Assessment of resistance to PEG-induced drought in annual medic using aquaculture conditions

Annual medics (Medicago spp.) are suitable plant species for cultivation in regions with soil erosion problem, and due to limited water resources in such areas, drought resistance in these species is considered a valuable trait. Nine populations, of five annual medic species were assessed for drought resistance under aquaculture condition. Different levels of polyethylene glycol (PEG) were employed to induce drought stress Physiological/biochemical traits including germination rate, leaf vigor, root length, shoot height, free proline content, and total soluble sugars were recorded. Results confirmed the significant effects of PEG on drought stress induction, and biochemical traits showed higher correlation with drought level compared to phenotypical ones. It is postulated that while sugar accumulation is started at low stages of drought, proline accumulation will initiate at critical drought levels. While M. truncatula expressed higher levels of biochemical traits, M. orbicularis showed superior in terms of phenotypic characteristics. The results suggested that the drought resistance gained by proline accumulation capability might have emerged in annual medic during the long-term biodiversity procedure.