Pre-soaking foxtail millet seeds with oligosaccharides enhances germination and seedling growth under PEG-induced osmotic stress

Foxtail millet is a multipurpose crop and is widely cultivated in dry areas of Asia. The aim of this study was to investigate the effect of oligosaccharide priming on foxtail millet seeds during germination under osmotic stress. Germination percentage and seedling shoot and root lengths were not affected by 5% polyethylene glycol (PEG 6000). However, osmotic stress (15% and 25% PEG) dramatically decreased seed germination and other parameters. Under 15% PEG, pre-soaking seeds with low to moderate concentrations (0.1-10 mg L-1) of oligosaccharides had a positive effect on the germination percentage, germination index, shoot length and root length. Thus, the negative effects of osmotic stress on seed germination and seedling growth could be alleviated by oligosaccharide priming treatments, especially at a 1 mg L-1 concentration. These results suggest that oligosaccharides can dramatically improve the osmotic tolerance ability of foxtail millet seeds and seedlings.