Water,land, and energy use efficiencies and financial evaluation of air conditioner cooled greenhouses based on field experiments

High temperature and humidity can be controlled in greenhouses by using mechanical refrigeration cooling system such as air conditioner(AC)in warm and humid regions.This study aims to evaluate the techno-financial aspects of the AC-cooled greenhouse as compared to the evaporative cooled(EV-cooled)greenhouse in winter and summer seasons.Two quonset single-span prototype greenhouses were built in the Agriculture Experiment Station of Sultan Qaboos University,Oman,with dimensions of 6.0 m long and 3.0 m wide.The AC-cooled greenhouse was covered by a rockwool insulated polyethylene plastic sheet and light emitting diodes(LED)lights were used as a source of light,while the EV-cooled greenhouse was covered by a transparent polyethylene sheet and sunlight was used as light source.Three cultivars of high-value lettuce were grown for experimentation.To evaluate the technical efficiency of greenhouse performance,we conducted measures on land use efficiency(LUE),water use efficiency(WUE),gross water use efficiency(GWUE)and energy use efficiency(EUE).Financial analysis was conducted to compare the profitability of both greenhouses.The results showed that the LUE in winter were 10.10 and 14.50 kg/m² for the AC-and EV-cooled greenhouses,respectively.However,the values reduced near to 6.80 kg/m² in both greenhouses in summer.The WUE of the AC-cooled greenhouse was higher than that of the EV-cooled greenhouse by 3.8%in winter and 26.8%in summer.The GWUE was used to measure the total yield to the total greenhouse water consumption including irrigation and cooling water;it was higher in the AC-cooled greenhouse than in the EV-cooled greenhouse in both summer and winter seasons by almost 98.0%–99.4%.The EUE in the EV-cooled greenhouse was higher in both seasons.Financial analysis showed that in winter,gross return,net return and benefit-to-cost ratio were better in the EVcooled greenhouse,while in summer,those were higher in the AC-cooled greenhouse.The values of internal rate of return in the AC-and EV-cooled greenhouses were 63.4%and 129.3%,respectively.In both greenhouses,lettuce investment was highly sensitive to changes in price,yield and energy cost.The financial performance of the AC-cooled greenhouse in summer was better than that of the EV-cooled greenhouse and the pattern was opposite in winter.Finally,more studies on the optimum LED light intensity for any particular crop have to be conducted over different growing seasons in order to enhance the yield quantity and quality of crop.     

水稻僵苗的原因及防治对策

水稻秧苗僵苗的症状表现是植株矮小,叶片细瘦,直立不披散,稻丛呈簇立状,根细而稀,新根少。根据秧苗初期因僵苗程度不同,长相长势有所区别,大致可分3个阶段：发僵,为黄化阶段,叶色较淡,矮小萎黄,锈根多,白根少,呈现出营养不良的症状;以后随着生理缺磷程度的加重,进入蓝化阶段，叶色暗绿发蓝，有的黄中带红，叶片沿纵脉呈环状卷曲，老根直伸向下，根毛稀少，这是由于生理缺磷影响能量代谢，使光合作用产物的运输受到严重阻碍导致的；僵苗严重时为红化阶段，老叶变红色，其余叶片除最新抽出叶呈全绿色外，均有不同程度的叶尖枯焦，远看苗色发红。     

Long-term variations in runoff of the Syr Darya River Basin under climate change and human activities

In this study,we analyzed the hydrological and meteorological data from the Syr Darya River Basin during the period of 1930–2015 to investigate variations in river runoff and the impacts of climate change and human activities on river runoff.The Syr Darya River,which is supplied by snow and glacier meltwater upstream,is an important freshwater source for Central Asia,as nearly half of the population is concentrated in this area.River runoff in this arid region is sensitive to climate change and human activities.Therefore,estimation of the climatic and hydrological changes and the quantification of the impacts of climate change and human activities on river runoff are of great concern and important for regional water resources management.The long-term trends of hydrological time series from the selected 11 hydrological stations in the Syr Darya River Basin were examined by non-parametric methods,including the Pettitt change point test and Mann-Kendall trend tests.It was found that 8 out of 11 hydrological stations showed significant downward trends in river runof f.Change of river runoff variations occurred in the year around 1960.Moreover,during the study period(1930–2015),annual mean temperature,annual precipitation,and annual potential evapotranspiration in the river basin increased substantially.We employed hydrological sensitivity method to evaluate the impacts of climate change and human activities on river runoff based on precipitation and potential evapotranspiration.It was estimated that human activities accounted for over 82.6%–98.7%of the reduction in river runoff,mainly owing to water withdrawal for irrigation purpose.The observed variations in river runoff can subsequently lead to adverse ecological consequences from an ecological and regional water resources management perspective.     

实施植物检疫行政许可中的问题及改进建议

国内农业植物检疫（以下简称植物检疫）是以法律法规为依据、检疫技术为后盾、植物检疫行政许可和执法监督为保障来控制农业有害生物传播、蔓延、危害,达到促进农产品流通,保护农业生态,确保农业生产高产、优质、高效的目的。植物检疫行政许可在植物检疫工作中起着关键的作用。现把江山市2005年以来贯彻实施《行政许可法》和农业部有关农业行政许可规定过程中的有关情况概述如下。     

Identifying water vapor sources of precipitation in forest and grassland in the north slope of the Tianshan Mountains,Central Asia

Identifying water vapor sources in the natural vegetation of the Tianshan Mountains is of significant importance for obtaining greater knowledge about the water cycle,forecasting water resource changes,and dealing with the adverse effects of climate change.In this study,we identified water vapor sources of precipitation and evaluated their effects on precipitation stable isotopes in the north slope of the Tianshan Mountains,China.By utilizing the temporal and spatial distributions of precipitation stable isotopes in the forest and grassland regions,Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model,and isotope mass balance model,we obtained the following results.(1)The Eurasia,Black Sea,and Caspian Sea are the major sources of water vapor.(2)The contribution of surface evaporation to precipitation in forests is lower than that in the grasslands(except in spring),while the contribution of plant transpiration to precipitation in forests(5.35%)is higher than that in grasslands(3.79%)in summer.(3)The underlying surface and temperature are the main factors that affect the contribution of recycled water vapor to precipitation;meanwhile,the effects of water vapor sources of precipitation on precipitation stable isotopes are counteracted by other environmental factors.Overall,this work will prove beneficial in quantifying the effect of climate change on local water cycles.     

加拿大一枝黄花不同成熟度种子的发芽率

在加拿大一枝黄花盛花期,采用剪除花穗、剪除花穗并短截、砍伐植株,以后再采收加拿大一枝黄花种子,于次年进行种子发芽试验.结果表明,3种处理的加拿大一枝黄花种子发芽率均在0.2%～0.4%之间,与对照有极显著差异.     

Coupling analysis of social-economic water consumption and its effects on the arid environments in Xinjiang of China based on the water and ecological footprints

In arid areas,ecological degradation aroused by over-exploitation of fresh water,expansion of artificial oasis and shrinkage of natural oasis,has drawn attention of many scholars and officials.The water and ecological footprints can be used to quantitatively evaluate the water consumption of social-economic activities and their influence on the eco-environments.In addition,increase of the water footprint indicates the expansion of artificial oasis,and the influence on the natural oasis could be reflected by the variation of the ecological footprint.This study was conducted to answer a scientific question that what is the quantitative relationship between the expansion of the artificial oasis and the degradation of the natural oasis in the arid environments of Xinjiang,China.Thus,based on the social-economic data,water consumption data and meteorological data during 2001–2015,we calculated the water and ecological footprints to express the human-related pressure exerted on the water resources and arid environments in Xinjiang(including 14 prefectures and cities),and explore the relationship between the water and ecological footprints and its mechanism by using the coupling analysis and Granger causality test.The results show that both the water and ecological footprints of Xinjiang increased significantly during 2001–2015,and the increasing rate of the ecological footprint was much faster than that of the water footprint.The coupling degree between the water and ecological footprints was relatively high at the temporal scale and varied at the spatial scale.Among the 14 prefectures and cities examined in Xinjiang,the greater social-economic development(such as in Karamay and Urumqi)was associated with the lower coupling degree between the two footprints.Increases in the water footprint will cause the ecological footprint to increase,such that a 1-unit increase in the consumption of water resources would lead to 2–3 units of ecological degradation.The quantitative relationship between the increases of the water and ecological footprints,together with the intensities of water consumption both in the natural and artificial oases of Tarim River Basin,have approved the fact that the formation and expansion of 1 unit of the artificial oasis would bring about the degradation of 2 units of the natural oasis.These conclusions not only provide a technical basis for sustainable development in Xinjiang,but also offer a theoretical guide and scientific information that could be used in similar arid areas around the world.     

Modeling and analyzing supply-demand relationships of water resources in Xinjiang from a perspective of ecosystem services

Water shortage is one bottleneck that limits economic and social developments in arid and semi-arid areas.As the impacts of climate change and human disturbance intensify across time,uncertainties in both water resource supplies and demands increase in arid and semi-arid areas.Taking a typical arid region in China,Xinjiang Uygur Autonomous Region,as an example,water yield depth(WYD)and water utilization depth(WUD)from 2002 to 2018 were simulated using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model and socioeconomic data.The supply-demand relationships of water resources were analyzed using the ecosystem service indices including water supply-demand difference(WSDD)and water supply rate(WSR).The internal factors in changes of WYD and WUD were explored using the controlled variable method.The results show that the supplydemand relationships of water resources in Xinjiang were in a slight deficit,but the deficit was alleviated due to increased precipitation and decreased WUD of irrigation.WYD generally experienced an increasing trend,and significant increase mainly occurred in the oasis areas surrounding both the Junggar Basin and Tarim Basin.WUD had a downward trend with a decline of 20.70%,especially in oasis areas.Water resources in most areas of Xinjiang were fully utilized and the utilization efficiency of water resources increased.The water yield module in the InVEST model was calibrated and validated using gauging station data in Xinjiang,and the result shows that the use of satellite-based water storage data helped to decrease the bias error of the InVEST model by 0.69×10⁸m³.This study analyzed water resource supplies and demands from a perspective of ecosystem services,which expanded the scope of the application of ecosystem services and increased the research perspective of water resource evaluation.The results could provide guidance for water resource management such as spatial allocation and structural optimization of water resources in arid and semi-arid areas.     

How precipitation and grazing influence the ecological functions of drought-prone grasslands on the northern slopes of the Tianshan Mountains,China?

Drought-prone grasslands provide a critical resource for the millions of people who are dependent on livestock for food security.However,this ecosystem is potentially vulnerable to climate change(e.g.,precipitation)and human activity(e.g.,grazing).Despite this,the influences of precipitation and grazing on ecological functions of drought-prone grasslands in the Tianshan Mountains remain relatively unexplored.Therefore,we conducted a systematic field investigation and a clipping experiment(simulating different intensities of grazing)in a drought-prone grassland on the northern slopes of the Tianshan Mountains in China to examine the influences of precipitation and grazing on aboveground biomass(AGB),soil volumetric water content(SVWC),and precipitation use efficiency(PUE)during the period of 2014–2017.We obtained the meteorological and SVWC data using an HL20 Bowen ratio system and a PR2 soil profile hydrometer,respectively.We found that AGB was clearly affected by both the amount and seasonal pattern of precipitation,and that PUE may be relatively low in years with either low or excessive precipitation.The PUE values were generally higher in the rapid growing season(April–July)than in the entire growing season(April–October).Overall,moderate grazing can promote plant growth under water stress conditions.The SVWC value was higher in the clipped plots than in the unclipped plots in the rapid growing season(April–July),but it was lower in the clipped plots than in the unclipped plots in the slow growing season(August–October).Our findings can enhance the understanding of the ecological effects of precipitation and grazing in drought-prone grasslands and provide data that will support the effective local grassland management.     

Effect of the W-beam central guardrails on wind-blown sand deposition on desert expressways in sandy regions

Many desert expressways are affected by the deposition of the wind-blown sand,which might block the movement of vehicles or cause accidents.W-beam central guardrails,which are used to improve the safety of desert expressways,are thought to influence the deposition of the wind-blown sand,but this has yet not to be studied adequately.To address this issue,we conducted a wind tunnel test to simulate and explore how the W-beam central guardrails affect the airflow,the wind-blown sand flux and the deposition of the wind-blown sand on desert expressways in sandy regions.The subgrade model is 3.5 cm high and 80.0 cm wide,with a bank slope ratio of 1:3.The W-beam central guardrails model is 3.7 cm high,which included a 1.4-cm-high W-beam and a 2.3-cm-high stand column.The wind velocity was measured by using pitot-static tubes placed at nine different heights(1,2,3,5,7,10,15,30 and 50 cm)above the floor of the chamber.The vertical distribution of the wind-blown sand flux in the wind tunnel was measured by using the sand sampler,which was sectioned into 20 intervals.In addition,we measured the wind-blown sand flux in the field at K50 of the Bachu-Shache desert expressway in the Taklimakan Desert on 11 May 2016,by using a customized 78-cm-high gradient sand sampler for the sand flux structure test.Obstruction by the subgrade leads to the formation of two weak wind zones located at the foot of the windward slope and at the leeward slope of the subgrade,and the wind velocity on the leeward side weakens significantly.The W-beam central guardrails decrease the leeward wind velocity,whereas the velocity increases through the bottom gaps and over the top of the W-beam central guardrails.The vertical distribution of the wind-blown sand flux measured by wind tunnel follows neither a power-law nor an exponential function when affected by either the subgrade or the W-beam central guardrails.At 0.0H and 0.5H(where H=3.5 cm,which is the height of the subgrade),the sand transport is less at the 3 cm height from the subgrade surface than at the 1 and 5 cm heights as a result of obstruction by the W-beam central guardrails,and the maximum sand transportation occurs at the 5 cm height affected by the subgrade surface.The average saltation height in the presence of the W-beam central guardrails is greater than the subgrade height.The field test shows that the sand deposits on the overtaking lane leeward of the W-beam central guardrails and that the thickness of the deposited sand is determined by the difference in the sand mass transported between the inlet and outlet points,which is consistent with the position of the minimum wind velocity in the wind tunnel test.The results of this study could help us to understand the hazards of the wind-blown sand onto subgrade with the W-beam central guardrails.     

Geochemical weathering of aeolian sand and its palaeoclimatic implications in the Mu Us Desert,northern China,since the Late Holocene

In the semi-arid and arid regions of northern China,geochemical behavior of the aeolian deposit is closely related to climatic and environmental changes,which was used to reconstruct the past history of environmental evolution and possibly forcing mechanisms.However,the related result was still scarce due to the lack of detailed geochemical analysis results in the desert sediments.In the present study,we systematically analyzed the geochemical components and parameters of the paleo-aeolian sand dune and modern mobile sand deposits in the Mu Us Desert and discuss the climatic variation inferred from the paleo-aeolian sand dune during the past 4.2 ka BP.The results indicated that (1) geochemical composition of the sandy deposits were dominated by SiO_2,Al_2O_3 and Na_2O and the deposits probably originated from the widespread upper continental crust (UCC) and were formed by long-term weathering,transport and re-deposition;(2) these sandy deposits were subjected to weaker weathering or uneven weathering under cold and dry conditions,and had highly similar material sources and degrees of weathering and leaching in general;and (3) the direct OSL (Optically Stimulated Luminescence) dating ages and geochemical parameters from the palaeosol-aeolian sand dune indicated that the regional climate change experienced several typically cold and warm intervals.These intervals are 4.2,2.8 ka BP and Little Ice Age and Medieval Warm Period,which probably attributed to periodic variations of the Asian summer monsoonal strength and cold events of the northern Atlantic Ocean in low and high latitudes of the Northern Hemisphere.Our results suggest that the development of the sand dune in the Mu Us Desert provided a suitable archive for understanding the past local climatic change,which is linked to the global climatic change.     

天山中部白杨沟天然林区森林小气候观测与分析

运用自动气象站对天山中部白杨沟天然林区森林内外气象因子进行同步观测,分析晴-多云、阴雨天森林的气温、相对湿度、土壤温度日变化和季节变化特征.结果表明:各季节林冠层平均最高温度和平均最低温度林内均低于林外,平均最高温度林内比林外低2.04℃,平均最低温度林外比林内高1.95℃.冠层相对湿度的平均值较林外高出3.63%,4...     

河北省环境旱化的气候分析

河北省历史上有“十年九旱”之称 ,干旱对农业生产影响很大。其气候原因一是降水少且时空分布不均 ;二是气温偏高 ,蒸发剧烈。利用承德围场站 195 1- 1999年降水量、平均气温和蒸发量的实测资料 ,对年降水量随时间变化进行分析 ,得到年际演变规律。在此基础上进一步分析了降水、气温和蒸发量异常的时空变化特征与河北省环境旱化之间的关系。在初步分析全省环境旱化成因后 ,提出若干治理干旱的对策措施———建立健全干旱监测预警措施、加快水利建设、充分利用空间水资源、推广旱作节水农业技术、开展高效特色农业开发。     

Two-way coupling of unsaturated-saturated flow by integrating the SWAT and MODFLOW models with application in an irrigation district in arid region of West China

This paper presents the realization of two-way coupling of the unsaturated-saturated flow interactions of the SWAT2000 and MODFLOW96 models on the basis of the integrated surface/groundwater model SWATMOD99, and its application in Hetao Irrigation District (HID), Inner Mongolia, China. Major revisions and enhancements were made to the SWAT2000 and MODFLOW models for simulating the detailed hydrologic budget and coupled unsaturated and saturated interactions, and irrigation canal hydrology for the HID. The simulation results of seasonal groundwater recharge to and evaporate from the shallow groundwater, and the annual water budget over the district are presented and discussed. The results implied the necessity of two-way coupling of the unsaturated-saturated interactions when groundwater is shallow, and the feasibility of making comprehensive use of the information coming from both the surface water and groundwater models to make a more physically-based assessment of the coupled interactions.     

药液表面张力和黏度对草甘膦药效的影响及其机理研究

通过添加有机硅助剂和丙三醇调节草甘膦药液的表面张力和黏度,测定其对草甘膦药液液滴的物理性状及生物活性的影响。结果表明：降低药液的表面张力,雾滴的铺展直径增加,干燥时间缩短,药液的黏度以及在杂草叶片表面的最大稳定持留量没有显著性变化;草甘膦对杂草的防效表现为先升高后降低,对阔叶杂草最高目测防效和鲜重防效可提高42%和41%,对禾本科杂草防效可提高37%和37%。增加草甘膦的药液黏度,药液在杂草叶片上的最大稳定持留量增加,表面张力降低,对雾滴的干燥时间和铺展直径影响很小;草甘膦对阔叶杂草最高目测防效和鲜重防效可提高42%和41%,对禾本科杂草的防效可提高42%和42%。适当降低草甘膦药液的表面张力或增加其黏度均可提高其对杂草的防除效果。     

增效剂对桔小实蝇抗药性的影响

采用药膜法分别测定了增效醚(PBO)和磷酸三苯酯(TPP)两种增效剂对桔小实蝇抗敌百虫、高效氯氰菊酯和阿维菌素三个种群的抗药性产生的影响。结果表明,对这三种药剂分别产生的桔小实蝇抗性种群,PBO和TPP均能对其抗药性有一定的影响,但影响程度不同,对抗敌百虫、抗高效氯氰菊酯的两个桔小实蝇种群,TPP对敌百虫和高效氯氰菊酯的增效作用均高于PBO,且增效作用显著,增效比分别达3.98和2.43,PBO的增效比为1.71和1.66;对抗阿维菌素的桔小实蝇种群则略相反,PBO对阿维菌素的增效作用高于TPP,但增效作用均低于敌百虫与高效氯氰菊酯。     

全球变暖背景下天山地区近地面水汽变化研究

利用天山地区44个站1961-2009年水汽压数据,采用线性趋势估计、距平分析、Mann-Kendall趋势统计突变检验和功率谱等方法,分析天山地区近地面水汽变化及其与区域气候变化的关系。结果表明：天山地区近49 a来水汽总体呈增多趋势,年和四季水汽变化具有年际和年代际差异,最大增多趋势均出现在20世纪90年代中后期至21世纪初,最小值出现在70年代中后期和80年代中期,最大值出现在21世纪初。突变和周期分析得出,水汽年变化与西北地区气候变化趋势具有明显一致性。年降水变化与水汽相关最高,温度和青藏高原指数次之,其他因子相关一般。     

宁夏草原蝗虫多样性及其对环境因子的响应

为明确宁夏四类主要草原的蝗虫物种组成、多样性和对天敌、植被、土壤及其气候等生物和非生物因子的响应,2019-2020年在宁夏温性草甸草原、温性草原、温性荒漠草原和温性草原化荒漠四类草原对蝗虫及天敌物种进行了调查采集,通过物种数、个体数、多样性指数、优势度指数、丰富度指数及均匀性指数分析蝗虫、天敌和昆虫的多样性,并就草原蝗虫优势种和多样性对天敌、植被、土壤及气候等生物和非生物因子的响应进行分析。结果表明,共采集鉴定草原蝗虫和天敌个体数分别有743头和3592头,物种数分别有27种和24种;温性草原上发生的蝗虫和天敌物种和数量均最多,蝗虫和天敌的物种分别为23种和21种,数量分别为432头和1682头;温性草原化荒漠上发生的蝗虫和天敌物种和数量均最少,蝗虫和天敌的物种分别为8种和7种,数量分别为34头和132头。蝗虫优势种有白纹雏蝗Chorthippus albonemus、短星翅蝗Calliptamus abbreviatus和亚洲小车蝗Oedaleus asiaticus三种,天敌优势种有直角通缘步甲Pterostichus gebleri、麻步甲Carabus brandti和短翅伪葬步甲Pseudotaphoxenus brevipennis三种。温性草原无论是在草原蝗虫群落中,还是整个昆虫和天敌群落中,其丰富度指数均显著高于其他三类草原;草原蝗虫多样性指数和丰富度指数与天敌多样性指数和丰富度指数间均存在极显著正相关关系,与天敌优势度指数间存在极显著负相关关系;短星翅蝗和亚洲小车蝗发生均与天敌直角通缘步甲呈显著正相关关系,白纹雏蝗与禾本科植被盖度、高度、生物量,菊科植被盖度、生物量、频度、高度、土壤饱和持水量、毛管持水量、田间持水量、毛管孔隙度、总孔隙度、有机质、碱解氮、海拔和降水量间均呈显著正相关关系,与土壤容重、pH、平均气温和最高气温间均呈极显著负相关关系。     

新疆夏尔希里自然保护区植物区系研究

经调查,夏尔希里自然保护区共有维管束植物81科517属1 680种(含亚种、变种),其中蕨类植物9科14属23种,裸子植物3科3属9种,被子植物69科500属1648种.对其属、种的分布区类型分析表明,北温带分布及变型和旧世界温带分布及变型的比例最大,这是由于该地区所处地理位置和植物区系的温带属性所决定的.在其他分布区...     

农林害虫诱捕器应用技术

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