Seed germination and seedling growth of rice bean and grain amaranth as influenced by allelopathic effect of walnut [Juglans regia L.] leaf extracts under west Himalayan agri-silvi system.

A laboratory experiment was conducted to observe the effect of Jug/ans regia L. leaf extracts on germination and subsequent seedling growth of ricebean (cv. PRR 1) and grain amaranth (cv. PRA 3) under West Himalayan agri-silvi system. Seven treatments comprised of distilled water (Control = 0), 2, 4, 6, 8, JO and I 2 g of leaf extracts per litre of distilled water were employed. The effect of aqueous extracts was found inhibitive indicating a direct proportional relationship with concentration dependent manner on seed germination and subsequent seedling growth of grain amaranth. In variably there was a decrease in root, shoot as well as seedling length, fresh and dry weight of seedling and vigour index I and II with increasing walnut leaf extracts concentration on grain amaranth. However, ricebean seed showed a considerable tolerance against walnut leaf extract and no significant reduction was observed for germination up to 80% leaf extract concentration, while subsequent seedling growth i.e. root, shoot and seedling length, seedling fresh and dry weight along with vigour index I and II were inhibited on concentration dependent manner of walnut leaf extracts. Walnut [Juglans regia L.], is a large deciduous tree distributed in the Indian Central Himalaya between 1375-3350 msl, extending in the west to Afghanistan and east to Bhutan. It occurs both as wild form as well as under cultivation along the risers of the field in western Himalayan traditional agri-silvicultural system. Presence of trees in the agro­ forestry system results in the exposure of associated crops due to release of allelo-chemicals of the fallen leaves which after decomposition leaches into the soil