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Virgatum L. (virgatum + l)
Kinds of Virgatum L. Selected AbstractsA quantitative review comparing the yield of switchgrass in monocultures and mixtures in relation to climate and management factorsGCB BIOENERGY, Issue 1 2010DAN WANG Abstract Switchgrass (Panicum virgatum L.), a US Department of Energy model species, is widely considered for US biomass energy production. While previous studies have demonstrated the effect of climate and management factors on biomass yield and chemical characteristics of switchgrass monocultures, information is lacking on the yield of switchgrass grown in combination with other species for biomass energy. Therefore, the objective of this quantitative review is to compare the effect of climate and management factors on the yield of switchgrass monocultures, as well as on mixtures of switchgrass, and other species. We examined all peer-reviewed articles describing productivity of switchgrass and extracted dry matter yields, stand age, nitrogen fertilization (N), temperature (growing degree days), and precipitation/irrigation. Switchgrass yield was greater when grown in monocultures (10.9 t ha,1, n=324) than when grown in mixtures (4.4 t ha,1, n=85); yield in monocultures was also greater than the total yield of all species in the mixtures (6.9 t ha,1, n=90). The presence of legume species in mixtures increased switchgrass yield from 3.1 t ha,1 (n=65) to 8.9 t ha,1 (n=20). Total yield of switchgrass-dominated mixtures with legumes reached 9.9 t ha,1 (n=25), which was not significantly different from the monoculture yield. The results demonstrated the potential of switchgrass for use as a biomass energy crop in both monocultures and mixtures across a wide geographic range. Monocultures, but not mixtures, showed a significant positive response to N and precipitation. The response to N for monocultures was consistent for newly established (stand age <3 years) and mature stands (stand age ,3 years) and for lowland and upland ecotypes. In conclusion, these results suggest that fertilization with N will increase yield in monocultures, but not mixtures. For monocultures, N treatment need not be changed based on ecotype and stand age; and for mixtures, legumes should be included as an alternative N source. [source] Optimization of culture conditions for plant regeneration of Panicum spp. through somatic embryogenesisGRASSLAND SCIENCE, Issue 1 2010Mi-Suk Seo Abstract We developed a rapid and efficient shoot regeneration system for Panicum spp. by adjusting the regeneration medium and studying the responses of different genotypes and the influence of explant types (mature seed, immature embryo and shoot apex). We used Panicum meyerianum (Nees) and Panicum longijubatum (Stapf) which were shown to perform well, to select the optimal medium for shoot regeneration. The highest frequency of shoot regeneration was obtained on Murashige and Skoog medium supplemented with 30 g L,1 maltose and 1 mg L,1 N-phenyl-N,-[(1,2,3-thidiazol-5-yl) urea]. The callus formed green spots after 1 week of culture and showed primary green shoots after 2 weeks. In this system, the calli derived from mature seed of nine Panicum genotypes showed large variation in shoot regeneration ability: from 0 to 69.9% in the frequency of shoot formation and from 0 to 8.4 in the number of shoots per callus. Guineagrass (Panicum maximum Jacq.) showed no ability and switchgrass (Panicum virgatum L.) showed low ability to regenerate from mature seed-derived calli; however, both were able to be regenerated from immature embryos and calli derived from shoot apices. We developed an efficient protocol for high shoot regeneration of various Panicum genotypes which provides a foundation for efficient tissue culture and genetic improvement of Panicum. [source] Establishing native plants on newly-constructed and older-reclaimed sites along West Virginia highwaysLAND DEGRADATION AND DEVELOPMENT, Issue 4 2008J.G. Skousen Abstract Many state highway departments in the USA must use native plants for revegetating roadsides. We conducted two field studies in West Virginia to assess native plant establishment under two different conditions. On newly-constructed sites, native species were seeded alone or combined with non-native species. On older roadsides, native species were seeded in disturbed existing vegetation. In the first study, we used four seed mixtures comprised of seeds of native and non-native species, and two N-P-K fertilizer treatments at three newly-constructed sites. Native, warm-season grasses were slow to establish and only contributed 25 per cent cover in some plots after three years. Indiangrass (Sorghastrum nutans [L.] Nash), big bluestem (Andropogon gerardii Vitman), Brown-Eyed Susan (Rudbeckia triloba L.), and wild senna (Cassia hebecarpa Fernald) were the only seeded native species found. Fertilizer at 150,kg,ha,1 of 10-20-10 showed little influence on increasing plant cover. In the second study, we disturbed three different-aged established stands of vegetation composed of tall fescue (Festuca arundinacea Screb.) and crownvetch (Coronilla varia L.) by mowing, herbicide, or tillage, and native plants were seeded with and without fertilizer. Native cover was <10 per cent in all plots during the first year, but greatly increased by the second year to as much as 45 per cent in tilled plots, indicating that disturbance was necessary for natives to become important contributors within 2 years. Only switchgrass (Panicum virgatum L.), little bluestem (Andropogon scoparius Vitman), partridge pea (Chamaecrista fasciculate Michx.), and Brown-Eyed Susan were observed in plots. Fertilizer at 300,kg,ha,1 of 10-20-10 did not increase native plant cover on these sites. Based on our results, introducing or increasing the cover of native species along roadsides requires (1) reducing competition from non-native species, and (2) longer time periods for these slower-establishing species to be observed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Productivity and Subordinate Species Response to Dominant Grass Species and Seed Source during RestorationRESTORATION ECOLOGY, Issue 5 2010Brian J. Wilsey Grasses can be important regulators of species diversity and ecosystem processes in prairie systems. Although C4 grasses are usually assumed to be ecologically similar because they are in the same functional group, there may be important differences among species or between seed sources that could impact restorations. I tested whether C4 grass species identity, seed source, or grass species richness scales to influence aboveground net primary productivity (ANPP), resistance to weed invasion, or establishment of subordinate prairie species during restoration. Plots in western Iowa, United States, were planted with equal-sized transplants of one of five common grass species (Panicum virgatum L., Sorghastrum nutans (L.) Nash, Andropogon gerardii Vitman, Schizachyrium scoparium (Michx.) Nash, and Bouteloua curtipendula (Michx.) Torrey) either from local seed or from cultivar seed sources. These plots were compared to plots containing all five species in mixture and to nonplanted plots. Differences in ANPP were found among species but not between cultivars and noncultivars or between monocultures and mixtures. Panicum virgatum, S. nutans, and S. scoparium were more productive than A. gerardii and B. curtipendula. Weed invasion was much higher when plots were not planted with grasses. Schizachyrium scoparium allowed greater establishment of subordinant prairie species than all other focal grass species. There were two separate mechanisms by which grasses suppressed prairie species establishment either (1) by growing tall and capturing light or (2) by quickly filling in bare space by spreading horizontally through rhizome growth in short species. These results suggest that high ANPP can be found with noncultivar plantings during the first 2 years after planting and that subordinate species establishment is most likely when shorter bunchgrasses such as S. scoparium are dominant. [source] Large-scale production, harvest and logistics of switchgrass (Panicum virgatum L.) , current technology and envisioning a mature technologyBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 2 2009Shahab Sokhansanj Abstract Switchgrass (Panicum virgatum L.) is a promising cellulosic biomass feedstock for biorefineries and biofuel production. This paper reviews current and future potential technologies for production, harvest, storage, and transportation of switchgrass. Our analysis indicates that for a yield of 10 Mg ha,1, the current cost of producing switchgrass (after establishment) is about $41.50 Mg,1. The costs may be reduced to about half this if the yield is increased to 30 Mg ha,1 through genetic improvement, intensive crop management, and/or optimized inputs. At a yield of 10 Mg ha,1, we estimate that harvesting costs range from $23.72 Mg,1 for current baling technology to less than $16 Mg,1 when using a loafing collection system. At yields of 20 and 30 Mg ha,1 with an improved loafing system, harvesting costs are even lower at $12.75 Mg,1 and $9.59 Mg,1, respectively. Transport costs vary depending upon yield and fraction of land under switchgrass, bulk density of biomass, and total annual demand of a biorefinery. For a 2000 Mg d,1 plant and an annual yield of 10 Mg ha,1, the transport cost is an estimated $15.42 Mg,1, assuming 25% of the land is under switchgrass production. Total delivered cost of switchgrass using current baling technology is $80.64 Mg,1, requiring an energy input of 8.5% of the feedstock higher heating value (HHV). With mature technology, for example, a large, loaf-collection system, the total delivered cost is reduced to about $71.16 Mg,1 with 7.8% of the feedstock HHV required as input. Further cost reduction can be achieved by combining mature technology with increased crop productivity. Delivered cost and energy input do not vary significantly as biorefinery capacity increases from 2000 Mg d,1 to 5000 Mg d,1 because the cost of increased distance to access a larger volume feedstock offsets the gains in increased biorefinery capacity. This paper outlines possible scenarios for the expansion of switchgrass handling to 30 Tg (million Mg) in 2015 and 100 Tg in 2030 based on predicted growth of the biorefinery industry in the USA. The value of switchgrass collection operations is estimated at more than $0.6 billion in 2015 and more than $2.1 billion in 2030. The estimated value of post-harvest operations is $0.6,$2.0 billion in 2015, and $2.0,$6.5 billion in 2030, depending on the degree of preprocessing. The need for power equipment (tractors) will increase from 100 MW in 2015 to 666 MW in 2030, with corresponding annual values of $150 and $520 million, respectively. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source] | |||||||||||||