Enhancing Grape Seed Germination and Seedling Development Through Varietal Responses to Sodium Nitroprusside and Gibberellic Acid Applications

Germination ability and seedling development of grape (<i>Vitis vinifera</i> L.) seeds show significant differences depending on cultivar characteristics and germination conditions, and this situation is known to create significant difficulties in grape breeding programs and vegetative propagation. In this study, we explored the effects of different concentrations of sodium nitroprusside (SNP; 500–3000 ppm) and gibberellic acid (GA₃) on seed germination and seedling growth in several grape cultivars. Our findings show that cultivar, treatment type, and their interaction had significant effects on both germination and growth. The 5 BB rootstock stood out with consistently high germination rates, reaching up to 95% with 1500 ppm SNP. Overall, SNP treatments outperformed both the control and GA₃ applications, although the most effective concentration differed by cultivar. The most beneficial SNP doses ranged between 1000 and 3000 ppm, with 1500 ppm yielding the highest improvement, up to a 21.6% increase compared to the control. Notably, the ‘Çeliksu’ cultivar responded strongly to SNP, while ‘Rizpem’ showed weak germination, regardless of treatment. Seedling growth, as measured by plant height and node number, was also influenced by both treatment and cultivar, with 5 BB again showing the most robust development. Multivariate analyses revealed strong correlations across germination dates and growth traits. Higher SNP concentrations (1500–3000 ppm) consistently promoted better germination and seedling vigor than GA₃ and untreated controls. These results highlight the importance of considering cultivar-specific responses and suggest that well-calibrated SNP applications could be a valuable tool for improving seed-based propagation in grape breeding programs.