Genetic analysis and selection for wheat yield in drought-stressed and irrigated environments

Abstract

Wheat (Triticum aestivum L.) cultivars grown in the southern Great Plains of the U .S .A. are exposed to a wide range of moisture conditions due to large fluctuations in the amount and frequency of rainfall . Yield stability under those conditions is therefore a desirable trait for wheat breeders . Our primary objective was to quantify various genetic parameters for grain production in drought-stressed and irrigated environments . We also attempted to predict and measure yield responses when selection is practiced in either droughtstressed or irrigated environments, or both . Seventy F2-derived lines from the cross, TAM W-101/Sturdy, were evaluated at Goodwell, OK, under irrigated and naturally drought-stressed conditions in 1987 and 1988 . Genetic variance and heritability estimates were higher in the irrigated environment than in the drought-stressed environment . The genetic correlation coefficient for yields in the two environments was 0.20 ± 0 .16, indicating that selection of widely adapted genotypes requires testing in both environments . Based on the genetic variance/covariance structure of this particular population, the linear index which maximized the combined expected gain in both environments was 0 .66Y, + 0 .34Y2, in which Y, and Y2 are yields in the irrigated and drought-stressed environments . This index is not expected to apply across all populations ; rather, it further supports the hypothesis that testing in either environment alone (drought stressed or irrigated) may not be most effective for increasing either mean productivity or yield under drought stress.

The Inheritance of Yield and Yield Components of Five Wheat Hybrid Populations Under Drought Conditions

“…Moisture stress is ultimately reflected in the depressed yields. Magnitude of yield depression is perhaps the most practiced measure of drought resistance of wheat plant (Uddin et al 1992;Cooper et al 1994;Reynolds et al 2001;Foulkes et al 2004). Harvest index in wheat declines as water application decreases.…”

Genetic parameters of wheat populations in environments with contrasting temperatures

“…It was expected due the way how it is calculated. Some studies verified, when comparing favorable conditions with unfavorable conditions, that genetic variance decreases, while the error variance can increase (Ud-Din et al 2004, Brancourt-Hulmel et al 2005. In situations like that would be harder to detect significant differences between the genotypes (Banziger et al 1999).…”

The effects of drought on rice cultivation in sub-Saharan Africa and its mitigation: A review

“…Therefore, it has become necessary to identify more efficient breeding options based on the use of indirect selection methodology (Falconer, 1989). Even though there is extensive evidence that selection under target stresses may accelerate breeding gains for stress environments (Atlin and Frey, 1990;Ceccarelli et al, 1992;Ud-Din et al, 1992;Bänziger et al, 1997), the difficulty of choosing appropriate selection environments, given a highly variable target environment, may limit the identification of superior genotypes. While breeding programs in high-income countries may resort to realtime GIS information for adequately weighting information from METs (Podlich et al, 1999), these opportunities rarely exist in low-income countries as there is a lack of both real-time GIS information and resources for conducting a large number of METs.…”