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This article in CS

  1. Vol. 38 No. 2, p. 497-502
    Received: Oct 21, 1997

    * Corresponding author(s): lambx002@maroon.tc.umn.edu
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Root Morphology of Alfalfa Plant Introductions and Cultivars

  1. L. D. Johnson,
  2. J. J. Marquez-Ortiz,
  3. J. F. S. Lamb  and
  4. D. K. Barnes
  1. C al/West Seeds, P.O. Box 1428, Woodland, CA 95776
    I NIFAP-CELALA, APDO. Postal #247, Torreon, Coach, Mexico, 27000



Alfalfa (Medicago spp.) root morphology has a critical role in plant persistence and productivity traits. The objectives of this research were to evaluate root morphological traits for 1067 plant introductions (PIs) from diverse geographic origins and from 110 North American cultivars. All entries were grown in 2-m rows at the University of Minnesota Agricultural Experiment Station at Rosemount, MN. Plants from both studies were evaluated during autumn of the establishment year for taproot diameter (TD), lateral root number (LRN), lateral root diameter (LRD), lateral root position (LRP), and fibrous root mass (FRM). Variability was observed among PIs and North American cultivars for all traits. The range for all traits were greater in the PIs than in the cultivars. Discriminant analysis using root morphological traits to generate canonical functions separated PIs assigned to germplasm groups from different geographic origins. Among the PIs, TD and LRD were positively correlated and LRN, LRP, and FRM were negatively correlated with fall dormancy. Discriminant analysis using root traits to generate canonical functions separated the very fall dormant from the non-dormant classes. Semi-dormant classes for cultivars released before 1980 had some overlap, but some individual classes could be distinguished by root traits. Semi-dormant classes for cultivars released after 1979 could not be separated. Fall dormancy was negatively correlated with LRN, LRD, LRP, and FRM for cultivars released before 1980, but FRM was the only root trait correlated with fall dormancy for cultivars released after 1979. Our results suggest that recent plant breeding strategies for semi-dormant alfalfa has influenced the relationship between fall dormancy and root morphology. Variation observed for root morphological traits among all alfalfa entries evaluated indicated that selection for specific root modifications could be effective.

Joint contribution of the USDA-ARS and the Minnesota Agric. Exp. Stn. Paper No. 22595, Scientific Journal Series, Minnesota Agric. Exp. Stn.

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