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Indian ricegrass [Olyzopsis hy#nt?noties (Roem. and Schuit.) 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 paiea by scarification of the seed covering. Four treatments (three mechanical nnd 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; gibbereilic acid enhanced germination of the younger, fresher seeds in this environment. A rubbing machine improved emergence in the tieid more than the other treatments. It was, however, only a modest improvement. Concentrated sulfuric acid decreased field emergence for ail 3 ages of seed. Germination studies in the laboratory indicated that none of the treatments increased mortality. Indian ricegrass [Oryzopsis hymenoides Roem. and Schult.) Ricker] is a native perennial bunchgrass adapted to a wide range of dry, infertile habitats. It is common on the foothills, plateaus, and plains of the western United States and Canada; it thrives in well-aerated rocky or sandy soils. The mature plant is a palatable and nutritious forage crop (Rogler 1960). The seeds, high in protein and fat content, are a popular feed of livestock and rodents (Hafenrichter et al. 1968). The plant tolerates heavygrazing(Stoddart and Wilkinson 1938) and is capable of controlling wind erosion (Bohmont and Lang 1957). These qualities make Indian ricegrass an important prospect for revegetation of coal and oil shale sites. However, its use for this has been limited because an inherent seed dormancy results in an inadequate germination and poor stand establishment. Huntamer (1934) and Toole (1940) found 2 dormancy mechanisms responsible for the low germination: an indurate lemma and palea and a dormant embryo. They established that seed treatments which weaken the hard seed covering (the lemma and palea) improve germination. These authors. as well as Stoddart and Wilkinson (1938), Plummer and Frischknecht (1952), and McDonald and Khan (1977) concluded that scarification with formulations of sulfuric acid was’ the most effective means of weakening the seed covering and increasing germination. Toole (i940) also found that prechilling for 28 days increased germination. Plummer and Frischknecht (1952) showed that a stratification treatment helped overcome embryo dormancy. Clark and Bass (1970) established that alternating temperatures also promoted germination. Huntamer (1934) and Toole (1940) realized that aging alone reduced dormancy. Rogler (1960) tested the effect of age and Authors are, mspectively, graduate research assistant, undergraduate student, and associate professor in the Department of Agronomy, Colorado State University, Fort Collins 80523. Research was supported by contract DE-AS02-76EVO4018 from the U.S. Dcoartment of Enernv and the Colorado State University Experiment Station. Experiment Station Journal No. 2662. Manuscript received July 23, 1981. JOURNAL OF RANGE MANAGEMENT 39(2). March 1983 confirmed that germination increased with time, but only to a point (approximately 6 years), after which it decreased. McDonald and Khan (1977) suggested that it is the embryo dormancy that is temporary and its effect decreases significantly after a year in storage. Mechanical scarification also increases germination of the seed. Huntamer (1934) and Stoddart and Wilkinson (1938) reduced dormancy by removing the lemma and palea with a knife. Huntamer (1934), Toole (1940) and Plummer and Frischknecht (1952) rubbed the seed with sandpaper and emery paper. Toole (1940) also rolled seeds in a metal box with gravel to break the seed coat. Although successful in improving germination, both methods damaged the embryos of some seeds. McDonald and Khan (1977) included hormones in their tests of methods to reduce dormancy. They found abscisic acid inhibited germination while gibberellic acid and kinetin stimulated it. Methods of improving Indian ricegrass germination have thus been studied since 1934 (Huntamer 1934). Todate, sulfuricacid to weaken the seed covering or exposure to moist, cold temperatures have been the most successful methods for enhancing germination of Indian ricegrass seed. This paper presents the results of a study of 9 mechanical, acid, and hormonal treatments. The effect of time was studied with seed of 3 ages. Furthermore, the treatments were tested in the greenhouse, the field, and germination boxes in the laboratory, to evaluate their relationship with environment. Materials and Methods Seed of the Warner Farm strain was collected in 1975,1976, and 1977 near Greeley, Colo., in an attempt to represent different ages of seed. After being cleaned and graded, seed from each year was divided into 10 equal lots. One lot was left untreated as a control, each of the 9 remaining lots was then treated by one of the following methods: (1) commercial scarifier, (2) tumbler, (3) rubbing machine, (4) sulfuric acid (5) gibberellic acid (GAs), (6) commercial scarifier plus G&I, (7) tumbler plus Gk, (8) rubbing machine plus GAs, and (9) sulfuric acid plus GAs. The first 3 treatments, mechanical scarification techniques, attempted to increase germination by scratching the seed covering, weakening it. They are modeled after methods commonly used in the seed industry, especially with legumes. The fourth treatment, concentrated sulfuric acid, was used to weaken the seed covering chemically and thus decrease dormancy. The final 5 treatments tested the ability of GA3 to counteract abscisic acid, alone and in combination with the first 4 treatments. The commercial scarifier treatment used a Forsberg Line scarifier which had rotating batts propelling the seed against 40 grade sandpaper. One and a half minute treatments with a variable rheostat to maintain the batts’ speed at 426 f 25 rpm minimized embryo damage and maximized scarification. The tumbler scarifier was modeled after a lapidary tumbler, using a 3/&inch drill for a motor and a metal canister lined with 80 grade sandpaper for a tumbling chamber. Again variable rheostat kept the speed at an optimum 70 f 5 rpm. A i-hour treatment was determined to give good scarification with minimal damage.

Reducing Seed Dormancy in Indian Ricegrass [Oryzopsis hymenoides]