Optimizing Seed Germination in Fresh and Aged Guava (Psidium guajava L.) Seeds Using Different Chemicals Scarification Treatments

The present investigation was conducted during 2024–2025 at the Horticulture Laboratory of Shree Guru Gobind Singh Tricentenary University, Gurugram (Haryana). The study evaluated the influence of various pre-sowing treatments, including water soaking, hot water soaking (70° C and 80° C), sulphuric acid (10% and 20%), gibberellic acid (GA) @200 ppm and 400 ppm, and thiourea (@1000 ppm and 2000 ppm), on seed germination and seedling growth parameters in both fresh and one-year-old guava seed lots. The data were recorded on standard germination percentage, days to emergence of seedling, mean germination time, survival percentage, seedling length, seedling dry weight, vigour indices- I and II and speed of germination. The results revealed that GA at 400 ppm for 24 hours consistently outperformed other treatments, recording the highest germination percentage (57.61% in fresh seeds and 50.56% in one-year-old seeds), minimum days to emergence (17 and 20.33 days, respectively), maximum survival percentage (59.67% and 54.00%), longest seedling length (5.60 cm and 4.20 cm), and greatest seedling dry weight (328.00 mg and 281.00 mg). This treatment also enhanced vigour indices- I and II and speed of germination. GA at 200 ppm and thiourea at 1000 ppm also showed promising results, though inferior to GA3 at 400 ppm. The findings demonstrate that pre-sowing seed treatment with GA (400 ppm) is highly effective in improving germination and seedling growth of guava seeds, thereby offering a practical strategy for enhancing seedling establishment in nurseries.