Organic Reserves, Axillary Bud Activity, and Herbage Yields of Smooth Bromegrass as Influenced by Time of Cutting, Nitrogen Fertilization, and Shading1

Abstract

Smooth bromegrass (Bromus inermis Leyss.) was sampled at eight stages of spring growth for percentages of total available carbohydrates (TAC) and total N in the storage organs, weight of storage organs, number of tillers per plant, and number and activity of tillers developed in vitro by basal axillary buds. Results were compared with regrowth produced 7 weeks after each spring harvest under treatments of N fertilizer, shading, and association with alfalfa.Percentage TAC, weight of storage organs, and activity of the basal axillary buds generally increased as bromegrass advanced from young tillering to late maturity stages of growth. Percentage total N in storage organs was highest in young tillering plants, declined until the plants headed, and then increased. Tiller numbers per plant decreased from young tillering to headed growth stages and then remained constant. Number of active axillary buds on bromegrass declined until plants headed and then increased.Percentage TAC, weight of storage organs, and number of tillers per plant at the time of the spring harvests had little association with the amount of regrowth produced after 7 weeks. Number of axillary buds and their activity were more closely associated with regrowth, and total N concentration in the storage organs and regrowth were positively correlated under all treatments.