Ranking 26 European hemp (Cannabis sativa L.) cultivars for osmotic stress tolerance and transpiration efficiency

Hemp (Cannabis sativa L.) is a multi-purpose industrial species, which is valued as a low-input crop suited to marginal environments. However, research on the water stress resistance and water use efficiency of hemp cultivars is scarce. Three lab-scale experiments were carried out to test 26 commercial European hemp cultivars under osmotic stress at germination (experiment 1) and on plantlets at vegetative stage (experiment 2); and to calculate transpiration efficiency (TE) under well-watered conditions (experiment 3). Eight parameters were analysed: maximum germination percentage, lag time and germination homogeneity in experiment 1; maximum quantum yield of PSII (Fv/Fm), performance index, relative water content and proline content in experiment 2; TE in experiment 3. Osmotic stress application significantly affected all parameters in experiments 1 and 2, and responses to water stress differed significantly among cultivars for all parameters, except proline content. Considering all parameters except proline content, a principal component analysis was carried out for ranking the cultivars. The cultivars 'Carmaleonte', 'Codimono', 'Futura 75' and Santhica '70' ranked the highest, while cultivars 'Bialobrzeskie', 'Ermes' and 'Finola' had the worst performances for all traits.