Drought-tolerant naturalized populations of Lotus tenuis for constrained environments

A perennial forage legume species tolerant to water stress would be useful to improve pasture and animal productivity in the central zone of Chile. The growth, dry-matter (DM) production, and drought tolerance of twelve accessions of Lotus tenuis Waldst Kit, Syn. L. glaber, naturalized in Chile were evaluated with the objective to select contrasting genotypes, tolerant and sensitive to drought, for future breeding programmes. The accessions were sown in pots of 1.3 L containing a volcanic soil (Andisol). A completely randomized design with all combinations of Lotus accessions and four water treatments [100, 70, 40, and 10% of soil water availability (SWA)] was used. The relative rate of stem elongation (RRSE), the shoots and roots DM production, the relative water content (RWC), and the specific leaf area (SLA) were measured. A drought-sensitivity index (DSI) and the interaction genotypexenvironment were calculated. The RRSE, the DM production, RWC, and SLA all showed a significant reduction (P0.05) in the treatment with the higher water restriction (10% SWA). There were significant differences (P0.05) within RRSE and DM production genotype means, but the RWC and SLA did not differ among populations. The DSI varied broadly among genotypes, from 0.49 to 1.34, and was correlated negatively with DM production under water stress (10% SWA). It was concluded that the Lotus tenuis populations showed water-stress tolerance genetic variability, with accessions Lt14 and Lt4 the most contrasting. These findings will permit us to identify chromosomal regions associated with drought-tolerant genotypes which will allow us to accelerate the development of cultivars adapted to water-restricted environments.