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This article in CS

  1. Vol. 30 No. 1, p. 207-212
     
    Received: Sept 26, 1988
    Published: Jan, 1990


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doi:10.2135/cropsci1990.0011183X003000010045x

Digestibility and Cell-Wall Components of Alfalfa Following Selection for Divergent Herbage Lignin Concentration

  1. Kevin D. Kephart ,
  2. D. R. Buxton and
  3. R. R. Hill
  1. P lant Science Dep. South Dakota State Univ., Brookings, SD 57007
    U SDA-ARS, 1565 Agronomy Hall, Iowa State Univ., Ames, IA 50011
    U SDA-ARS, U.S. Regional Pasture Res., Lab., University Park, PA 16802

Abstract

Abstract

Breeding schemes to improve alfalfa (Medicago sativa L.) forage quality based on total herbage chemical composition can result in altered morphology. Additionally, cell-wall composition of plant parts also may be altered. This study investigated the effects of divergent selection for lignin concentration in total herbage of alfalfa on concentration of cell-wall components and digestibility of stems. Two groups of alfalfa previously derived from herbage-based selection were studied. Group 1 consisted of six two-parent Syn-2 lines randomly selected from ‘Saranac-AR’ for high (HL) or low (LL) acid-detergent lignin (ADL) concentration in the total herbage. Group 2 had 11 HL and 13 LL lines produced from crossing pairs of parents of the Group 1 lines. Neutral-detergent fiber (NDF) concentration in stem bases was 4 and 3% greater in HL lines than in LL lines in Group 1 and 2, respectively. Likewise, herbage NDF concentration was 8% greater in HL than in LL lines of Group 1 and 4% greater in Group 2. There were no differences between divergent lines in NDF concentration of stem tops. Lignin concentration in cell walls of Group 1 was 8 and 6% greater in LL lines than in HL lines in stem tops and stem bases, respectively. In Group 2, the LL lines had 2% greater cell-wall lignin concentration than HL lines in both stem fractions. Total-herbage NDF concentration correlated more closely with leaf-to-stem ratio of entire plants (r = − 0.96 and −0.78 for Group 1 and 2, respectively) than with stem length and maturity. Thus, herbage-based selection for improved nutritive quality of alfalfa results in complex changes in stem cellwall component concentrations in addition to large morphological changes.

Contribution of the USDA-ARS Iowa Cluster program of the U.S. Dairy Forage Res. Ctr. and Iowa State Univ. Journal Paper no. 13237 of the Iowa Agric, and Economic Exp. Stn., Project no. 2709.

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Copyright © 1990. Crop Science Society of America, Inc.Copyright © 1990 by the Crop Science Society of America, Inc.