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United States Department of Agriculture

Agricultural Research Service

Title: Elemental Uptake in Relation to Root Characteristics of Tall Fescue

Authors
item Shewmaker, G - UNIVERSITY OF IDAHO
item Johnson, Douglas
item Mayland, Henry
item Martin, S - UNIV. OF GEORGIA
item Hansen, Susie

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2003
Publication Date: June 1, 2004
Citation: Shewmaker, G.E., D.A. Johnson, H.F. Mayland, S.A. Martin, and S.B. Hansen. 2004. Elemental uptake in relation to root characteristics of tall fescue. Communications in Soil Science and Plant Analysis 35: 1339-1355.

Interpretive Summary: HiMag, a selection of tall fescue was selected for high magnesium concentration in leaves to reduce grass tetany risk to livestock. However, the mechanism for enhanced magnesium uptake in HiMag leaves has not been determined. The objective of this study was to investigate if increased magnesium uptake in HiMag could be explained by differences in elemental distribution among plant parts, root characteristics, or organic acid concentrations compared to its parental cultivars ('Kentucky 31' and 'Missouri 96'). Tall fescue was grown in the field in Idaho, and vegetation and soil cores of 7.6-cm diameter were sampled to a 45-cm soil depth in 15-cm increments. Various characteristics were determined for leaves, crowns, and roots of the test plants. Risk of causing grass tetany was lower in HiMag than its parents in both 1994 and 1995. However, HiMag generally did not differ in the various plant characteristics, suggesting that HiMag probably has an active uptake or transport mechanism for magnesium.

Technical Abstract: HiMag, an accession of tall fescue (Festuca arundinacea Schreb.), was selected for high Mg concentration in leaves to reduce grass tetany risk to ruminants. However, the mechanism for enhanced Mg uptake in HiMag leaves has not been determined. The objective of this study was to investigate if increased Mg uptake in HiMag could be explained by differences in elemental distribution among plant parts, root characteristics, or organic acid concentrations compared to its parental cultivars, 'Kentucky 31' (KY31) and 'Missouri 96' (MO96). Tall fescue was grown in the field in Idaho, and vegetation and soil cores of 7.6-cm diameter were sampled to a 45-cm soil depth in 15-cm increments. Mass and ash were determined for leaves, crowns, and roots. Leaf area, root length, root area, root length density, elemental concentration and uptake (K, Ca, Mg, Na, and P), and malate and citrate concentrations also were determined. Leaf Mg concentration was higher in HiMag than its parental cultivars. HiMag generally did not differ in crown and root elemental concentrations from its parents. Risk of causing grass tetany was lower in HiMag than KY31 and MO96 in both 1994 and 1995. Root length, area, and mass were not related to cation concentrations in the three tall fescue accessions, suggesting that HiMag may have an active uptake or transport mechanism for Mg.

Last Modified: 12/22/2014
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