Cotton (Gossypium hirsutum L.) is a globally significant crop grown primarily for its fibre. The present investigation was undertaken to study the allelopathic effect of Azadirachtaindica (Neem) leaf extract on extract on in-vivo seed germination and early seedling growth in cotton. Different concentrations of neem leaf extract viz., 5%, 10%, 15%, 20% and 25% were applied to cotton seeds and seedlings grown in soil, and their effects were compared with control.The results revealed that neem leaf extract significantly influenced seed germination and seedling vigour. The highest seed germination percentage (79.2%)was recorded at 10%, 20% and 25% neem extract, followed by 70.8% germination at 5%, as compared to 54.2% in control. Seedling growth parameters also showed variation with concentration. The maximum seedling height (12.9 cm) and improved root growth were observed at 5% neem extract, indicating a stimulatory effect at lower concentrations. However, higher concentration (25%) showed reduced seedling height (10.5 cm), suggesting
an inhibitory effect at elevated doses. The study clearly indicates that low concentrations of neem leaf extract (5–15%) enhance seed germination and seedling growth, while higher concentrations adversely affect growth.
Thus, neem leaf extract exhibits concentration-dependent allelopathic effects on cotton seedlings. The findings suggest that neem leaf extract at lower concentrations can be effectively used as an eco-friendly growth-promoting agent in cotton cultivation.