Concentration-Dependent Effects of Exogenous Glycine Betaine in Alleviating Moderate Salinity Stress in Triticale (×Triticosecale Wittm.)

Crop plants are continuously exposed to adverse environmental conditions, among which soil salinity is one of the major factors limiting plant growth and productivity. One approach to mitigating the detrimental effects of salt stress is the application of osmoprotectants such as glycine betaine (GB), which stabilise cellular structures and protect the photosynthetic apparatus. The aim of this study was to evaluate the effects of glycine betaine (10 and 20 mM) on seed germination and selected physiological parameters of triticale (×Triticosecale Wittm.) subjected to salt stress induced by NaCl (50, 100, and 150 mM). The study consisted of two experiments: a seed germination test conducted in Petri dishes and a pot experiment performed under controlled environmental conditions. In the pot experiment, relative chlorophyll content, chlorophyll fluorescence parameters, and gas exchange characteristics were determined. In the germination assay, salt stress impaired early seedling growth and physiological performance, whereas germination capacity remained unaffected. In the pot experiment, under non-saline stress conditions, application of 10 mM GB significantly increased Fv/Fm in Term I, Fv/Fo in Term II, and E and Ci in both terms (p < 0.05), whereas the increases in relative chlorophyll content and PI were not significant. In the germination test, 10 mM GB increased the number of germinal roots by 20.3% under non-saline conditions and shoot length by 62.9% under 50 mM NaCl (p < 0.05). No significant effect of GB application on shoot dry weight was observed (p > 0.05) in the pot experiment. These results indicate that exogenous application of 10 mM glycine betaine can partially alleviate the adverse effects of moderate salt stress in triticale; however, its effectiveness depends on the severity of salinity and the physiological parameter evaluated.