Cone enhancement in Abies amabilis using GA(4/7), fertilizer, girdling andtenting

The demand for Abies amabilis (Dougl. Ex Loud) Dougl. Ex Forbes, Pacific si lver fir seed has increased in British Columbia in recent years but the sup ply of wild seed is limited due to periodic cone crops and difficulty and h igh cost of cone harvest. Several clonal seed orchards have been establishe d but cone production is very low. A study was undertaken to enhance cone p roduction in a clonal seed orchard grafted in 1984. Five treatments were ap plied with 20 trees per treatment. Treatments began on 20 May 1998. Each tr ee was given two applications of GA(4/7) at I week interval, 20 and 27 May (early application) or 27 May and 3 June (late application). Ramets in trea tment 2 received early GA(4.7) application + fertilizer + girdling. Ramets in treatment 3 received a similar treatment but given late. Ramets in treat ment 4 received early GA(4.7) application + fertilizer + girdling + tenting . Ramets in treatment 5 received a similar treatment but given late. Ramets in treatment I received one injection of 80% ethanol but no GA(4/7) on 30 May. Each treatment had 10 trees in which vegetative bud burst was early an d 10 trees in which bud burst was late. Pollen and seed cone abundance was measured in April 1999. Only 10% of control ramets produced seed cones (0.7 5 cones/ramet). In treatment 2, 45% of ramets produced seed cones (8.4 cone s/ramet). In treatment 3, 35% of ramets produced seed cones (2.3 cones/rame t). In treatment 4, 70% of ramets produced seed cones (23.1 cones/ramet). I n treatment 5. 75% of ramets produced seed cones (21.2 cones/ramet). Pollen cone enhancement was statistically significant for treatments 2-5 over con trols but production was not as dramatic as for seed cones because most con trol ramets produced some pollen cones. (C) 2001 Elsevier Science B.V. All rights reserved.