Reducing seed dormancy in Indian ricegrass [Oryzopsis hymenoides]

Abstract

Indian ricegrass [Oryzopsis hymenoides (Roem. and Schult.) Ricker] is an excellent native species for revegetation of coal and oil shale sites. However, inadequate germination due to a high seed dormancy results in poor stand development and limits its use. This paper presents the results of a series of experiments attempting to reduce the dormancy by weakening the lemma and palea by scarification of the seed covering. Four treatments (three mechanical and one concentrated sulfuric acid) were examined, alone and in combination with gibberellic acid. Three ages of seed were tested in the greenhouse, the laboratory and the field. Concentrated sulfuric acid and a modified commercial scarifier most effectively increased germination in the greenhouse; gibberellic acid enhanced germination of the younger, fresher seeds in this environment. A rubbing machine improved emergence in the field more than the other treatments. It was, however, only a modest improvement. Concentrated sulfuric acid decreased field emergence for all 3 ages of seed. Germination studies in the laboratory indicated that none of the treatments increased mortality.