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Enhancement of ABA responsiveness in wheat embryos by high temperature*



    Corresponding author
    1. United States Department of Agriculture, Agriculture Research Service, Wheat Genetics, Quality, Physiology & Disease Research, Washington State University, Pullman, WA 99164-6420, U.S.A.*
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  • *

    Contribution from the USDA-ARS in cooperation with the College of Agriculture and Home Economies Center. Washington Stale University, Pullman, WA, U.S.A. Scientific paper no. 7832.

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Dr M. Walker-Simmons, USDA/ARS, Johnson Hall 209, Washington State University, Pullman, WA 99164-6420. U.S.A.


Abstract. Mature wheat (Triticum aestivum L.) grain often possesses high-temperature dormancy which restricts the grain from germinating at warm temperatures (25–30°C). Isolated embryos from such grain exhibited little high-temperature dormancy when germinated in water. Dormancy was restored by the application of abscisic acid (ABA) to the embryos. The ability of ABA to block germination in isolated embryos was enhanced significantly by elevating the germination temperature. ABA was 100 times more effective in reducing embryonic germination at 30°C than at 15°C. These temperature effects on embryonic response to ABA are a useful system for studying the mechanism of ABA action in seed dormancy.