Wheat kernel dormancy and + abscisic acid level following exposure to fluridone

Abstract

Summary Detached spikes from soft white winter wheat ( Triticum aestivum L.) cultivars that produce caryopses with high dormancy levels (Brevor) or low dormancy levels (Greer) were cultured from anthesis in basal media and media amended with fluridone or fluridone plus ABA. Effects of fluridone and exogenous ABA on kernel development and dormancy acquisition and maintenance were assessed by measuring fresh and dry mass of embryos and caryopses, ABA content in embryos and caryopses, and kernel post-desiccation dormancy levels. Caryopses and embryos exposed to fluridone accumulated very little ABA. Detached spike culture increased ABA concentration and reduced fresh and dry mass in both caryopses and embryos. Fluridone did not affect fresh and dry mass. Addition of ABA to culture media slightly reduced media uptake by detached spikes. During desiccation, ABA and dry matter decreased in caryopses whereas embryos continued to accumulate both. After 2d, 95 % of Greer kernels exposed to fluridone germinated while only 80 % of Brevor kernels were germinated after 4 d. Culture of detached spikes in media amended with fluridone and ABA induced higher dormancy levels in Brevor than in Greer. Results from this study support the hypothesis that ABA may be involved in acquisition of dormancy as well as maintenance of dormancy in wheat kernels.