大叶桃花心木花粉精油的杀虫及抑菌活性

采用超临界CO2萃取大叶桃花心木(Swietenia macrophylla)花粉精油,并研究其对4种田间害虫的杀虫活性以及8种植物病原真菌的抑菌效果.结果表明,在2 g·L?1浓度下,大叶桃花心木花粉精油对莴苣指管蚜(Uroleucon formosanum)具有很好的触杀活性,对玉米象(Sitophilus zea...     

冠状环柄菇和豹斑毒鹅膏菌的复合毒素粗品对玉米象的毒效

为微生物杀虫剂的开发与利用提供新的理论依据,利用冠状环柄菇和豹斑毒鹅膏菌的毒素粗品复合物,研究其对玉米象的毒杀效果,测定2种毒蕈的毒素粗品及其复合物对玉米象的毒杀效果、致死浓度及致死率。结果表明,冠状环柄菇和豹斑毒鹅膏菌的毒素粗品及其复合物均具有毒杀玉米象的作用,其中,豹斑毒鹅膏菌对玉米象的毒杀效果优于冠状环柄菇。施药24h后,2种毒蕈对玉米象都有显著的毒杀效果;2种毒蕈毒素粗品的复合物短时间内加大用量,对玉米象的杀虫效果更佳。结论:冠状环柄菇与豹斑毒鹅膏菌的复合毒素粗品作为一种复合微生物杀虫剂,对玉米象有较好的防治效果。     

超临界CO2萃取花椒挥发油的杀虫活性研究

应用超临界CO2萃取技术提取得到的花椒挥发油对玉米象、赤拟谷盗进行了杀虫活性测定.结果表明,花椒挥发油对玉米象、赤拟谷盗具有较强的驱虫、杀虫活性.在7 d内忌避率始终在50%以上;在椒油点滴剂量为0.04μL时,玉米象和赤拟谷盗的死亡率分别为47%和40%;当玉米象的熏杀剂量为1 mL·L-1时,24 h内虫全部死亡,当对赤拟谷盗的熏杀剂量为1.2 mL·L-1时,6 h内虫全部死亡.     

生物有机肥对工程扰动土地玉米的光合特性及产量的影响——以乌蒙山区云南省曲靖市马龙县试验地为例

[目的]研究生物有机肥对工程扰动土地玉米的光合特性及产量的影响。[方法]以马龙县工程扰动1年土壤和玉米为研究对象和材料,研究不同施肥处理对工程扰动地玉米光合特性和产量的影响。[结果]与不施肥处理相比,配施生物有机肥处理的玉米光合速率显著提高、胞间CO2浓度均有提高;配施生物有机肥处理除牛粪与菌剂组a处理外,玉米产量明显提高,以牛粪与菌剂b配施化肥的处理效果最显著。与单施化肥相比,配施生物有机肥处理中牛粪与菌剂b处理对玉米光合速率、气孔导度、胞间CO2浓度、蒸腾速率的影响均达最高,产量也达最高;除胞间CO2浓度外,牛粪与菌剂b处理与单施化肥处理相比对玉米光合速率、气孔导度、蒸腾速率的影响均达显著性差异。菌剂b对工程扰动玉米光合速率提升效果、玉米胞间CO2浓度提升均优于菌剂a。腐熟牛粪效果好于精制有机肥。生物有机肥处理中,牛粪对玉米蒸腾速率的影响的效果优于精制有机肥。[结论]该研究为合理施肥、快速培肥工程扰动土壤、提高作物产品质量提供科学依据和实践指导。     

沼气储粮对玉米象害虫控制效果的研究

[目的]探究沼气储粮对储粮害虫玉米象的控制效果。[方法]利用沼气进行粮食储存,研究了在甲烷浓度分别为70%、50%、30%的储存条件下种子中玉米象的出虫率和死亡率,研究了水分含量对种子出虫的影响,并考察了沼气储存对玉米种子发芽的影响。[结果]粮种的出虫率随甲烷浓度的降低而增加,最大差值为5.91%;而储粮害虫的死亡率随甲烷浓度的降低而降低,最大差值达71.81%,即沼气储粮的效果是很明显的,但杀虫效果在一定程度上受到种子水分等因素的影响;在储粮过程中,沼气并不影响种子发芽,更不会改变种子成分而使其发生变质,甚至还有保鲜作用。[结论]为仓储害虫的有效控制提供了理论依据。     

长期CO_2加富对玉米(粤甜1号)光合生理与生长发育的研究

以塑料薄膜温室为设施,研究了玉米粤甜1号叶片光合生理特性对CO2浓度加富的响应。结果表明:处理60d时,玉米处理组T1(600±40)μmol CO2·mol-1的净光合速率分别为对照组[大气CO2浓度,(360±30)μmol CO2·mol-1]的103.79%;而处理组T2(900±40)μmol CO2·mol-1为对照的105.18%;CO2浓度加富处理促进了玉米叶片中可溶性糖和淀粉积累,Rubisco羧化酶活性无显著变化;叶绿素含量下降,CO2浓度加富处理条件下玉米粤甜1号反应不明显。     

石菖蒲根茎提取物β-细辛醚对玉米象成虫的毒力及防治效果

采用药膜法、滤纸药膜法和饲料拌药法分别检测β-细辛醚对玉米象成虫的触杀、驱避及种群抑制等作用.结果表明,β-细辛醚对玉米象成虫具有良好的防治效果.β-细辛醚157.30、78.63 μg/cm2浓度处理玉米象成虫96 h后的校正死亡率分别高达100.00%和93.22%,处理96 h后的触杀毒力LC50为28.22 μg/cm2;157.30、78.63、39.32 μg/cm2浓度处理的β-细辛醚对玉米象成虫的平均驱避率在V级以上,较低浓度19.66 μg/cm2处理的驱避率也达到了Ⅳ级;0.500 g/kg的浓度处理7 d后,玉米象成虫的校正死亡率达到91.11%,处理45 d后,对子代种群抑制率也高达100.00%.     

中药植物丁香杀虫杀螨活性研究

系统研究了中药植物丁香的杀虫和杀螨活性。采用正己烷、苯、乙醚、甲醇和水对丁香进行顺序提取,分别测定提取物对朱砂叶螨和玉米象等供试生物的活性,结果表明：丁香的正己烷提取物24h和72h对朱砂叶螨的致死中浓度(LC50)分别为1．5333和0．5796g／L;苯的提取物24h和72h对朱砂叶螨的致死中浓度(LC50)分别为4.4393和1．3537g／L;丁香的正己烷提取物熏蒸处理7d,对玉米象的校正死亡率达94．44％。     

细辛醚对6种农业害虫的杀虫活性

【目的】进一步确定细辛醚的杀虫作用。【方法】在不同作用方式下测定了细辛醚对粘虫、桃蚜、菜青虫、棉铃虫、玉米象和赤拟谷盗等6种农业害虫的室内毒力。【结果】细辛醚对粘虫、桃蚜和菜青虫24 h的触杀LD50值分别为35.06,1.11,66.28μg/头,在供试剂量下对棉铃虫、玉米象和赤拟谷盗成虫的触杀作用较差;对粘虫和玉米象的熏蒸LC50值分别为16.92(12 h)和7.53(72 h)μL/L;对玉米象有一定的忌避作用,忌避作用随时间延长而减弱;细辛醚质量浓度为1,5和10 mg/g的处理,33 d对玉米象的致死率分别为26.97%,86.51%和100%,1,5 mg/g处理33 d和76 d对玉米象种群抑制率分别为74.18%和96.54%,63.64%和81.28%;经细辛醚处理的粘虫幼虫表现出明显的兴奋、痉挛、麻痹和死亡等症状。【结论】细辛醚对粘虫有较好的熏蒸、触杀作用,对桃蚜、菜青虫具有较强的触杀作用,对玉米象有一定的熏蒸、忌避和种群抑制作用,而对棉铃虫和赤拟谷盗的活性较差,具有明显的杀虫选择性。细辛醚对昆虫的致毒症状与神经毒剂类似。     

紫茎泽兰精油各馏份对4种仓库害虫的杀虫活性

用紫茎泽兰精油的20℃～150℃,150℃～2℃,200℃～230℃,230℃300℃和300℃以上馏份,分别以44.44mg/L的熏蒸浓度处理米象、玉米象、绿豆象和蚕豆象,结果表明,在5个馏份中,以150℃～200℃馏份的杀虫活性最高,其次是20℃～150℃和200℃～230℃馏份,而300℃以上馏份的杀虫活性最低.进一步的生测结果表明,150℃～200℃馏份对米象、玉米象、绿豆象和蚕豆象24h的LC50分别为15.5114,17.8124,18.0302和16.2671mg/L.     

气候变化对中国粮食贸易的影响研究(英文)

[目的]研究气候变化因素对中国粮食贸易的影响。[方法]通过建立粮食贸易引力模型,分析影响中国粮食贸易的因素,如GDP、人口、粮食产量、二氧化碳排放量、气温等。[结果]中国GDP与粮食贸易量负相关,原因与粮食的需求弹性有关;二氧化碳排放量与粮食贸易量正相关。[结论]中国粮食种植品种结构应该随人们食物消费结构的变化而有所调整;在粮食生产和流通环节,应该有更好的制度安排,减少二氧化碳的排量。     

Carbon-negative biofuels from low-input high-diversity grassland biomass

Biofuels derived from low-input high-diversity (LIHD) mixtures of native grassland perennials can provide more usable energy, greater greenhouse gas reductions, and less agrichemical pollution per hectare than can corn grain ethanol or soybean biodiesel. High-diversity grasslands had increasingly higher bioenergy yields that were 238% greater than monoculture yields after a decade. LIHD biofuels are carbon negative because net ecosystem carbon dioxide sequestration (4.4 megagram hectare(-1) year(-1) of carbon dioxide in soil and roots) exceeds fossil carbon dioxide release during biofuel production (0.32 megagram hectare(-1) year(-1)). Moreover, LIHD biofuels can be produced on agriculturally degraded lands and thus need to neither displace food production nor cause loss of biodiversity via habitat destruction.     

A sublimation model for martian south polar ice features

In their pioneering work, Leighton and Murray argued that the Mars atmosphere, which at present is 95% carbon dioxide, is controlled by vapor equilibrium with a much larger polar reservoir of solid carbon dioxide. Here we argue that the polar reservoir is small and cannot function as a long-term buffer to the more massive atmosphere. Our work is based on modeling of the circular depressions commonly found on the south polar cap. We argue that a carbon dioxide ice layer about 8 meters thick is being etched away to reveal water ice underneath. This is consistent with thermal infrared data from the Mars Odyssey mission.     

Europe's terrestrial biosphere absorbs 7 to 12% of European anthropogenic CO2 emissions

Most inverse atmospheric models report considerable uptake of carbon dioxide in Europe's terrestrial biosphere. In contrast, carbon stocks in terrestrial ecosystems increase at a much smaller rate, with carbon gains in forests and grassland soils almost being offset by carbon losses from cropland and peat soils. Accounting for non-carbon dioxide carbon transfers that are not detected by the atmospheric models and for carbon dioxide fluxes bypassing the ecosystem carbon stocks considerably reduces the gap between the small carbon-stock changes and the larger carbon dioxide uptake estimated by atmospheric models. The remaining difference could be because of missing components in the stock-change approach, as well as the large uncertainty in both methods. With the use of the corrected atmosphere- and land-based estimates as a dual constraint, we estimate a net carbon sink between 135 and 205 teragrams per year in Europe's terrestrial biosphere, the equivalent of 7 to 12% of the 1995 anthropogenic carbon emissions.     

Fate of fossil fuel carbon dioxide and the global carbon budget

The fate of fossil fuel carbon dioxide released into the atmosphere depends on the exchange rates of carbon between the atmosphere and three major carbon reservoirs, namely, the oceans, shallow-water sediments, and the terrestrial biosphere. Various assumptions and models used to estimate the global carbon budget for the last 20 years are reviewed and evaluated. Several versions of recent atmosphere-ocean models appear to give reliable and mutually consistent estimates for carbon dioxide uptake by the oceans. On the other hand, there is no compelling evidence which establishes that the terrestrial biomass has decreased at a rate comparable to that of fossil fuel combustion over the last two decades, as has been recently claimed.     

沟播对盐碱地小麦花后光合特性及产量的影响

以青麦6号为材料,设置平播(CK)、沟内2行、沟内3行3种处理,探究了沟播对盐碱地小麦(Triticum aestivum L.)花后光合特性及产量的影响。结果表明,产量与净光合速率、气孔导度、蒸腾速率、叶绿素SPAD值、穗数、千粒重呈极显著(P0.01)正相关,与每穗粒数呈显著(P0.05)正相关,与胞间CO2浓度呈极显著(P0.01)负相关;两种沟播处理较平播显著提高了盐碱地小麦的叶绿素含量、净光合速率、气孔导度和蒸腾速率,并提高了胞间CO2的利用能力。与CK相比,沟播显著(P0.05)提高了小麦产量与穗数,但其每穗粒数和千粒重差异不显著(P0.05),表明沟播主要通过影响小麦的穗数进而影响小麦产量。通过对不同栽培方式下光合特性及产量等因素的分析,确定沟内3行是盐碱地小麦较为合理的栽培措施。     

Climatic change: are we on the brink of a pronounced global warming?

If man-made dust is unimportant as a major cause of climatic change, then a strong case can be made that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide. By analogy with similar events in the past, the natural climatic cooling which, since 1940, has more than compensated for the carbon dioxide effect, will soon bottom out. Once this happens, the exponential rise in the atmospheric carbon dioxide content will tend to become a significant factor and by early in the next century will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years.     

High photosynthetic capacity of a winter annual in death valley

Camissonia claviformis, a winter annual of Death Valley, California, that fixes carbon dioxide by the C(3) mechanism, has an in situ photosynthetic rate at midday in spring of nearly 6 nanomoles of carbon dioxide per square centimeter per second-an exceptionally high rate. Camissonia fixes absorbed noon sunlight in the 400- to 700-nanometer region into chemical energy with an efficiency of 8.5 percent, which is 80 percent of that theoretically possible for intact leaves. This performance is primarily due to an unusual capacity to utilize high irradiances. Factors associated with this include a high stomatal conductance to carbon dioxide and high levels of soluble protein and ribulose-1,5-diphosphate carboxylase.     

Increasing atmospheric carbon dioxide: tree ring evidence for growth enhancement in natural vegetation

A response of plant growth to increased atmospheric carbon dioxide, which has been anticipated from laboratory data, may now have been detected in the annual rings of subalpine conifers growing in the western United States. Experimental evidence shows that carbon dioxide can be an important limiting factor in the growth of plants in this high-altitude environment. The greatly increased tree growth rates observed since the mid-l9th century exceed those expected from climatic trends but are consistent in magnitude with global trends in carbon dioxide, especially in recent decades. If correctly interpreted, these findings have important implications for climate studies involving tree ring observations and for models of the global carbon dioxide budget.     

Gas emissions and the eruptions of mount st. Helens through 1982

The monitoring of gas emissions from Mount St. Helens includes daily airborne measurements of sulfur dioxide in the volcanic plume and monthly sampling of gases from crater fumaroles. The composition of the fumarolic gases has changed slightly since 1980: the water content increased from 90 to 98 percent, and the carbon dioxide concentrations decreased from about 10 to 1 percent. The emission rates of sulfur dioxide and carbon dioxide were at their peak during July and August 1980, decreased rapidly in late 1980, and have remained low and decreased slightly through 1981 and 1982. These patterns suggest steady outgassing of a single batch of magma (with a volume of not less than 0.3 cubic kilometer) to which no significant new magma has been added since mid-1980. The gas data were useful in predicting eruptions in August 1980 and June 1981.