| Abstrakt: |
Effective screening techniques for drought resistance would be beneficial in a winter wheat (Triticum aestivumL.) breeding program. Several greenhouse and field screening techniques were evaluated for abilily to differentiate drought resistance in five cultivars reputed to differ in drought resistance and yield: Scout 66, Sturdy, TAM W‐101, TAM 105, and TAM 108. Grain yield for droughtstressed and irrigated conditions was determined in field trials on Pullman clay loam soil (fine, mixed, thermic Torrertic Paleustoll). Yield ranking, both irrigated and drought stressed, was: TAM 108 ≧ TAM 105 > TAM W‐101 = Scout 66 ≧ Sturdy. Drought susceptibility index (S) values were: 0.55, 0.57, 0.59, 0.63, and 0.63, for Scout 66, TAM 105, TAM W‐101, Sturdy, and TAM 108, respectively. These values indicate that Scout 66 has the greatest yield stability in drought, while Sturdy and TAM 108 have the least. Screening techniques that were unsuitable because they did not differentiate cultivars were germination in mannitol, rooting depth, leaf conductance, and canopy temperature. Seedling root length appeared unsuitable because of limited cultivar differentiation and high labor requirement. Seedling survival after desiccation was the most suitable technique for screening large populations. Water loss of excised leaves and leaf water potential (Ψ) are labor intensive but would be informative screening techniques for parental material and advanced lines. Water loss of excised leaves was correlated with S (least loss = lowest S). High yield was associated with low Ψ, which may be associated with high ability to retain green leaves in drought |
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