plants became chlorotic and this contributed to their reduced net CO2 uptake in the limed soil. In contrast, Egyptian genotypes and L. pilosus showed no change in net CO2 uptake between the soils. The partitioning of Ca and Fe either resulted from the stress responses, or was itself a stress response. L. pilosus and some Egyptian genotypes differed in soluble Ca concentrations compared with the intolerant cultivars, although no significant difference was apparent in the Ca partitioning of the Egyptian genotype Giza1. In a limed soil, Giza1 maintained its stem Fe3+ concentration at a level comparable with that of plants grown in non-limed soil, whereas stem [Fe3+] of an intolerant genotype increased. Giza1 increased the percentage of plant Fe that was Fe2+ in its leaf tissue under these conditions; that of the intolerant genotype was reduced. The potential tolerance of the Egyptian genotypes through these mechanisms and the possibility of nutritional-based screens are discussed.
Key words: Lupinus albus, white lupin, Lupinus pilosus, limed soil, calcium, iron, photosynthesis.