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A Provisional Model for Smooth Brome
Management in Degraded Tallgrass Prairie

Morphological Development and Carbohydrate Reserves

Smooth brome exhibits two predominant periods of tiller emergence and development (Lamp, 1952). The most active period of tiller emergence begins after flowering in June and continues into the fall. Tillers emerging in late summer and fall do not elongate, but continue to develop leaves until inhibited by cold temperatures. Unelongated tillers remain dormant from early December until mid-March, with their terminal growing points at or below the soil surface. The second, and less active, period of tiller emergence occurs from about mid-March through early May. New tillers develop during this period, while already emerged, unelongated tillers from the previous summer and fall produce new leaves. The new tillers are, however, more numerous because summer- and fall-initiated tillers frequently do not survive the winter (Walton, 1980).

Smooth brome tiller elongation begins in early May in the central Great Plains and Midwest in response to increased day length (Lamp, 1952). Heading begins when inflorescences begin to show about the fourth week in May and this continues for about two weeks. Flowering begins about the second week in June and also lasts about two weeks. Seeds ripen in late July as the panicles turn brown.

In grasses, the amount of stored carbohydrates varies seasonally and is dependent on the growth rate, the stage of plant development, and environmental factors (White, 1973). Smooth brome carbohydrate reserves are low during two stages of development. Teel (1956) describes an annual juvenile or jointing stage of smooth brome tiller development that is characterized by rapid vegetative growth associated with tiller internode elongation and relatively low root carbohydrate storage (Fig. 2). A second carbohydrate low occurs at late panicle emergence when the floral structures develop (Eastin and others, 1964, Paulsen and Smith, 1969).

diagram showing relationship of fructose to the growth stages of smooth brome tillers
Figure 2.   Relationship between concentration of total fructose (carbohydrates) in the basal internodes of smooth brome tillers and its various growth stages: tiller emergence (TE), tiller elongation (TL), tiller heading (HE), and tiller flowering (FL).
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