VEGETATIVE PROPAGATION OF CONIFERS: VI. HORMONE SOLUTION AND DUST TREATMENTS OF SPRUCE CUTTINGS PROPAGATED IN GREENHOUSE AND OUTSIDE FRAMES

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Four monthly collections of dormant Norway spruce cuttings, January to April, were treated with indolylbutyric acid solutions and propagated in sand in a greenhouse. February and April collections gave better rooting than those of the other two months, while there was appreciably greater mortality of the March and April collections. The results with short cuttings were uniformly superior to those obtained with long cuttings. Other cuttings of the April collection were propagated outside. The short cuttings responded more favourably to outside conditions, while the long cuttings gave equally poor results inside and outside. Indolylbutyric acid treatment had no beneficial effect and was followed by reduced rooting and increased mortality at concentrations from 20 to 60 p.p.m.Results of a late March collection of Norway, white, and black spruce cuttings treated with talc dusts containing indolylacetic acid, cane sugar, and organic mercury, indicated that Norway spruce rooted more readily than the two other species. Treatment failed to have a beneficial effect, although injury from indolylacetic acid was somewhat reduced by its combination with organic mercury.The results of these and the other experiments reported indicate that short Norway spruce cuttings over the period from January to April root to the extent of about 50%. A May collection, an early June collection with new growth on the cuttings, and a late June collection in which the cuttings were made from new growth only, gave inappreciable rooting. Similar new-growth cuttings did, however, give some rooting when propagated in sand watered with nutrient salts.