Heritability of Waterlogging Tolerance in Wheat
2005
Collaku, A. | Harrison, S. A.
Tolerance of wheat (Triticum aestivum L.) to waterlogging is related to many morphological and physiological traits that are under a strong environmental influence. Often their genetic control is confounded by environmental stress. The objective of this study was to estimate narrow-sense heritability for grain yield and yield components under waterlogging conditions and to provide selection criteria for waterlogging tolerance in early generations. We studied 80 families derived from four segregating soft red winter wheat populations in the F₂ generation. The experiment was conducted under the effect of 5 wk of waterlogging stress. The Restricted Maximum Likelihood (REML) method was used to estimate genetic variance components. In contrast to traditional methods, REML has no limitations on the mating design and accounts for the relationships among families in a breeding population. Grain yield had the lowest heritability (h ² = 0.25). The highest heritability estimates were found for kernel weight (0.47), chlorophyll content (0.37), and tiller number (0.31). Strong genetic correlations were observed between grain yield and kernel weight (r = 0.56), and between grain yield and tiller number (r = 1). Selection for a relatively highly heritable trait, such as kernel weight, would be an effective way to improve waterlogging tolerance in early generations, as grain yield has a low heritability. Genetic and phenotypic information about traits was used to construct selection indices. A yield improvement of 17% is expected by selection on the basis of the index: grain yield-kernel weight-tiller number.
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