Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2002
Publication Date: 9/1/2003
Citation: KARN, J.F., FRANK, A.B., BERDAHL, J.D., POLAND, W.W. WATER, NITROGEN AND PLOIDY EFFECTS ON RUSSIAN WILDRYE MINERAL CONCENTRATIONS. JOURNAL OF RANGE MANAGEMENT 56:534-541. 2003. Interpretive Summary: Russian wildrye, both the traditional (diploid) and new (tetraploid) cultivars could provide valuable spring and fall grazing, in the Northern Great Plains, but sometimes early-season use results in grass tetany, a deadly metabolic disease of milking cows. It is essential to obtain more information on the factors that affect concentrations of magnesium (Mg), calcium (Ca), and potassium (K) which are related to the incidence of gras tetany, as well as other minerals necessary for optimum grazing cattle production. A study was undertaken to determine the affect of growing- season water (50 and 150% of average), and nitrogen (N) fertilizer (10 and 134 kg N/ha), on mineral concentrations of diploid and tetraploid Russian wildrye plants harvested at 4 stages of maturity over 3 years. Traditional diploid plants usually had slightly higher mineral levels, but stem P was higher in the new tetraploid plants. The 150% growing-season water level increased grass phosphorus (P) levels, but had minimal effects on other mineral concentrations. Fertilizer N increased forage levels of Ca, K, copper (Cu), and zinc (Zn) and decreased levels of P. Advancing plant maturity had a negative effect on P and Zn concentrations, but Ca and Mg in leaf tissue increased as plants matured. Levels of P, Ca, Mg and Cu were marginal for high producing beef cattle at some stages of maturity. However, we found little difference between the traditional diploid and new tetraploid grasses, and no mineral concentration effects due to N or growing-season water that would adversely affect the safety and nutritive quality of Russian wildrye forage.
Technical Abstract: High quality forage for spring and fall grazing can be obtained from Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], a cool-season bunchgrass. However, little is known about mineral concentrations critical to livestock production, especially in the relatively new tetraploid plants. A study was undertaken to determine the extent that critical mineral concentrations in leaf and stem tissue of Russian wildrye were affected by ploidy level, growing-season water (50 and 150% of average), and nitrogen (N) fertilizer (10 and 134 kg N/ha). Plants were sampled at vegetative, boot, anthesis, and anthesis plus 10-day stages of maturity in 1994, 1995, and 1996. Ploidy level resulted in small but significant differences in some mineral concentrations, with diploid plants usually having higher levels. An exception was phosphorus (P) in stem tissue. This finding indicates that in breeding and selection for other traits, forage quality was not adversely affected. Growing-season water level als had minimal effects on mineral concentrations, except for P which was apparently enhanced (P<0.05) by higher soil water. Fertilizer N increased forage levels of calcium (Ca), potassium (K), copper (Cu), and zinc (Zn) and decreased levels of P. Advancing plant maturity had a negative effect on P and Zn concentrations, but Ca and magnesium (Mg) in leaf tissue increased as plants matured. Levels of P, Ca, Mg and Cu were marginal for high producing cattle at some stages of maturity, but we found the effects of N and growing-season water did not result in leaf or stem mineral concentration changes that would adversely affect the safety and nutritive quality of Russian wildrye.