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This article in CS

  1. Vol. 17 No. 1, p. 91-93
    Received: Dec 22, 1975

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Stomatal Diffusion Resistance in Three Ploidy Levels of Smooth Bromegrass1

  1. H. Z. Lea,
  2. G. M. Dunn and
  3. D. W. Koch2



Diurnal variations in stomatal resistance and the relationship of stomatal resistance to stomatal characters were investigated in tetraploid (4×), hexaploid (6×), and normal octoploid (8×) strains of Bromns inermis Leyss. Stomatal resistance of ‘Blair’ (8.6 sec/cm) was significantly higher than for the other six octoploid cultivars (5.8 to 6.5). The range of mean stomatal resistance between 0900 and 1600 hours (Eastern Standard Time) was approximately 4.0 to 9.0 sec/cm for 8×. Within a cultivar the diurnal pattern of stomatal resistance varied, dependent on the day of measurement; however, stomata of 4× and 6× plants consistently closed earlier in the evening than did 8× plants. Octoploid plants had the lowest mean stomatal resistance (5.1 sec/em), 6× intermediate (6.9), and 4× the highest (8.6), based on measurements between 0700 and 1930 hours for four measurement dates in June 1974.

A highly significant negative correlation (r = −0.58) was obtained between stomatal resistance, measured with a diffusion porometer, and total stomatal aperture estimated as the product of stomatal width ✕ length ✕ frequency. Stomatal width was the most important single factor in estimating total stomatal aperture (r = −0.92) and stomatal resistance (r = −0.54). Stomatal resistance was not affected significantly by leaf position on the culm.

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