盐碱地杂草的利用

盐碱地是指含盐量较高，天然生长的植物种类较少的土地。盐碱地一般植被都较差，在此类土地上能够生长的植物大多属杂草的范畴。因此，研究盐碱地杂草的利用对于盐碱地开发和利用具有十分重要的意义。     

新疆生物改良盐碱地效益研究

生物改良盐碱地主要是通过将种植业与养殖业有机的结合起来,培肥地力,从而提高盐碱地(盐渍化土地、碱化土地)的经济效益。在土壤盐分含量较高时,通过2a直接种植比较耐盐的禾本科牧草,0～40cm土壤的脱盐率可达67．3％以上;种植直根系作物枸杞3a后,0～40cm土壤的脱盐率为78．7％。而利用灌水洗盐方式改良盐碱地耗水量大,是生物改良方式的1．6倍。在土壤盐分含量高于1．5％时,利用生物方式改良后土地的产量高于灌水洗盐后的产量。生物改良盐碱地是生态、经济和社会效益兼优的改良盐碱地模式。在以硫酸盐为主的干旱区盐碱地,种植耐盐牧草结合正常灌溉改良盐碱地切实可行。     

干旱区盐渍化土地三系统治理技术研究

运用工程改良、生物种植改良、养殖业发展增加土壤有机质的“三系统”治理盐渍化土地技术把“食物链－生产链－产业链”有机地连成一条主线,实现了农林牧互促相长的盐碱地治理利用可持续发展的目的。在干旱区临泽县小泉子盐渍化土地中实施4a来,使土壤含盐量降低40．6％－76．3％,土壤有机质增加29．2％左右,土壤孔隙度提高4．28％,全氮增加11．7％;示范区粮食产量增加了69．13％,示范农户经济收入增加23．37％。     

滨海盐碱地“台田-浅池”改良措施的研究进展

滨海盐碱地是我国一类重要的土地资源,但其特殊的土壤理化性质严重制约植物的生长。长期以来,国内外学者已对我国滨海盐碱土的理化性质和水盐运动进行了深入研究,并据此提出了相应而有效的滨海盐碱土物理、化学、生物方面的改良措施。近年来,“台田-浅池”型综合土地利用模式（挖土成池,筑土为台,台田种植,浅池养殖）是我国一种新型的滨海盐碱地综合改良模式,它集合了国内外优秀的滨海盐碱地改良方法,并创新性的将新型水资源---海冰水应用在滨海盐碱地的改良利用中,目前已经在土地利用变化和优化配置、台田修筑、盐碱地改良、土壤水盐运动、海冰水灌溉、作物种植、耐盐植物筛选、咸淡水混合养殖等多方面进行了综合利用试验,并在降低土壤盐度,增强土壤肥力,提高作物产量,增加经济效益等方面取得了良好的效果。未来,提高土壤肥力、选择适宜作物品种、使用风能太阳能等清洁能源、协调生态发展、实现滨海盐碱地可持续利用是“台田-浅池”综合利用模式研究的新方向。     

半干旱地区土地退化遥感动态监测方法-以吉林省通榆县为例

在RS和GIS集成技术支持下 ,选取位于半干旱地带的土地退化典型地区 -吉林省通榆县 ,利用不同时相的TM卫星数据 ,采用噪声白化变换提取光谱特征 ,选用植被、盐碱地、裸沙地、沼泽土、苇地作为最终光谱单元进行线性混合光谱分解 ,依据盐碱地和裸沙地加权和分量 ,将试点区的土地退化划分为未退化、轻度退化、中度退化和重度退化四个等级进行动态监测 ,并对土地退化的数量、空间分布与动态过程进行了分析。这一研究方法与结果可为半干旱地区的土地退化监测与生态建设提供科学方法和依据。     

松嫩平原典型盐碱化地区土地利用格局变化研究——以吉林省乾安县为例

基于两期土地利用遥感数据,并结合统计与调查资料,本文使用地理信息系统技术和景观生态学方法,对1945~1996年吉林省乾安县的土地利用格局变化进行了研究。结果表明:1)就乾安县的整体土地利用变化而言,主要表现为景观破碎化,斑块不规则化和景观结构复杂化。2)就各土地利用类型的变化而言,突出表现为草地和湿地大幅减少,景观百分比显著下降,同时耕地和盐碱地大幅增加,景观百分比显著上升。3)就各土地利用类型之间的转换而言,主要表现为草地、林地、盐碱地和湿地向耕地的转化,以及耕地、草地、水域和湿地向盐碱地的转化。4)就各土地利用类型结构的变化而言,突出表现为草地和湿地遭受严重分割,出现严重的破碎化;而耕地和盐碱地斑块日益扩大,连通度上升。5)就土地利用格局变化的环境效应而言,草地和湿地的大幅减少以及盐碱地的显著扩展已经对当地的生存环境构成了严重威胁。     

中麻黄的适应性及其抗逆性栽培

中麻黄具有较强的旱生性和耐盐性 ,在逆境盐碱地栽培其经济效益、缓解天然麻黄资源破坏、减缓土地沙化的生态效益比较显著 ,是干旱区盐碱地农村调整种植结构、退耕还林的优良植物种。     

土地整治工程对土壤碳固持的影响

为了探求土地整治工程对土壤碳固持的效应,分析在改善土地利用形式和条件的同时,对生态环境效应的影响等。本研究开展了盐碱地、风沙地和黄土废弃宅基地等3类土地整治工程对土壤碳固持的作用和影响研究。结果表明,盐碱地、风沙地和废弃宅基地等3类土地整治类型土壤剖面总碳含量均得到提高;风沙地、废弃宅基地整治类型,土壤有机碳含量的变化显著影响土壤剖面总碳含量;而盐碱地整治类型,无机碳含量的变化显著影响土壤剖面总碳含量。3类整治类型不同程度地促使0~100 cm土壤剖面碳密度的提升;盐碱地、风沙地整治类型土壤剖面上的总碳含量和总碳密度变化趋势较一致;废弃宅基地整治类型因土壤容重变化较大,土壤剖面上的土壤总碳含量与总碳密度变化趋势不一致。由此可以得出,土地整治对增加农田土壤碳库容量有着重要意义,研究不同类型土地整治对土壤碳固持的影响有助于精确评估土壤碳库的总储量。     

土地利用/覆被变化对区域蒸散发影响的遥感分析——以吉林省乾安县为例

以吉林省西部乾安县为例,基于Landsat TM和ETM+影像,分析该区1989年和2001年2期土地利用/覆被变化对区域蒸散发的影响。结果表明:从1989-2001年,乾安县土地利用/变化显著。草地→耕地、草地与不同程度盐碱地、不同程度盐碱地内部的转换为主要土地利用变化类型。12年来,不同土地利用类型的平均日蒸散量格局基本一致,表现为:水体>湿地/耕地>林地>草地/轻度盐碱地>居民用地>中度盐碱地>重度盐碱地。其中,59.6%的地表蒸散强度变化区的土地利用/覆被发生变化。草地→耕地、草地→不同程度盐碱地、不同程度盐碱地→草地的蒸散强度变化以基本不变、减少、增加为主;由轻度盐碱地向重度盐碱地逐渐转变时,蒸散强度降低,反之增加。由于草地的植被覆盖度减少,其蒸散强度降低,而林地、居民用地、轻度盐碱地的植被覆盖度增加,蒸散强度以增加为主。     

渭河下游洪泛区土地景观格局变化及驱动力研究

应用GIS/RS技术与景观格局分析软件FRAGSTATS,研究了1989-2000年渭河下游洪泛区土地景观格局变化及其驱动力.结果表明:①建设用地、草地、盐碱地、裸地、林地和园地的面积在增加,而耕地和水域的面积在减少;土地盐碱化形势依旧严峻,累计有2.08 km2的耕地和0.94 km2的草地出现了盐碱化,而且由于径流量减少使得3.47 km2的水域暴露并演化为盐碱地.②景观系统中优势斑块类型的连接性逐步降低,景观破碎化程度和景观异质性均呈现出增高趋势,其不定性的信息含量增大;耕地和林地的异质性及破碎度均有所降低,而建设用地则相反;草地、盐碱地和水域的各项指数波动性较大,景观变化较为剧烈.③人口增长、农业生产、区域产业结构调整以及水利工程等因素所引发的河道变迁、洪涝灾害频发等环境问题是促使景观类型转变的重要驱动力.④保护为主、合理开发洪泛区资源,适当退耕、重建河岸植被带等措施应该是洪泛区土地管理的唯一途径.     

Changes in agronomic practices and incidence and severity of diseases in winter wheat in England and Wales between 1999 and 2019

In continuation of the annual national surveys of winter wheat, which began in 1970, samples from between 250 and 350 randomly selected wheat crops in England and Wales between 1999 to 2019 were visually assessed for disease symptoms during the milky ripe development stages (GS 73–75). Septoria tritici blotch was the most prevalent and severe foliar disease each year, although annual levels fluctuated considerably and there was no overall significant change over the two decades. Incidence of brown rust, yellow rust, take-all, and barley yellow dwarf virus also showed no significant overall change during the survey period, whereas glume blotch, powdery mildew, eyespot, and sharp eyespot all showed significant decline. Fusarium ear blight has significantly increased in both incidence and severity, causing a serious epidemic in 2012, when 96% of crops were affected. Tan spot has been the third most prevalent foliar disease since 2009 although severity is still very low. Regional disease levels were consistent over the two decades, providing reliable baselines to measure changes in seasonal disease severity. There were significant changes in agronomic practice with a rise to predominance of minimum tillage over the use of ploughing, decreases in overall disease susceptibility of cultivars grown, a major increase in the use of oilseed rape in the rotation and a long-term trend towards earlier sowing. Fungicide use increased considerably, with over 98% crops sprayed and an average of 3.5 applications made per crop each year since 2014. Implications of changes over the last 21 years are discussed.     

吡虫啉和百菌清在设施内外葫芦和黄瓜中的残留特性比较

采用高效液相色谱和气相色谱法,分别研究了吡虫啉和百菌清在薄膜大棚设施内外葫芦叶和黄瓜中消解动态及其在葫芦和黄瓜中的残留量,并结合气象因子对产生残留差异的原因进行了分析。样品中的吡虫啉经乙腈和盐酸溶液提取,中性氧化铝和弗罗里硅土层析柱净化后,用高效液相色谱检测;百菌清经乙腈提取,中性氧化铝层析柱净化后,用气相色谱检测。结果表明:吡虫啉在设施内外葫芦叶和黄瓜中均消解迅速,施药7 d后,其在设施内外葫芦叶上的消解率分别为90.4%和98.7%,在黄瓜中的消解率分别为67.8%和85.9%;而百菌清在葫芦叶上的消解速率均比在黄瓜中的稍慢,施药7 d后其在设施内外葫芦叶上的消解率分别为15.4%和38.1%,在黄瓜中的消解率分别为87.8%和91.5%。表明2种农药在设施外2种蔬菜上的消解速率均快于设施内的。两种农药均是在设施外葫芦及黄瓜中的残留量低于设施内的,而降雨和光照强度可能是引起农药在设施内外蔬菜上残留差异的主要因子。     

中国的沙暴、尘暴及其防治

沙尘暴在进入 90年代以来有进一步加剧趋势 ,其原因在于此期我国西北地区气候干暖化态势明显 ,人类超负荷开发资源加剧 ,从而导致沙尘暴的频繁发生 ,但总体上仍属于正常的灾害现象。我国沙暴只能发生于干旱半干旱区 ,尘暴则可波及半湿润与湿润区 ,由此而论 ,北京的沙尘暴属于尘暴范畴 ,北京不会形成沙漠区。防治沙尘暴必须采取水、土、植被综合防治措施 ,基本对策是 :1 .搞好流域为单元的水土资源合理利用规划 ,进行水土保持综合防治 ;2 .增加地表植被复盖 ,搞好防护林体系建设 ;3 .减轻土地利用强度 ,恢复提高土地抗蚀能力 ;4.加强管理体系建设 ,依法建设生态环境。建议国家设立水土保持为主要职能的生态环境建设委员会 ,统一协调布署我国的生态环境建设工作。     

Trends and expectations for research and technology in weed science in Thailand

There are many possible ways to improve the economic crisis in Thailand, and it is agreed that development of agricultural production is ideal for improving the economic situation in an agricultural country such as Thailand. A strategic plan for agricultural and agro‐industry research is included in the national research agenda and can be classified into nine groups covering different research areas. Most research is based on the agricultural production of four main product groups: (i) crops; (ii) aquatic animals/plants and fisheries products; (iii) poultry, livestock and animal products; and (iv) forest resources. Trends in research and development in weed management for crop production will continue to support the food demands and the development of efficient production of quality products.     

Variation in seed dormancy and light sensitivity in Alopecurus myosuroides and Apera spica-venti

Variation in seed dormancy and light sensitivity was studied in Alopecurus myosuroides and Apera spica-venti . Seeds were collected from different populations, at different dates and from plants emerging in autumn or spring, and used in four experiments. In the first experiment, initial dormancy was investigated in light and darkness. In Expt 2, buried seeds were exhumed on 16 occasions, from September 1997 to March 2000, and germinated in light, in darkness and after a 5-s light exposure. In Expt 3, emergence was recorded for seeds sown in pots outdoors. In Expt 4, stratified seeds of A. myosuroides only were exposed to photon irradiance ranging from 0.1 to 25 600 μmol m⁻². Variation was high among seed collections, but both species showed winter annual dormancy patterns. Apera spica-venti germinated to high percentages in autumn but negligibly in spring. Alopecurus myosuroides germinated less in spring when tested in darkness and after a short light exposure and emerged poorly in spring, which reflected photo-desensitisation during cold stratification. We conclude that the peak of emergence in A. myosuroides , and to some extent in A. spica-venti , is largely regulated by exposure to light interacting with low-level dormancy. This offers valuable information regarding optimal timing of weed control measures.     

Relationship between azinphos-methyl usage and residues on grapes and in wine in Australia

Azinphos-methyl was applied to Shiraz winegrapes by commercial high-volume and hand-held sprayers during seasons 1993/94 and 1994/95. Residue levels in grapes resulting from treatments applied by commercial sprayer were below the maximum residue level (MRL) of 2 mg kg^-1 for grapes in Australia, whereas residues resulting from treatments applied by hand-held sprayer still exceeded the MRL five weeks after final application. There was a strong correlation for most treatments between treatment concentration of azinphos-methyl and residue level in grapes, and in wine made from treated grapes. Applied at the recommended rate (1·2 g litre^-1 wettable powder (WP) and 2·4 ml litre^-1 suspension concentrate (SC)) by commercial high-volume sprayer, azinphos-methyl residue levels in wine were well below the MRL, and below the MRLs of most importing countries, except Denmark and Sweden. When applied by hand-held sprayer, residue levels in wine were 5·9–29·6 fold higher than those previously obtained by commercial application of insecticide. Since wines are often blends from different grape blocks and grape-growing districts, in practice, this is unlikely to be of concern. Wine made from grapes treated by commercial sprayer showed no detectable residues of azinphos-methyl after one year of storage. In both years, residue levels in grapes of both formulations of azinphos-methyl fluctuated during the five-week post-treatment period, although there was an overall downward trend. Previously unrecorded systemicity in azinphos-methyl was demonstrated in laboratory studies with barley seedlings, and this may explain these fluctuating data in grapes. The reduction of azinphos-methyl residues in grapes over time appears to be a complex phenomenon involving translocation of active ingredient combined with an increase in the size and weight of berries, producing fluctuating residue levels. © 1998 SCI     

Comparative ecophysiology of grain sorghum and Abutilon theophrasti in monoculture and in mixture

Selection of crop genotypes that are more competitive with weeds for light interception may improve crop yield stability in the presence of weeds. The effects of interference on ecophysiological characteristics of Abutilon theophrasti Medic. and three morphologically diverse grain sorghum hybrids was evaluated to determine the relative tolerance and suppressive ability of the three hybrids and specific traits that may contribute to those differences. A tall hybrid was more tolerant to A. theophrasti interference than two medium stature hybrids. Early leaf area growth of two medium-stature sorghum hybrids was reduced by A. theophrasti interference, whereas early growth of a tall hybrid was unaffected. The height of A. theophrasti was greater than two moderate-stature hybrids but lower than the tall hybrid. Greatest leaf area density (L_D) of the tall sorghum hybrid was above that of A. theophrasti , whereas greatest L_D of medium-stature hybrids was below that of the weed. In monoculture, the partitioning of new biomass to various plant organs was similar among sorghum hybrids, whereas the tall sorghum hybrid partitioned less biomass to leaves and more to stems than medium hybrids in mixture. The results indicate that the three hybrids differ in their susceptibility to A. theophrasti competition. Crop traits that may contribute to greater crop competitiveness include greater maximum height and its growth rate and greater height of maximum leaf area distribution.     

北京地区明代、清代干旱灾害与气候事件研究

根据北京地区历史时期旱灾资料,利用数学统计方法中的参数区间估计研究了明清时期该地区旱灾的差异和气候的不同。结果表明：在北京地区明代（1368-1643年）276年内,共发生旱灾166次,平均1.66年发生1次;轻度旱灾47次,中度旱灾56次,大旱灾55次,特大旱灾8次。在清代（1644-1912年）的269年里,共发生...     

2017年与2014年西安极端高温天气及其环流特征对比分析

借助观测资料与FNL全球分析资料，对比研究2017年与2014年西安高温天气基本特征与有利环流形势，结果表明：① 2 a西安均发生了40 ℃以上的长时间持续高温天气，其中2014年属于常规高温年份，而2017年西安高温则提前1个月发生，高温的提前发生主要是因为南亚高压强于正常年份同期强度；② 不同于我国南方地区的闷湿高温，西安高温属于干性高温，且昼夜温差较小，由此造成24 h对人体的不适；③ 详细描述了西安高温发生的典型环流特征，即南亚高压与西太平洋副热带高压（简称副高）同时增强，并在对流层中高层相互贯通；④ 南亚高压是影响我国西北地区的主要热源基地，在较大经向度的有利环流背景下，强风速可将热气团向南向东深度输送至下游地区（即西安）；⑤ 在“上辐合、下辐散”的散度场配置下，西安500 hPa以下高空维持明显的下沉气流，加之有利的局部要素相配合，最终造成该地区高温天气的发生。