Physiological Changes and Subsequent Recovery in Seedlings of Two Lines of Oat (Avena nuda L.) in Response to Salinity

Breeding elite cultivars with high salinity tolerance and recoverability is an important target for crop breeders. Evidence for recoverability from salinity for oat (Avena nuda L.) is scarce. Here, we assessed the physiological response of two oat lines (Bayou1 and Yanke1) during salinity exposure and recovery. The lines were treated with different NaCl concentrations [by gradually increasing the concentration from 50 mM (day 0) to 100 mM and then to 200 mM and 300 mM (day 15)] in 5-day intervals, followed by a recovery period of 20 days. In both oat lines, salinity inhibited plant growth, K+ acquisition, leaf water uptake, and leaf Ca2+ and Mg2+ concentrations. Salinity also inhibited the Mg2+, K+, sugar, and total amino acid contributions to leaf osmotic potential and increased Na+ accumulation. After the recovery period, the increased K+ acquisition and reduced Na+ accumulation demonstrated the resilience of cellular ionic homeostasis in all organs. The increased leaf osmotic potential indicated the resilience of water uptake ability in both lines. Recovery from salinity was also indicated by increased leaf Ca2+ and Mg2+ concentrations. The resilience of beneficial osmolyte (Mg2+, K+, sugar, and total amino acid) contributions to leaf osmotic potential suggested the resilience of cell extension ability. The capacity of oat seedlings to recover from salinity was related to detoxification of Na+, resilience of ionic homeostasis, and osmolyte production in the leaves. This research could provide useful physiological information related to salt tolerance and recovery capacity of oats.