Germination Response of Eggplant (Solanum melongena L.) to Varying Potassium Nitrate Concentrations and Priming Durations

Eggplant (Solanum melongena L.) is an economically important solanaceous crop with orthodox seeds. Seed germination potential decreases due to prolonged storage resulting in delayed germination, which can consequently cause production lossess; thus, seed priming is practiced. In this study, the effect of various KNO3 concentrations (0.0625, 0.25, 1, and 4%) and priming durations (6, 12, 24, and 48 h) on eggplant seed germination was assessed using a between-paper germination test. The experiment followed a completely randomized design with four replicates per treatment, each consisting of 50 seeds. The results showed that germination was affected by the KNO3 concentration and the priming duration. The final germination percentage (FGP) revealed that priming significantly improved eggplant seed germination, but the differences for many priming treatments were non-significant (p ≥ 0.05) except in 0.0625% KNO3 applied for 24 and 48 h, which resulted in lower FGP than the non-primed seeds (87%). The germination index (GI) and germination rate index (GRI) index revealed that priming with 0.25–4% KNO3 for 6, 12, and 24 h can lead to significantly improved germination pattern (GI = 59.5–124.75 vs. control GI = 50; GRI = 9.17–11.82 vs. control GI = 8.88). The mean germination time (MGT) also revealed that KNO3 priming hastened seed germination, especially with 24-h priming duration (MGT = 8.50–9.60 d vs. control MGT = 10.08 d), whereas 6-h priming had no significant difference. Among the treatments, priming with 4% KNO₃ for 24 h resulted in the highest germination performance across all measured parameters. Moreover, priming with water and 0.0625% KNO3 was most effective when applied for 6 h, whereas prolonged exposure (≥ 24 h) can lead to slow and delayed germination. These results can be the basis for more efficient and effective seed priming using KNO3 in eggplant.