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This article in CS

  1. Vol. 36 No. 5, p. 1401-1405
    Received: Aug 31, 1995

    * Corresponding author(s): clarke@em.agr.ca
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Considerations in Design and Analysis of Experiments to Measure Stomatal Conductance of Wheat

  1. J. M. Clarke  and
  2. F. R. Clarke
  1. S emiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, Swift Current, SK Canada S9H 3X2
    D ep. of Crop Science and Plant Ecology, Univ. of Saskatchewan, Saskatoon, SK S7N 5B5



Stomatal conductance of wheat (Triticum spp.) is frequently measured in studies of adaptation. The objectives of this study were to determine the effects of diurnal environmental variation on observed differences in stomatal conductance among durum wheat (T. turgidum L. var. durum) genotypes and to assess techniques to improve precision in irrigated field trials. Stomatal conductance measurements were made with a steady-state porometer, usually on clear, calm days because conductance declined by as much as 25% as clouds briefly obscured the sun. Variation in leaf temperature and photosynthetically active photon flux density were not consistently effective covariates for adjustment of observed conductance values. Adjustment for environmental variability in stomatal conductance with a spatial analysis technique improved precision relative to randomized complete-block analysis in five of six cases and improved correlation among sampling dates. Increased replication rather than increased sub-sampling within replications would facilitate growing trials with more treatments without loss of precision or additional cost.

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