Targeting Lucerne Cultivars to Saline-soil Environments

Abstract

Lucerne (Medicago sativa L.) is rated as moderately susceptible to soil salinity, a major stress whose incidence is increasing in drought-prone regions because of irrigation with saline water. Three-year dry-matter yield (DMY) of 14 populations (cultivars or landraces) of different origin was assessed across ten agricultural environments of Algeria, Italy, Morocco and Tunisia whose electrical conductivity (EC_e) in the 0–30 cm soil layer ranged between 0.2 and 6.0 dS m^{− 1}. The adaptive responses of the populations were modeled by factorial regression as a function of EC_e and one or two additional significant covariates. Ameristand 801S (a benchmark variety for salt tolerance) and the Moroccan landrace Erfoud 1 displayed positive genotype × environment (GE) interaction in environments with high soil salinity. Nine populations and one additional Algerian landrace (Tamantit) underwent a seed germination test under saline conditions, to verify the ability of this test to predict the field-based adaptive responses to soil salinity of the populations. The salt concentration required to inhibit germination of 50 % of viable seeds (IC(50)) ranged from 1.13 % NaCl of Prosementi to 2.61 % NaCl of Ameristand 801S. IC(50) values of the populations displayed moderately high correlation (r = 0.70; P < 0.03) with the genotype slope as a function of EC_e in the factorial regression (β EC_e). Salt-tolerant genetic resources could be found in north African landraces which evolved in less favourable oasis environments, such as Tamantit and Erfoud 1.