969 resultados para corn rootworm
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The Biogeography Branch’s Sampling Design Tool for ArcGIS provides a means to effectively develop sampling strategies in a geographic information system (GIS) environment. The tool was produced as part of an iterative process of sampling design development, whereby existing data informs new design decisions. The objective of this process, and hence a product of this tool, is an optimal sampling design which can be used to achieve accurate, highprecision estimates of population metrics at a minimum of cost. Although NOAA’s Biogeography Branch focuses on marine habitats and some examples reflects this, the tool can be used to sample any type of population defined in space, be it coral reefs or corn fields.
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The Biogeography Branch’s Sampling Design Tool for ArcGIS provides a means to effectively develop sampling strategies in a geographic information system (GIS) environment. The tool was produced as part of an iterative process of sampling design development, whereby existing data informs new design decisions. The objective of this process, and hence a product of this tool, is an optimal sampling design which can be used to achieve accurate, high-precision estimates of population metrics at a minimum of cost. Although NOAA’s Biogeography Branch focuses on marine habitats and some examples reflects this, the tool can be used to sample any type of population defined in space, be it coral reefs or corn fields.
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玉米(Zea mays L.)是我国十分重要粮食、饲料和工业原料作物,种植区域覆盖我国大部分农业区。随着玉米品种改良和新栽培技术的应用,我国玉米产量大幅度增加。自1950s以来,我国玉米产量递增幅度为126kg/hm2/yr。在玉米产量提高过程中,单叶光合作用与产量之间存在什么样的关系?当代玉米品种的品质和养分利用效率如何?高密度种植条件下是否存在“根系拥挤”及如何调控等。为探讨上述科学问题,本研究选择中国北方常见的大田玉米品种,在高肥力自然光照条件下,探讨玉米高产优质栽培过程中生理生态特征的变化趋势,以指导科学育种和栽培。主要研究结果如下: 1)光合与产量的演变我国 1950s、1970s、1990s等不同年代推广的玉米品种中,当代品种叶片光合速率高且高值持续期长,光合色素叶绿素a、叶绿素b、类胡萝卜素等的含量高且持续时间长,与光合有关的蒸腾速率(E.)、细胞间隙CO2浓度(Ci.)、气孔导度(gs)等也有较大改良,中下部叶片尤其明显;在生育后期,当代品种具有更高的光合优势。老品种饱和光合速率(Psat)在灌浆期下降,并非RuBPCase 和PEPCase的活性降低,而是由于叶绿素含量和可溶性蛋白含量的降低。在花后期间,由于PS2功能的下降,造成了光合能力下降,而现代品种的PS2 功能在衰老前一致保持旺盛状态。 老品种光合特征对缺氮的反应表现更敏感。花后缺氮光合作用下降是非气孔限制的,因为气孔导度和胞间CO2浓度没有发生明显的变化。其主要原因是缺素造成老品种叶片早衰,叶绿素含量、可溶性蛋白含量、PEP羧化酶活性下降。现代品种表现较强的抗衰老能力,其N素利用效用高于老品种。我国玉米产量的大幅度提高在很大程度上应归功于叶片光合性能的改良。 随玉米品种更替,群体光合速率增强,群体光合衰减率降低,呼吸消耗所占总光合的百分率下降。灌浆期当代品种中下部叶片的群体光合速率明显高于老品种。种植密度是影响玉米群体光合速率的主要因素,在高中低三种密度条件下,当代品种均有较高的群体光合速率,表现出耐密性强、适应性广、源足库大、产量高的特点。 2)高油玉米的产量受到叶源大小和叶源活力的双重限制在 1.5 株/m2密度下,与普通玉米相比较,高油玉米单株籽粒产量显著低于普通玉米,产量构成中穗粒数差异不显著,千粒重较低(P<0.01);两类型玉米的单株库容量相当,高油玉米籽粒灌浆速率小,籽粒充实度低,单粒重对叶源相对减少(剪叶)或相对增多(疏库)的反应比普通玉米更为敏感,其产量受到同化产物供应(叶源)相对不足的限制。高油玉米授粉后的叶面积、叶面积持续期小,叶片含氮量和光合速率较低,说明高油玉米的产量受到叶源活力(光合速率)小和叶源数量少的双重限制。 3)我国北方玉米品种的个体产量潜力、氮素利用效率及籽粒与秸秆粗蛋白质含量在充分发挥个体生产潜力的低密度条件下,我国北方1990s 以来大面积种植的50个玉米主栽品种中,个体产量潜力和氮素利用效率高度正相关(P=0.01),而子粒千粒重与NUE 呈显著性负相关(P=0.002)。对玉米产量和氮素利用效率进行分层聚类,可将北方玉米品种划分为高产高NUE 型、低产低NUE 型和中间型,高产高NUE 型玉米品种相对较少,仅占24%。籽粒粗蛋白质含量(CPC)与秸秆CPC 相关性不显著(P>0.05)。对籽粒和秸秆的CPC 进行分层聚类,将北方玉米品种划分为籽粒高秸秆低型、籽粒与秸秆双低型和籽粒与秸秆双高型,CPC 双高型品种相对较少,仅占20%。 4)玉米根系拥挤效应对产量影响的生理生态机制及其调控随玉米品种更替根系的空间分布呈“横向紧缩,纵向延伸”的特点。当代三类型玉米根系分布特性与株型、穗型相关。紧凑型品种根系分布深,下层根系所占比率大,适合密植,群体产量潜力大;平展大穗型品种根量多,分布较浅,在低密度下可获得较高的个体生产力,但不适合密植,群体产量潜力小。 “根系拥挤”显著影响玉米产量,减小根系横向伸展空间,下层土壤中的根系分配比率增多。在地上部充分生长条件下,紧凑型品种横向空间为30-50cm即可满足要求,平展型品种大于50cm;紧凑型品种对纵向空间受限制的反应更为敏感,平展型品种对横向空间受限制的反应更为敏感。“根系拥挤”影响根系活性、分布、氮素吸收利用和花后光合与14C同化物的分配。 在根系受限制条件下,增施肥料产量提高,根系总重增加,增加了根系在深层土壤(60-100cm)中的根系比率,显著增加了根系的TTC 还原量、SOD、CAT、POD活性。土壤加沙,根量减少,但根系TTC 还原量增加、产量提高,提高幅度以大穗型品种更为显著。 随种植密度增加耕层根系密度与群体产量同步增大,各类品种均在最高根系密度下获得最高产量。根系负荷的籽粒产量潜力三类型品种存在极大差异,在一定范围内增大种植密度,根系伸展空间减小,群体产量提高,紧凑大穗型品种产量最高,品种的耐密性是限制根系负荷籽粒产量潜力的主导因素。因此,培育株型紧凑、耐密性强、大穗玉米良种,采取有效的调控措施是玉米进一步高产的主攻方向。 5)我国夏玉米高产田的培创理论研究与实践相结合,2005 年在我国华北地区的山东莱州培创出籽粒实产21 042.9kg/hm2 ( 14% 含水量, 实收面积=45.7m×15.9m=726.63m2)的夏玉米高产纪录。主要采用以增加密度为保障的“群体结构性挖潜”和以提高整齐度为保障的“个体功能性挖潜”途径,生理生态指标包括:选用紧凑抗倒耐密植品种DH3719,种植密度102 030 株/hm2,收获密度98 610 株/hm2,花后具有较长的叶面积高值持续期,达60d以上,叶面积指数最大为6.53,收获2.59。上部叶片光合值对外界光强度变化敏感,其光合峰值出现时间提前,而后迅速衰减;中部叶片光合值的降低较慢,下部叶片变幅最小,可能是长期处于争光环境表现出的生态适应性。粒叶比0.32,经济系数0.542,单株产量216g,千粒重375.1g。
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The paper deals with the investigations carried out on the preparation of odorless fish-starch flakes using partially deodorized trash fish meat and different sources of starch like corn, tapioca, maida and black gram. It has been found that the products using corn and tapioca are better compared to those prepared using other two starches, the product from corn being the best. The product has a protein content of about 20% and has been found to have a storage life of 4 months at 37°c.
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In the present study, fish cutlets were prepared from bleached and unbleached mackerel mincemeat. Fish cutlets prepared from bleached meat had scored higher values for taste, flavour and overall acceptability as compared to those from unbleached mincemeat. Fish cutlets prepared with corn flour at the rate of 15% of fish mincemeat had scored higher values for all attributes as compared to other levels. Between the bleached and unbleached mincemeat, the scores for cutlet prepared with bleached mincemeat had higher score than that for the latter. There were no cracks in cutlets prepared with 15% and above corn flour levels as compared to those with lower levels. Fish cutlets prepared from bleached and unbleached mincemeat with spice mixture at 20 and 30% of the fish mince, respectively, had higher scores for taste, flavour, texture and overall acceptability as compared to those with other levels. Organoleptic quality of cutlet prepared from bleached and unbleached mackerel mince did not show changes in the appearance, colour and texture during storage. Changes were more prominent in flavour, taste and overall acceptability. Fish cutlets prepared from bleached mincemeat were acceptable for two months and those from unbleached mincemeat were acceptable up to one month from the point of view of organoleptic and biochemical qualities.
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A value-added extruded fish product was prepared with corn flour (80%) and fish (sciaenid) powder (20%), using a twin-screw extruder. The effect of different parameters like moisture, temperature, fish powder concentration, speed of the extruder and die-diameter on expansion ratio and crisp texture were studied. The storage characteristics of the final product were studied using three different types of packaging under nitrogen flushing. The study revealed that aluminum foil is the best packaging material to keep the product acceptable for more than three months.
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The European Control Conferences (ECC) are held every two years, under the auspices of the European Union Control Association (EUCA). The conference is held at the Faculty of Law on the campus of Cambridge University with the exception of the opening planery talks, which is held at the Corn Exchange in the City Center. The scientific program for the ECC03 included 606 regular papers, three plenary talks, six semiplenary talks, three minicourses, and two roundtable sessions.
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The culture of Penaeus monodon has explicitly defined the need for diet formulations or supplementary feeds that would promote optimum growth and survival of the animal. A total of 28 feed combinations were developed for P. monodon. Fish meal, shrimp head meal, squid head meal, Ascetes spp. rice bran, and soybean cake were used as primary ingredients in these feeds. The commercial vitamin mix No. 22 was added to the dry ingredients. Gelatinized corn starch and wheat flour were used as binders. The pellets were extruded using a portable kitchen grinder with a diameter of 4 mm. The products were either sun-dried for 8 hours or oven-dried overnight at 50 degree C to stabilize moisture at 8-10%. The pellets were then kept in covered glass bottles and stored in the laboratory at room temperature. The cost of the feeds excluding labour were also computed. The pellets were analyzed for protein, fat, carbohydrate, crude fiber, ash, and moisture contents using standard procedures. They were also analyzed for water stability. To test the stability of pellets in water, 2-g samples were placed in plankton nets (mesh #40) and suspended in water for two, and six hours. The undissolved samples were then vacuum-dried and the moisture determined. Cost of the feeds ranged from P1.10 to P2.60 per kg depending on the feed ingredient. Squid and Ascetes spp. were rather expensive for use as basic ingredients. Proximate analysis of dry weight showed percentage protein content ranged from 20-63 g; fat, 8-20 g; carbohydrate (by difference), 11-36 g; ash, 8-28 g; moisture, 6-11 g; and crude fiber, 5 . 13 g. Stability tests showed that after two hours, 35-88% of solids remained intact and after 6 hours, 20-55% of the pellets remained undissolved. When a pellet disintegrates easily, pollution of the water occurs. Chances for the shrimp to feed on the pellet is minimized when the pellet is unstable. Thus, the search for a more compact feed pellet has to be continued.
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Corn starch, gelatin, sago palm starch, agar, and bread flour were tested for their binding capacity in pelleted diets for Penaeus monodon . Agar was found to be good binder, but it costs too much, while bread flour was also good but as it's commonly used for human comsumption its use for animal feed should be minimized. The use of 20% bread flour, or a combination of 5% sago palm starch or corn starch with 15% bread flour is recommended, depending on the cost and availability. Basic composition of the formulated diet is tabulated, as is water stability of 2 and 4 mm diameter steamed pellets after 2, 6 and 18 h.
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Penaeus monodon juveniles were reared on semipurified diets containing various carbohydrates (maltose, sucrose, dextrin, molasses, cassava starch, corn starch or sago palm starch). Significant differences were observed between the type as well as the level of carbohydrate in the diet on the survival of the juveniles. Results indicate that there does not seem to be any correlation between survival and the complexity of the carbohydrates.
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State and regional policies, such as low carbon fuel standards (LCFSs), increasingly mandate that transportation fuels be examined according to their greenhouse gas (GHG) emissions. We investigate whether such policies benefit from determining fuel carbon intensities (FCIs) locally to account for variations in fuel production and to stimulate improvements in FCI. In this study, we examine the FCI of transportation fuels on a lifecycle basis within a specific state, Minnesota, and compare the results to FCIs using national averages. Using data compiled from 18 refineries over an 11-year period, we find that ethanol production is highly variable, resulting in a 42% difference between carbon intensities. Historical data suggests that lower FCIs are possible through incremental improvements in refining efficiency and the use of biomass for processing heat. Stochastic modeling of the corn ethanol FCI shows that gains in certainty due to knowledge of specific refinery inputs are overwhelmed by uncertainty in parameters external to the refiner, including impacts of fertilization and land use change. The LCA results are incorporated into multiple policy scenarios to demonstrate the effect of policy configurations on the use of alternative fuels. These results provide a contrast between volumetric mandates and LCFSs. © 2011 Elsevier Ltd.
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The present study aimed to evaluate the effect of dietary linolenic acid (LNA)linoleic acid (LA) ratio on growth performance, hepatic fatty acid profile and intermediary metabolism of juvenile yellow catfish Pelteobagrus fulvidraco. Six isonitrogenous and isolipidic diets were formulated to contain incremental levels of LNA from 0 to 5% at the expense of corn oil (rich in LA), resulting in six dietary treatments with LNA to LA ratios ranging from 0.35 to 14.64. The experiment continued for 7 weeks. Best growth and feed intake were obtained in the fish fed the diets containing the LNA/LA ratios of 1.17 and 2.12 (P<0.05). In contrast, feed conversion ratio was the lowest for fish fed the diets containing the LNA/LA ratios of 1.17 and 2.12 (P<0.05). Dietary LNA to LA ratios significantly influenced viscerosomatic index and hepatosomatic index (P<0.05), but not condition factor (P>0.05). Body composition was also significantly influenced by dietary LNA to LA ratios (P<0.05). Generally, liver FA compositions reflected dietary FA profiles. Declining LA and increasing LNA contents in liver were observed with the increasing dietary LNA/LA ratios (P<0.05). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increased with the increasing LNA to LA ratios, suggesting that yellow catfish could elongate and desaturate C18 polyunsaturated fatty acids into highly unsaturated fatty acids. As a consequence, the n-6 fatty acids (FA) declined, and total n-3 FA and n-3/n-6 ratios increased with the dietary ratios of LNA/LA (P<0.05). Dietary LNA to LA ratios significantly influenced several enzymatic activities involved in liver intermediary metabolism (P<0.05), such as lipoprotein lipase, hepatic lipase, pyruvate kinase, succinate dehydrogenase, malic dehydrogenase and lactate dehydrogenase, suggesting that dietary LNA/LA ratios had significant effects on nutrient metabolism in the liver. To our knowledge this is the first demonstration of the effects of dietary LNA to LA ratios on the enzymatic activities of liver in fish, which provides information on diet quality and utilization, and can also be used as an indicator of the nutritional status of this fish. (C) 2009 Elsevier B.V. All rights reserved.
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An 8-week growth trial was carried out in a semi-recirculation system to investigate the effect of high dietary starch levels on the growth performance, blood chemistry, starch utilization and body composition of gibel carp (Carassius auratus var. gibelio). Five isonitrogenous and isocarloric experimental diets were formulated to contain different starch levels (24%, 28%, 32%, 36% and 40% respectively). Triplicate groups of fish (24 fish per tank with an average body weight, of 8.5 g) were assigned to each diet. The results showed that dietary carbohydrate levels significantly affected the growth performance, hepatopancreatic lipid content, pyruvate kinase (PK) activity and whole-body lipid content. Growth performance, body crude lipid and plasma glucose concentrations showed a decreasing trend with an increase in dietary starch from 24% to 40%. Pyruvate kinase activities and hepatopancreatic lipid content showed an increasing trend with the dietary starch increasing from 24% to 32%, and then a decreasing trend with the dietary starch increasing from 32% to 40%. No significant difference in the hepatopancreatic hexokinase (HK) activity, plasma triglyceride contents, body crude protein, ash and calcium (Ca) and phosphorus (P) contents was observed between different treatments. In conclusion, higher dietary starch levels (32-40%) significantly (P < 0.05) decreased the growth of gibel carp in the present study.
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We investigated the synthesis of dimethyl ether (DME) from biomass synthesis gas using a kind of hybrid catalyst consisting of methanol and HZSM-5 zeolite in a fixed-bed reactor in a 100 ton/year pilot plant. The biomass synthesis gas was produced by oxygen-rich gasification of corn core in a two-stage fixed bed. The results showed that CO conversions reached 82.00% and 73.55%, the selectivities for DME were 73.95% and 69.73%, and the space-time yields were 124.28 kg m- 3 h- 1 and 203.80 kg m- 3 h- 1 when gas hourly space velocities were 650 h- 1 and 1200 h- 1, respectively. Deoxidation and tar removal from biomass synthesis gas was critical to the stable operation of the DME synthesis system. Using single-pass synthesis, the H2/CO ratio improved from 0.98-1.17 to 2.12-2.22. The yield of DME would be increased greatly if the exhaust was reused after removal of the CO2.
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为了探明多年免耕下农田恶性杂草发生的机理,提高保护性耕作下作物对农田恶性杂草持久稳定的抑制效果,依据陕西安塞田间4a的定位试验,采用小区调查取样和室内实验相结合的方法,从物种组成、密度特征、多样性以及相似性特征等方面,研究了黄土丘陵旱作农区大豆(Glycine max)、玉米(Zea mays)、红小豆(Semen Phaseoli)、马铃薯(Solanum tuberosum)在翻耕化肥(CF)、翻耕有机肥(CM)、翻耕无肥(CN)、免耕化肥(NF)、免耕有机肥(NM)、免耕无肥(NN)等水平下的农田土壤种子库。结果表明:(1)4种作物24种土样中共萌发出12个物种1965株幼苗,隶属于7科12属。1年生杂草占94%,棒头草(fugax nees ex steud)、苋菜(Acalypha australis)、马唐(Digitaria sanguinalis)、早熟禾(Poasphondylodes)为优势种,占87%。(2)在0~20cm土层不同处理间,土壤种子库的密度变动于(282.9±63.4)~(7482.5±1078.3)粒.m-2,其中,红小豆小区>马铃薯小区>大豆小区>玉米小区;翻耕小区>免...