Effects of salicylic acid on salinity tolerance of wheat (Triticum aestivum)

Four glasshouse experiments examined salinity stress and tolerance in wheat. The first experiment examined the responses of three wheat cultivars from Saudi Arabia (Local wheat, West bread and Yecora Rojo) and two UK wheat cultivars (Paragon and Belvoir) to different levels of salinity (Tap water, 25, 50, 100, 150 and 200 mM NaCI). In the second experiment, Yecora Rojo and Paragon were selected to test whether improved wheat tolerance to salinity could be obtained by applying exogenous Salicylic acid (0, 0.5, 1 and 2 mM SA) via priming seeds for 6 hours. The third experiment further tested the effect of SA on tolerance to salinity with SA applied through seed soaking for 6h and 24h. Two salinity tolerant cultivars (S24 and Sakha 93) were included for comparison. The fourth experiment compared the effect of SA applied by seed soaking (6h) or by foliar spray. In all experiments, saline conditions gave significant declines in wheat growth parameters, gas exchange, yield and yield components with increases in salinity concentration, whereas protein and chlorophyll content increased. Cultivar Paragon grew significantly better than cultivar Yecora Rojo in non-saline conditions but not under salinity stress. Treating wheat with SA produced only a minor improvement in growth parameters, yield and yield components under salinity stress. Compared to salt tolerant cultivars, Paragon showed significant response to SA in most variables. The influence of SA depended on genotype, plant stage and SA concentration more than soaking time and application method with 0.5 and 1 mM SA concentrations being the most effective. SA mitigates but does not prevent salinity impacts and has a dual function which can give positive or negative effects under salinity stress.EThOS - Electronic Theses Online ServiceGBUnited Kingdo