15 research outputs found
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Nitrogen accumulation and acetylene reduction activity of native lupines on disturbed mountain sites in Colorado
Lupines are pioneering plants in many disturbed mountain habitats in Colorado. The purpose of this work was to determine if Lupinus argenteus, L. caudatus, and L. alpestris could be useful revegetation plants in a reclamation program. Paired soil samples from 33 disturbed sites supporting native lupines were used to determine if lupines increased the nitrogen content of the soil. Soil samples collected 10 cm from lupine tap roots averaged 13.8 mg kg-1 more exchangeable ammonium and 2.7 mg kg-1 more nitrate than soil samples collected 3 m from lupine plants. Field measured acetylene reduction rates of detached lupine nodules averaged 10.0 micromol ethylene g-1 nodule dry weight h-1 for L. argenteus and 17.3 micromol ethylene g-1 nodule dry weight h-1 for L. alpestris. Soil adjacent to lupines had higher levels of inorganic nitrogen than soils 3 m from lupine plants and lupines had the ability for biological nitrogen fixation as shown by the acetylene reduction assay, suggesting that native lupines are potentially useful revegetation plants in a reclamation program.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Reducing seed dormancy in Indian ricegrass [Oryzopsis hymenoides]
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.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Previous grazing or clipping affects seed of Indian ricegrass
Previous heavy grazing for more than 50 years, compared with protection from livestock grazing, in the semi-arid area of Chaco Canyon in the southwestern United States did not result in any significant decrease in seed production potential of Indian ricegrass [Oryzopsis hymenoides (Roem. and Schult.) Ricker]. There also were no significant differences in seed production between grazed and ungrazed collections of Indian ricegrass from the Chaco Canyon study site when transplanted and grown in a common garden. This indicated that long-term protection from livestock grazing probably had not genetically (ecotypically) altered seed production potential. Both grazed and ungrazed transplants of Indian ricegrass differed in seed production from the cultivars 'Paloma' and 'Nezpar'. Nezpar produced the greatest seed yield (312 kg/ha), while Paloma had the lowest yield (78 kg/ha). Defoliation about 1 June over a 2-year period reduced seed production and nitrogen fertilization did not increase seed yield. Previous grazing history had little effect on seed germination, but there were significant differences in germination among some collections and cultivars of Indian ricegrass. Germination was less than 5% for all entries. A tetrazolium viability test showed that seed of native strains were more viable than those of Paloma. Dormancy is a troublesome, but desirable, trait of Indian ricegrass seed for use in droughty areas.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Caryopsis Weight and Planting Depth of Blue Grama. II. Emergence in Marginal Soil Moisture
Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] has not been able to establish itself, or to be successfully planted, from seed on abandoned croplands of the Central Plains. The objectives of this study were to test blue grama plant material under limited moisture and develop methods for improving emergence and establishment of blue grama seedlings. Experiments were conducted in the greenhouse and at the Central Plains Experimental Range near Nunn, Colorado, with 3 accessions. Under limited moisture conditions in the greenhouse, seedlings emerged better from planting depths of 2.0 and 2.5 cm than from depths of 0.5, 1.0 or 1.5 cm. Higher caryopsis weight was associated with a significant increase in percentage emergence at all planting depths. Accession PM-K-1483 had greatest emergence, followed by 'Hachita' and 'Lovington'. Under favorable soil moisture conditions in the field (2 cm of water applied at planting dates in June and July 1981), deep planting resulted in decreased emergence. Averaged over all planting depths, percentage emergence increased nearly 2-fold with an increase in caryopsis weight from 39 to 59 mg/100. When soil moisture conditions were marginal (only 1 cm water added), satisfactory emergence was obtained only when high-weight seeds were planted at a depth of 2 cm. Soil at a planting depth of 1 cm dried quickly and prevented emergence. Genetic improvement of caryopsis weight combined with planting at depths of about 2.0 cm should improve the emergence and establishment of blue grama seedlings.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Caryopsis Weight and Planting Depth of Blue Grama. I. Morphology, Emergence, and Seedling Growth
Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] has been difficult to establish from seed on disturbed areas of the Central Plains. The objective of this study was to investigate the relationship of caryopsis weight, planting depth, and genetic variability on seedling emergence of blue grama. Two experiments were conducted in the greenhouse under favorable moisture conditions with 3 accessions and various combinations of caryopsis weight and planting depth. Measurements included rate of germination and emergence as an index, percentage emergence, shoot length, shoot weight, seminal root length, coleoptile length, subcoleoptile internode length and weight, adventitious root weight, and longest adventitious root length. The length of the subcoleoptile internode increased in response to greater planting depth but weight per unit length decreased. If this indicates a decrease in internode diameter it could decrease the rate of water transport through the internode. Deep plantings were not advantageous to emergence or seedling growth under favorable soil moisture conditions and caused a delay in emergence and decreased percentage emergence, shoot weight, and adventitious root weight. High caryopsis weight was associated with an increase in emergence, weight per unit length of the subcoleoptile internode, coleoptile length, shoot weight, and adventitious root weight. Therefore, high caryopsis weight is advantageous in the deep planting of blue grama seeds and allows seeds to be planted deeper to take advantage of moisture for germination and emergence.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202