Pre-sowing Seed Treatment Protocol for Standardisation of Nursery Technology of Malabar Neem (Melia dubia Cav.) in the Lower Foothills of Himachal Pradesh

Abstract

Malabar Neem (Melia dubia Cav.) is a fast-growing, multipurpose indigenous tree species used in agroforestry and plantation forestry because of its rapid growth, short rotation, wood quality and economic value. Demand for quality seedlings is increasing in India; however, poor and inconsistent germination, associated with dormancy caused by the hard drupe wall and lignified endocarp, constrains large-scale nursery production. This study standardised a pre-sowing seed-treatment protocol for improving drupe germination, seedling growth and planting-stock quality of Melia dubia under polyhouse conditions in the lower foothills of Himachal Pradesh. The experiment was conducted at the Experimental Forestry Research Farm, COHF, Neri, Hamirpur, Himachal Pradesh, India, during 2024-25. Ten treatments were evaluated in a Completely Randomised Design with four replications: untreated control, hot-water treatment, cold-water soaking, cow-dung slurry soaking, sandpaper scarification, concentrated H₂SO₄ treatment, GA₃, BAP, H₂O₂ and PEG treatment. A total of 400 drupes per treatment were sown to assess germination, seedling growth, biomass production and seedling quality indices. Treatment effects were significant (p < 0.05) for germination and growth parameters. Concentrated H₂SO₄ for 15 minutes recorded the highest germination (56.50%), followed by sandpaper scarification (50.00%) and cow-dung slurry soaking (44.75%), whereas the control recorded the lowest germination (25.00%). The same treatment produced the greatest seedling height (125.25 cm), collar diameter (80.08 mm), root length (12.45 cm), Seedling Vigour Index (7075.25) and Seedling Quality Index (11.77), and the lowest Seedling Sturdiness Quotient (1.57). Chemical scarification with concentrated H₂SO₄ for 15 minutes is therefore an effective treatment under the study conditions.