Seed dormancy mechanisms in diploid wheat (Triticum tauschii (Coss.) Schmalh.)

© 2004 Keith Trevor GatfordWheat is the world’s third largest food crop, and is relied upon as a food source by millions of people. Securing the supply of wheat is a problem because it is susceptible to many biotic and abiotic factors that limit production. One such factor, sprouting of the grain in the head, because of untimely rainfall prior to harvest, is a substantial problem worldwide. Pre-harvest sprouting has a significant impact on wheat growers, who suffer considerable economic hardship as a result of yield loss during harvesting and subsequent downgrading of their sprouted crops. Wheat processors are also affected by this problem, because sprouted grain has significantly altered chemical properties, making it unsuitable for its intended purpose, and often rendering it suitable for animal consumption only. This study investigated mechanisms of dormancy, in the diploid wheat Triticum tauschii (Coss.) Schmalh., to assess their suitability for use in hexaploid (bread) wheat to prevent pre-harvest sprouting. A soluble germination inhibitor was found in the bracts (palea, lemma and glumes) surrounding the grain of T. tauschii. Fractionation of an aqueous extract from the bracts, by HPLC, identified vanillic acid as being likely to be involved in this inhibition. Further analysis of the extract also identified a strong anti-oxidant capacity, indicating that part of the inhibition of germination may arise from the prevention of oxygen reaching the embryo