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This article in AJ

  1. Vol. 70 No. 5, p. 775-779
    Received: Sept 6, 1977

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Use of a Bleach Test to Screen Single-head Sorghum Selections for the Presence of a Testa Layer1

  1. K. D. Kofoid,
  2. J. W. Maranville and
  3. W. M. Ross2



The development of random mating populations of sorghum [Sorghum bicolor (L.) Moench] has resulted in an increase in the frequency of material with a testa layer. Since the testa layer has been associated with tannin, genotypes with a testa need to be identified in these populations with ease and certainity. Hence, a procedure using KOH and bleach (6% NaOCI by weight) to determine the presence of a testa layer in sorghum was modified for use on single-head selections and was evaluated for its usefulness as a screening technique.

Three concentrations of KOH:bleach (1:6, 1:5, and 1:4 w/v) at each of three water bath temperatures (50, 60, and 70 C) for three time periods (10, 15, and 20 min) were. tested to determine the optimum conditions for maximum color development of the kernels. Significant main effects were found for genotypes, time, and temperature. Partitioning of the genotype sum of squares into single degree of freedom comparisons showed significant differences between genotypes with and without a testa. Pericarp pigmentation also was found to significantly affect the rating in both the testa and nontesta material. However, this effect was not judged to be detrimental to the determination of presence or absence of a testa layer. Significant differences were found between waxy and yellow endosperm material, but this was probably due to pericarp pigmentation. Significant 2, 3, and 4-way interactions indicated that no single combination of treatments was optimum for all entries. However, immersing kernels in a concentration of 1:5 (w/v) KOH:bleach at a water bath temperature of 60 C for 15 min resulted in a maximum rating for genotypes with a testa. Use of this procedure allows for the screening of a large number of selections for the presence of a testa layer with relative ease and reliability.

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