Effects of light conditions and after‐ripening time on seed dormancy loss of Bromus diandrus Roth.

Abstract

Del Monte JP & Dorado J (2011). Effects of light conditions and after‐ripening time on seed dormancy loss of Bromus diandrus Roth. Weed Research51, 581–590.SummaryBromus diandrus is an emerging problem in barley crops in temperate climates, owing to its ability to adapt to certain farming techniques, as well as the absence of an efficient means of control. The aim of this study was to evaluate the germination of B. diandrus as a function of light conditions, time after ripening, temperature and water potential. Our results indicate that light conditions were the principal factor affecting germination and that seeds had negative photoblastism. Darkness modified the hydrotime parameters of the seeds somewhat, for example, by decreasing the values of Ψb and by favouring dormancy loss. The after‐ripening time significantly modified the hydrotime parameters of the seeds, causing Ψb to drift towards more negative values (greater dormancy loss) as the after‐ripening time increased. The combination of both variables explains the dormancy dynamics of this species in Mediterranean climates that are characterised by two distinct germination flushes, coinciding with two periods when soil humidity and temperature are not limiting. The first and main cohort of seedlings would emerge in autumn, originating from young buried seeds. A second cohort would emerge in the spring, from mature seeds on the surface of the soil.