Peer review

Near-isogenic lines that contrast in the presence or absence of glaucousness were developed in durum wheat (Triticum turgidum L. durum group) and common wheat (T. aestivum L.) and grown in plots in three field environments varying in soil water availability. The glaucous selections yielded significantly more grain and dry matter than non-glaucous selections in the two higher yielding environments but not in the very dry environment where average yield was 66 gm-2. No differences within or between lines were found in soil water extraction patterns. Furthermore, leaf water potentials determined at predawn and midday exhibited no consistent differences between glaucous and non-glaucous selections. Lines selected for glaucousness varied in wax content of the different plant parts. Although differing in glaucousness, the glaucous selections did not necessarily exhibit greater amounts of epicuticular wax. Field gas exchange measurements for flag leaves and sheaths also indicated no beneficial or detrimental effects of glaucousness at saturating light and optimum temperature for photosynthesis. Surface reflectances in the 400 to 700 nm wavelengths were the same for the adaxial surface of the flag leaf, but were 8 to 15% higher in the glaucous than nonglaucous selections of one line for the ear, sheath, and abaxial flag leaf surface. Reflectances increased linearly with amount of epicuticular wax and were greater in the driest environment. The greater yield of the glaucous over the non-glaucous lines is discussed in relation to differences in reflectance and the possible influence of glaucousness on tissue temperature, leaf area duration, and other factors.

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