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Wheat Information Service
Number 91: 11-14 (2000)
Research article

Genetic variability and inheritance of grain dormancy in three white-grain wheats

R.E.Allan

USDA-ARS, Washington State University, PO Box 646420, Pullman, WA 99164, USA


Summary

Breeding for high grain dormancy is the main approach for preventing preharvest sprouting in white-grain wheat (Triticum aestivum L). Several white-grain sources express dormancy including Brevor (BV), Clark's Cream (CC) and Losprout (LS). This study examined the genetic expression and relatedness of dormancy among these sources. The F2:4 and F2:5 progenies of five populations were scored for dormancy in 1989 and 1993, respectively. The populations included crosses between BV, CC, and LS with Greer (GR), a nondormant variety, plus crosses of LS with BV and with CC. Germinability at 30C was determined to assess dormancy using a definitive germination percent (G%). Parent-offspring heritabilities included low to moderately high estimates varying from 0.17 to 0.63. The G% means of F2:5 progeny of all crosses were not normally distributed. LS had higher dormancy than CC and BV while CC was more dormant than BY LS has some dormancy genes in common with BV and CC and may have others which they lack. Using LS as the primary source of dormancy is justified. Testing large populations of several hundred F2-derived individuals should facilitate recovering lines with dormancy similar to LS.

Key words: preharvest sprouting, Triticum aestivum L.


Introduction

Preharvest sprouting (PHS) of wheat (Triticum aestivum L.) is a serious problem in many major wheat production areas especially where white-grain varieties, are grown. Several morphological and physiological traits influence the expression of PHS but grain dormancy is considered to be the most important process (Hong 1979; Li and Foley 1997). Wheats with white grain are considered to be more predisposed to PHS than red-grain varieties; yet a number of white grain wheat genotypes have appreciable grain dormancy and resistance to PHS (McCrate et al. 1982; Walker-Simmons 1987; Paterson and Sorrells 1990; DePauw et al. 1993; Mares 1993). The inheritance of dormancy among white-grain wheats has received considerable attention (Upadhyay and Paulsen 1988; Paterson and Sorrells 1990; Allan 1993; Anderson et al. 1993). Heritability estimates of dormancy have ranged from low (Paterson and Sorrells 1990) to medium (Upadhyay and Paulsen 1988; Allan 1993). Resistance has been reported to he normally distributed and quantitatively inherited (Paterson and Sorrells 1990; Allan 1993; Sorrells and Anderson 1996). Anderson et al. (1993) identified eight genomic regions controlling resistance to PHS in two populations. In contrast Mares (1996) reported that two independent recessive genes located on chromosome 3D controlled the high dormancy phenotype of AUS1408. The objective of this study was to examine the genetic expression of dormancy in three white-grain wheat sources and to determine whether they had similar or different genetic mechanisms controlling dormancy.

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