Salt stress effects on growth, physiology, and ionic concentrations in hydroponically grown barley genotypes

Soil salinity is a major abiotic stress that severely affects crop production in different regions of the globe. Barley is an essential cereal crop and there is a significant genetic variation among barley varieties for tolerance towards salt stress. Understanding of salinity tolerance mechanisms assists in developing salt tolerant barley varieties in a hydroponics experiment. There were twelve barley varieties and two NaCl stress levels (Control, 100 and 200 mM) in this study. The nursery of barley was seeded in sand and at two-leaf stage; plants were transplanted into hydroponic tubs. The plants were grown under salt stress for 65 days and data regarding several morpho-physiological parameters were collected. The statistical analysis of the collected data was implemented by using completely randomized design (CRD) with factorial arrangement. Exposure to NaCl stress significantly reduced shoot and root growth and relative leaf water contents (RLWC), while increasing Na⁺ concentration, with B-9006 showing the highest root dry weight (0.39 g) and YSM1 recorded the lowest root dry weight (0.10 g) under 100 mM NaCl. The maximum (232 ppm) Na⁺ concentration in leaf sap was observed in variety B-15011 (70 % from control) and minimum was observed in B-15018. Maximum K⁺ mM concentration in leaf sap was found as 72 % in Aia-03 and minimum was observed as 50 % in B-15035. At stress level of 200 mM, highest shoot dry weight (2.52 g) was observed in ZP2 (73 % decreased from control) while minimum shoot dry weight (0.19 g) (96 % decrease from control) was recorded in Franklin genotype. Maximum root dry weight (0.24 g) was observed in B-9006 genotype while minimum root dry weight (0.04 g) was recorded in Gairdner. Maximum K⁺/Na⁺ ratio (1.20) was recorded in B-15018 and minimum (0.14) was seen in B-15035. Therefore, based on our results, barley genotypes can be classified into salt-tolerant (B-9006, B-15018, Yerong, Aia-03), salt-sensitive (Gairdner, Franklin, B-15035, B-05011), and moderately tolerant groups at both 100 and 200 mM NaCl levels.