Silicon has been widely recognized for its beneficial role in enhancing plant tolerance to both biotic and abiotic stresses, although it is not classified as an essential nutrient. This study aimed to evaluate the effects of nano-silicon dioxide (SiO₂) on the germination and early seedling development of four lentil genotypes under normal and saline conditions. Seeds were exposed to three treatments: control, 100 mM NaCl, and 100 mM NaCl supplemented with 1 mM nano silicon dioxide. Germination percentage, shoot length, root length, seedling fresh weight, and dry weight were recorded over a 10-day period. A treatment-by-trait biplot model was used to visualize interactions and identify superior genotype-treatment combinations. Results showed that salinity stress significantly reduced germination and growth, while the application of nano silicon dioxide only partially mitigated these effects. The genotype G3 demonstrated the best overall performance in terms of germination percentage, shoot and root length, and seedling fresh weight under combined stress and nano-silicon treatment. Positive correlations were observed between shoot and root lengths, and between germination percentage and seedling fresh weight. These findings suggest that while nano-silicon dioxide may support early-stage growth under stress, its effectiveness is genotype-dependent and may be limited during germination.
