共查询到18条相似文献,搜索用时 156 毫秒
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中缅边境地区稀有魔芋品种资源研究初探 总被引:7,自引:3,他引:4
生长在中缅边境地区的稀有魔芋品种具有与国内外已报道过的品种迥然不同的繁殖特点。该品种除具有魔芋多糖含量高、分子量大和粘度值高的特点外,还具有地下部分的肉质根(球);不同的是各枝叶交叉点上生长着可供繁殖的小球茎。这一稀有品种至今尚未见报道。 相似文献
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通过种子萌发试验,研究了光照、温度、赤霉素对迎阳报春种子萌发的影响,同时对其种子形态进行了观测.结果表明,迎阳报春成熟种子为黄褐色,呈不规则卵圆形或多面形,种子细小,千粒重为89.52±0.25mg.种子萌发的适宜温度为20℃,对光敏感,光照条件下萌发率较高,萌发进程较快;种子经赤霉素处理后,萌发持续时间缩短,但对种子最终发芽率、发芽势影响不显著. 相似文献
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以紫苏茎、叶、花序为供体,木香薷种子为受体,采用3×5二因素完全随机试验设计和室内生物测定法研究了紫苏水浸液对木香薷种子萌发及幼苗生长的化感作用。结果表明:1供体类型和水浸液浓度对木香薷种子的发芽势、发芽指数、发芽率、成苗率、胚根长度和胚轴长度均有极显著影响。供体化感作用强弱顺序是:叶片>花序>茎,并有高抑制低促进的浓度效应。2紫苏茎、叶、花序的水浸液主要是通过抑制木香薷胚根的伸长来抑制种子萌发与幼苗生长。3叶片淋溶是紫苏释放化感物质的主要途径之一。 相似文献
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为研究超声处理对污泥消化效率的影响,笔者在大坦沙污水处理厂做了现场对比试验。所用的污泥分别为经过和未经过超声处理的污泥。试验结果显示,超声处理可以显著缩短消化罐的调试周期并提高消化效率,不同的混合比例可以使产气率提高30%~60%。 相似文献
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J. H. Krishna G. F. Arkin J. R. Martin 《Journal of the American Water Resources Association》1987,23(6):1057-1061
ABSTRACT: The current increase in the demand for water by municipal, industrial, and other users is likely to result in approximately one-third less water being available for agricultural use in Texas by the year 2000. As water supplies diminish, the rainfall excess needs to be used more efficiently. Large amounts of runoff occur in the eastern part of Texas that could be collected in small impoundments and utilized for crop production. Farmers in water-surplus basins or subbasins can apply for a permit to divert surface water into small on-farm impoundments to be used for supplemental irrigation. The costs for runoff collection and two supplemental irrigations, which amount to a total of 4 in./yr., are estimated to be approximately $60/acre/year. Depending upon the crop produced, the estimated increase in gross income from supplemental irrigation ranges from about $80 to more than $100 per acre annually. 相似文献
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石油污染土壤中石油含量对玉米的影响 总被引:27,自引:1,他引:26
为了弄清石油污染土壤中石油类对农作物的影响,吉林油田进行了一年的田间玉米种植试验。在不同浓度水平,分别对玉米出苗率、可见外观特性、百粒重、产量和品质进行了较系统的观察、监测、类比分析。结果表明,土壤中石油含量的不同,对玉米生长过程各项指标有不同的影响。并找出吉林油田土壤—玉米系统中影响玉米生长及其产量的土壤临界含油量。 相似文献
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粮食估产的“通道-概率”理论:把属于最近通道的历年来的产量划分为5个气候年型通道,即丰产年、偏丰年、平产年、偏欠年、欠产年;计算产量出现在5个气候年型中的频率作为概率使用,估产年的初始估产值等于预测年各通道内平均产量与概率之积的和;估产值等于初始估产值与气候年型修正参数之积,专家根据当年气候条件和作物长势实时确定修正参数。预报单元为全国、省和县。应用结果表明:国家尺度上不需要修正,省和县级尺度需要气候年型参数修正;预测误差在3%以内;所述估产理论严谨、方法简单,参数少,参数来自原始数据本身和专家经验,易于推广使用。 相似文献
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Anna Bateman Dan van der Horst David Boardman Arun Kansal Cynthia Carliell-Marquet 《Resources, Conservation and Recycling》2011,55(12):1146-1153
Every year 90 million tonnes of housed livestock manures are produced in the UK. This is a valuable reservoir of global phosphorus (P) and a point in the cycle where it is vulnerable to being lost from the terrestrial system. Improved manure management for the effective reuse of phosphorus is vital to simultaneously tackle a major source of water pollution and reduce our dependence on imported fertilisers. This paper quantifies, for the first time, the spatial and temporal challenges of recycling the required amount of manure P from areas of livestock production to areas of crop production in eight regions of England. The analysis shows that England has a P deficit and therefore the capacity to fully utilise the manure P on arable land, but that uneven spatial distribution of livestock poses a significant challenge to closing the P loop in agriculture. Two of the eight regions were shown to have surplus manure P, with the remaining six regions having P deficits, indicating that an annual export of 4.7 thousand tonnes P (2.8 million tonnes manure) must take place from the west to the east of the country each year to balance P supply and demand. Moreover, housed manure production peaks between October and February, requiring an excess of 23.0 thousand tonnes P (15 million tonnes manure) to be stored until it can be used for crop fertilisation from March onwards. The results demonstrate the scale of the challenge in managing manure P in an agricultural system that has separated livestock production from crop production, a pattern that is echoed throughout the developed world. To overcome the spatial and temporal challenges, a logistical system is recommended that will balance the nutrient potential (nitrogen and P content and availability) and pollution potential (eutrophication, greenhouse gas emissions, particulates and nitrous oxide from transport) for cost-effective and environmentally compatible redistribution of manure P from areas of surplus to areas of deficit, when required. 相似文献
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Ahmad K. Hegazy Mahmoud A. Medany Hanan F. Kabiel Mona M. Maez 《Natural resources forum》2008,32(4):316-326
This study focuses on the management of the local agroecosystems in order to adapt planting or sowing practices for the projected climate change scenarios. It is projected that there will be increased air temperature throughout all four seasons in the coming 100 years, from the southern towards the northern parts of Egypt. The objective of this study is to investigate the influence of that increased air temperature on the spatial and temporal distribution of four of the major economic crops in Egypt. The study species are cotton (Gossypium barbadense L., cv. Giza 89), wheat (Triticum aestivum L., cv. Gemiza 9), rice (Oryza stiva L., cv. Sakha 101) and maize (Zea mays L., cv. Hybrid 10). Optimum air temperature allowing maximum growth for each of the study crop cultivars and the current and projected air temperature patterns in the future years were used for projection of the seasonal and crop distribution maps in the years 2005, 2025, 2050, 2075 and 2100. Results showed that sowing dates of a target crop may be managed in order to allow maximum predicted planting area in the same region. The current maximum area suitable for planting the Cotton crop in Egypt (104 thousand Fadden/year; one Fadden = 0.96 hectare or 0.42 acre) showed few variations over the coming hundred years. In this case, the sowing dates should be changed from the hotter months (February to April) to the cooler months (January to February). Alternatively, a great reduction in the area planted by Wheat crop was predicted in the coming 100 years. Despite the early planting, a reduction of about 147 thousand Fadden/year was projected by the year 2075. On the other hand, with earlier sowing dates, the maximum areas that are planted by Rice and Maize may not be greatly affected by the projected increase in air temperature. 相似文献
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Net global warming potential and greenhouse gas intensity in irrigated cropping systems in northeastern Colorado 总被引:25,自引:0,他引:25
The impact of management on global warming potential (GWP), crop production, and greenhouse gas intensity (GHGI) in irrigated agriculture is not well documented. A no-till (NT) cropping systems study initiated in 1999 to evaluate soil organic carbon (SOC) sequestration potential in irrigated agriculture was used in this study to make trace gas flux measurements for 3 yr to facilitate a complete greenhouse gas accounting of GWP and GHGI. Fluxes of CO2, CH4, and N2O were measured using static, vented chambers, one to three times per week, year round, from April 2002 through October 2004 within conventional-till continuous corn (CT-CC) and NT continuous corn (NT-CC) plots and in NT corn-soybean rotation (NT-CB) plots. Nitrogen fertilizer rates ranged from 0 to 224 kg N ha(-1). Methane fluxes were small and did not differ between tillage systems. Nitrous oxide fluxes increased linearly with increasing N fertilizer rate each year, but emission rates varied with years. Carbon dioxide efflux was higher in CT compared to NT in 2002 but was not different by tillage in 2003 or 2004. Based on soil respiration and residue C inputs, NT soils were net sinks of GWP when adequate fertilizer was added to maintain crop production. The CT soils were smaller net sinks for GWP than NT soils. The determinant for the net GWP relationship was a balance between soil respiration and N2O emissions. Based on soil C sequestration, only NT soils were net sinks for GWP. Both estimates of GWP and GHGI indicate that when appropriate crop production levels are achieved, net CO2 emissions are reduced. The results suggest that economic viability and environmental conservation can be achieved by minimizing tillage and utilizing appropriate levels of fertilizer. 相似文献
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Thomas V. Armentano 《Environmental management》1984,8(6):529-538
Large but feasible increases that have been projected for the production of wood energy in the United States can be expected to significantly alter the current carbon storage patterns in US forest vegetation. The 1976 net wood increment left after forest cutting equals about 136 × 106 tons of carbon/year, with about 60% of the increment found in merchantable trees, and the remainder in nonmerchantable components.Achieving 5–10 quads of wood energy beyond 1976 levels by the year 2010 can significantly change current carbon storage patterns with the magnitude of change dependent on the extent of residue harvest to meet energy goals, and the rate of future forest growth. Complete loss of the apparent net wood increment is a possible outcome.Although the future growth and harvest situation cannot be known now, a range of possible scenarios suggests that US forests in the year 2010 will store much less carbon than today, thus significantly changing their role in the global carbon cycle. 相似文献
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Monica Goigel Turner 《Environmental management》1987,11(2):237-247
Land use since 1935 was quantified for Georgia, USA, and for a sample of 20 counties from the major physiographic regions within the state. Statistical data on crop production, pasture productivity, and forest growth were used to estimate net primary production. Appropriate harvest indices (ratio of crop yield to total plant production) were used to correct crop yield data for different decades. Net primary production (NPP) of the Georgia landscape increased from 2.5 to 6.4 tonnes/ha from 1935 to 1982, but varied considerably among land uses and physiographic regions. NPP in the piedmont and mountains reached a plateau between 1960 and 1982, but the upper and lower coastal plains showed a continued linear increase in NPP. In all regions, NPP rose most between 1960 and 1982, coinciding with increases in inputs such as fertilizer and irrigation. Natural ecosystem NPP for Georgia is approximately 16–18 tonnes/ha, and the estimated actual NPP is thus considerably less than the potential. Spatial and temporal patterns of NPP may be a useful basis for evaluating the biological performance of a landscape. 相似文献