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Crop Science Abstract -

Leaf Water Content and Gas-Exchange Parameters of Two Wheat Genotypes Differing in Drought Resistance


This article in CS

  1. Vol. 30 No. 1, p. 105-111
    Received: Oct 24, 1988

    * Corresponding author(s):
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  1. Steven W. Ritchie,
  2. Henry T. Nguyen  and
  3. A. Scott Holaday
  1. D ep. of Botany and Plant Pathology, Purdue Univ., West Lafayette, IN 47909
    D ep. of Agronomy, Horticulture, and Entomology
    D ep. of Biological Sci., Texas Tech. Univ., Lubbock, TX 79409



It is still unclear what parameter(s), other than grain yield, might be a suitable indicator in a wheat (Triticum aestivum L.) breeding program for drought resistance. In this study, the leaf relative water content (RWC) and gas-exchange parameters were compared between a drought-resistant winter wheat genotype (cv. TAM W-101) and a drought-susceptible genotype (cv. Sturdy) to determine if these physiological parameters contribute to drought resistance in TAM W-101. Plants were grown under well-watered conditions in growth chambers until drought stress was imposed by limited watering of plants at anthesis or during vegetative growth. In both growth stages, TAM W-101 maintained a higher RWC and apparent photosynthesis (A) than Sturdy under moderate to severe drought stress. TAM W-101 plants also maintained a higher photosynthetic capacity (higher A at a given intercellular CO2 concentration [Ci]) under stress than did Sturdy in both growth stages. Photosynthetic water use efficiency (pWUE = A/stomatal conductance) generally increased with stress severity until very severe stress levels were attained. Thus, genotypic pWUE comparisons using stressed plants should be evaluated on a water-status basis (e.g., RWC) to avoid the confounding effect of stress severity on pWUE. TAM W-101 tended to have higher pWUE (RWC basis) than Sturdy under moderate to severe stress conditions, but not under well-watered conditions. High leaf RWC, A, and photosynthetic capacity are traits that may contribute to drought resistance in TAM W-101.

This work was supported by a grant from the Southwest Consortium on Plant Genetics and Water Resources (USDA-CSRS-86-2-2748) and by grant from the Texas Advanced Technology Research Program. Contribution of the College of Agric. Sciences, Texas Tech Univ. Journal no. T-4-221.

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Copyright © 1990. Crop Science Society of America, Inc.Copyright © 1990 by the Crop Science Society of America, Inc.