Comparison of acid and alkaline soil and liquid culture growth systems forstudies of shoot and root characteristics of white lupin (Lupinus albus L.) genotypes

Current agronomic cultivars of white lupin (Lupinus albus L.) in the Europe an Union are intolerant of calcareous soils, producing poor yields. Intoler ant genotypes of L. albus, and a tolerant genotype of L. pilosus Murr. were grown in liquid culture varied for pH, or pot and chamber soil systems var ied for lime. Chlorosis, determined visually as leaf interveinal yellowing, was shown to be an unsuitable genotype screen. However, leaf greenness mea sured electronically at a sub-chlorotic level, provided a quantifiable esti mate of stress. Shoot Ca concentration increased when plants were grown in the limed compared with non-limed soil, but remained unchanged between the liquid culture treatments. The root systems in the pots and liquid culture showed growth abnormalities, whereas important differences between L. albus and L. pilosus root systems were seen in the soil chambers. The tap and la teral root dry weights of both species were lower in the limed soil than in the non-limed soil. The dry weight per plant of the cluster roots was comp arable between the treatments in both species, although when grown in the l imed soil they accounted for a larger proportion of the L. albus root syste m. In contrast, the proportion of the root system that was cluster root in L. pilosus was comparable between the treatments. In limed soil, both speci es showed increased levels of extractable citrate from the soil adhering to the cluster roots compared with that in the acid-pH soil. However this did not result in higher shoot P concentrations in the limed compared with aci d-soil grown plants. These results demonstrated the importance of analysing a developed and unrestricted root system when determining the physiologica l responses of these species to limed soil.