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This article in CS

  1. Vol. 10 No. 6, p. 710-712
     
    Received: June 13, 1970


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doi:10.2135/cropsci1970.0011183X001000060035x

Two Cycles of Directional Selection for Improved Nutritive Value of Alfalfa1

  1. John S. Shenk and
  2. Fred C. Elliott2

Abstract

Abstract

A 6-hour in vitro dry matter disappearance (GH-DMD) procedure was used to evaluate individual progeny of ‘Vernal’ (Medicago sativa L. and Medicago falcata L.) and ‘DuPuits’ (Medicago sativa L.) clones selected for high or low 6H-DMD values. Progeny derived from clones with high GH-DMD values had consistently higher 6H-DMD values than progeny from low clones. Additional clones of ‘Culver’ MSA-C4, MSB-C4, Medicago glutinosa M.B., and Vernal were screened for high or low 6H-DMD values over two harvests. Selected clones from Vernal and DuPuits progeny and from the five unselected populations were recombined for a second cycle of directional selection.

Correlations between yield and 6H-DMD were negative or near zero. Cell wall analysis of clones selected for a second cycle of improvement indicated a significant positive relationship between total cell wall constituents (NDF) and 6H-DMD values of the forage.

Second cycle clones had significant general and specific combining abilities for yield as well as leaf and NDF content. Progeny from clones with high GH-DMD values were higher in leaf content but lower in NDF content than progeny from clones with low GH-DMD values. Comparisons of selected two-clone combinations in the first and second cycles indicated second cycle selection was effective in separating progeny means.

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