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This article in CS

  1. Vol. 21 No. 2, p. 253-255
    Received: Nov 19, 1979

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Seminal Root Morphology and Water Use of Wheat II. Genetic Variation1

  1. R. A. Richards and
  2. J. B. Passioura2



The resistance to the longitudinal flow of water through the seminal roots of a wheat (Triticum spp.) plant depends largely on the number of seminal axes and on the diameters of their main xylem vessels. With a view to increasing this resistance by breeding, the nature and extent of genetic variation in these root characters were investigated in over 1,000 accessions of both modern and primitive wheats with different ploidy levels and in populations derived from them. The diameter of the xylem vessel proved to be the more tractable character. This was because (1) no accession, or line derived from different F2 populations, had substantially fewer seminal axes than average, whereas some land-race wheats with acceptably narrow vessels were found, and (2) parent-offspring regressions established that the heritability of vessel diameter was considerably higher than that of the number of axes. Vessel diameter can be manipulated genetically as was shown by the significant responses to selection in different populations.

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