Pre-sowing magnetic field- induced changes in water relations and lipid peroxidation in cucumber under salinity stress

Overcoming salinity problems through increasing plant tolerance is a substantial strategy to increase crop production. A pot experiment was carried out to investigate the effect of salinity stress, pre-sowing magnetic fields and their combination on cucumber growth, water relations and lipid peroxidation. Seawater salinity (10%) enormously reduced the plant growth, relative water content (RWC), transpiration rate and water use efficiency (WUE), and increased partial osmotic pressure (POP), lipids peroxidation and membrane injury index. Root/shoot ratio was not affected by the salinity stress.
Pre-sowing treatment with 50 mT (for 30 s or 30 min) and 100 mT (30 min) magnetic field enhanced plant growth, root/shoot ratio, RWC, transpiration rate and WUE under control and stress conditions in relation with the un-treated plants. These treatments appeared to reduce lipid peroxidation and membrane injury in cucumber under salinity stress. The effect of these magnetic treatments on POP was not regular. The combination treatment of those magnetic fields and salinity reduced the stress intensity index (SII) by about 25% in relation with salinity alone. Conversely, the application of 200 mT magnetic field for 30 min adversely affected the plant growth and water relations, and increased the SII, lipid peroxidation and membrane injury in cucumber under salinity stress. On many occasions, the effects of 100 mT for 30 min and 200 mT for 30 s were not significant.