分类： 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间： 2016-05-04
Jon P. McCalmont
Astley Hastings
Niall P. McNamara
Goetz M. Richter
Paul Robson
Iain S. Donnison
John Clifton-Brown
摘要： Planting the perennial biomass crop Miscanthus in the UK could offset 213Mtoileq.yr1, contributing up to 10% of current energy use. Policymakers need assurance that upscaling Miscanthus production can be performed sustainably without negatively impacting essential food production or the wider environment. This study reviews a large body of Miscanthus relevant literature into concise summary statements. Perennial Miscanthus has energy output/input ratios 10 times higher (47.32.2) than annual crops used for energy (4.70.2 to 5.50.2), and the total carbon cost of energy production (1.12gCO2-Ceq.MJ1) is 2030 times lower than fossil fuels. Planting on former arable land generally increases soil organic carbon (SOC) with Miscanthus sequestering 0.72.2MgC4-Cha1yr1. Cultivation on grassland can cause a disturbance loss of SOC which is likely to be recovered during the lifetime of the crop and is potentially mitigated by fossil fuel offset. N2O emissions can be five times lower under unfertilized Miscanthus than annual crops and up to 100 times lower than intensive pasture. Nitrogen fertilizer is generally unnecessary except in low fertility soils. Herbicide is essential during the establishment years after which natural weed suppression by shading is sufficient. Pesticides are unnecessary. Water-use efficiency is high (e.g. 5.59.2gaerial DM (kgH2O)1, but high biomass productivity means increased water demand compared to cereal crops. The perennial nature and belowground biomass improves soil structure, increases water-holding capacity (up by 100150mm), and reduces run-off and erosion. Overwinter ripening increases landscape structural resources for wildlife. Reduced management intensity promotes earthworm diversity and abundance although poor litter palatability may reduce individual biomass. Chemical leaching into field boundaries is lower than comparable agriculture, improving soil and water habitat quality.
分类： 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间： 2016-05-04
Christopher Lyndon Davey
Laurence Edmund Jones
Michael Squance
Sarah Jane Purdy
Anne Louise Maddison
Jennifer Cunniff
Iain Donnison
John Clifton-Brown
摘要： Miscanthus is a rhizomatous C4 grass of great interest as a biofuel crop because it has the potential to produce high yields over a wide geographical area with low agricultural inputs on marginal land less suitable for food production. At the moment, a clonal interspecific hybrid Miscanthusgiganteus is the most widely cultivated and studied in Europe and the United States, but breeding programmes are developing newer more productive varieties. Here, we quantified the physiological processes relating to whole season yield in a replicated plot trial in Wales, UK. Light capture and conversion efficiency were parameterized for four carefully selected genotypes (M.sinensis, M.sacchariflorus and Miscanthusgiganteus). Differences in the canopy architecture in mature stands as measured by the extinction coefficient (k) were small (0.550.65). Sensitivity analysis on a mathematical model of Miscanthus was performed to quantify the accumulative intercepted photosynthetically active radiation (iPAR) in the growing season using (i) k, (ii) variation in the thermal responses of leaf expansion rate, (iii) base temperature for degree days and (iv) date start of canopy expansion. A 10% increase in k or leaf area per degree day both had a minimal effect on iPAR (3%). Decreasing base temperature from 10 to 9C gave an 8% increase in iPAR. If the starting date for canopy expansion was the same as shoot emergence date, then the iPAR increases by 12.5%. In M.giganteus, the whole season above ground and total (including below ground) radiation-use efficiency (RUE) ranged from 45% to 37% higher than the noninterspecific hybrid genotypes. The greater yields in the interspecific hybrid M.giganteus are explained by the higher RUE and not by differences in iPAR or partitioning effects. Studying the mechanisms underlying this complex trait could have wide benefits for both fuel and food production.
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