Light Quality and Stem Numbers in Cool-Season Forage Grasses
The number of stems produced by cool-season forage grasses is a major factor in determining forage production. Knowledge of factors that influence stem numbers will be useful in developing proper management practices. Objectives of this study were to (i) determine total stem numbers and the amount of far-red (FR) and red (R) light at the crown level in canopies of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schultes], western wheatgrass [Pascopyrum smithii (Rydb.) Gould], and smooth bromegrass (Bromus inermis Leyss.) that were hayed, grazed, or ungrazed; and (ii) evaluate the relationship between the FR/R ratio at plant crown level and stem numbers. The study was conducted during 1989,1990, and 1991 at Mandan, ND, USA. Management practices produced differences in both FR/R ratios and stem numbers. Treatment effects on stem numbers were consistent over years for smooth bromegrass whereas treatment × year interactions were significant for crested wheatgrass and western wheatgrass. Generally, stem numbers were greatest for all species that were hayed followed in order by grazed and ungrazed treatments. Grazed and ungrazed plants developed longer leaves and stem internodes than did hayed plants. The relationship between FR/R ratio and stem numbers for all treatments was consistent with previous reports that stem numbers of grasses may be influenced by the FR/R ratio at the crown. The decline in stem numbers of ungrazed stands suggests that to maintain vigorous stands of these species requires an appropriate level of management.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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