滇中冷凉山区不同播期反季花椰菜产量效益分析

为摸索滇中高海拔冷凉山区反季节栽培花椰菜的最佳播期以集成高效栽培技术推广应用,于2017—2018年选择海拔2250 m的云南省峨山县塔甸镇大西村地块进行9个播期的2年随机区组试验。结果表明,花椰菜生育期随播期推迟而延长,而花球采收期除播期7月10日外随播期推迟而逐渐增长;花椰菜株高、外叶数、开展度、球高、球径和单球重等农艺性状有随播期延迟呈现先逐渐减小而后又逐渐增大的趋势;莲座期黑腐病和霜霉病的病情指数随着播期的延迟呈现先逐渐升高而后又逐渐下降的趋势;花椰菜小区产量随着播期的延迟呈现先逐渐下降而后又逐渐提高的趋势,播期4月20日和4月30日与其余7个播期产量之间的差异达极显著水平。综合花椰菜在冷凉山区反季节栽培的生产实际和各播期产量产值及商品性表现,推荐滇中高海拔冷凉山区反季节栽培花椰菜的最佳播期为4月20—30日。     

安徽沿江地区油麦后直播棉的品种选用策略

在目前安徽沿江地区不能实现棉花机采的情况下,提出了“植株高度既适于机采也适于人工采收,含絮力适中(不易落花便于集中采收),生育期适中(播种到采收为180天左右),纤维品质及产量性状较优(纤维长度30.0 mm以上,断裂比强度30.0 cN/tex以上,马克隆值5.0以下,籽棉产量3750 kg/hm 2以上,衣分在40%左右)”的油(或麦)后直播棉模式的人工采收品种选用策略。旨在促进安徽沿江地区棉花生产稳定发展。     

渭河流域生态功能区划

以渭河流域为研究对象,根据流域生态环境现状,建立合理的指标体系,结合GIS与RS技术对研究区进行区划,并针对各功能区的主导生态功能或主要生态问题制定相应生态环境保护与建设重点。结果表明:渭河流域可被划分为7个生态功能区:①防旱抗旱区;②农业种植区;③牧业发展区;④水源涵养区;⑤防风固沙区;⑥植被保护区;⑦土壤侵蚀控制区。本研究为区域有效开发利用资源,合理制定生态环境保护措施提供科学依据。     

Stability in reproductive timing and habitat usage of Chinook salmon across six years of varying environmental conditions and abundance

The spatial and temporal distribution of spawning activity by autumn‐run Chinook salmon Oncorhynchus tshawytscha (Walbaum) was examined across multiple years. The study period included two years of extreme drought conditions when water temperatures in the spawning reach of the Stanislaus River were considered sub‐optimal for spawning and egg incubation. Despite varying levels of superimposition, redd counts and densities remained stable and positively associated with river location, indicating that superimposition may be driven by habitat preference rather than the absence of suitable spawning locations. Spawning occurred slightly later during drought years (6–10 days later compared with wetter years). This delay was attributable to deferred migration instead of deferred spawning, and the majority of redds were constructed at water temperatures exceeding the optimal temperature range. As a consequence, estimates of juvenile production during 2014 and 2015 were among the lowest on record. These findings may be related in part to the high hatchery contribution to the population, above‐average temperatures during spawning and incubation, and superimposition rates. Management recommendations include adequate cold‐water storage in the upstream reservoir, refined spawning habitat restoration techniques in the light of superimposition rates and, on a broader system scale, actions that reduce the amount of stray hatchery Chinook salmon.     

Assessing the utility of topographic variables in predicting structural complexity of tree stands in a reforested urban landscape

The transformation of natural landscapes into impervious built-up surfaces through urbanization is known to significantly interfere with the ecological integrity of urban landscapes and accelerate climate change and associated impacts. Although urban reforestation is widely recognised as an ideal mitigation practice against these impacts, it often has to compete with other lucrative land uses within an urban area. The often limited urban space provided for reforestation therefore necessitates the optimization of the ecological benefits, which demands spatially explicit information. The recent proliferation of tree stands structural complexity (SSC) and topographic data offer great potential for determining the ecological performance of reforested areas across an urban landscape. This study explores the potential of using topographic datasets to predict SSC in a reforested urban landscape and ranks the value of these topographic variables in determining SSC. Tree structural data from a reforested urban area was collected and fed into a tree stand structural complexity index, which was used to indicate ecological performance. Topographic variables (Topographic Wetness Index, slope, Area Solar Radiation and elevation)- were derived from a Digital Elevation Model (DEM) and used to predict SSC using the Partial Least Squares (PLS) regression technique. Results show that SSC varied significantly between the topographic variables. Results also show that the topographic variables could be used to reliably predict SSC. As expected, the Topographic Wetness Index and slope were the most important topographic determinants of SSC while elevation was the least valuable. These results provide valuable spatially explicit information about the ecological performance of the reforested areas within an urban landscape. Specifically, the study demonstrates the value of topographic data as aids to urban reforestation planning.     

滁河水环境污染防治对策研究

滁河为长江下游左岸一级支流,流经安徽滁州及南京江北地区。滁河既是苏皖两省的交界,又是滁州、南京六合区和浦口区的母亲河。但与此同时,滁河也承担了流域内工业废水、农业废水和生活污水等废水的受纳水体功能。滁河的水环境质量直接影响到滁河流域人民的生活饮用水安全。因此,本研究对滁河进行了水环境质量监测,分析了造成滁河水体污染的主要污染源,并调查了产生过量污染的主要原因,在此基础上提出了针对性的水污染防治对策。     

长江流域生物资源及生态环境研究进展

以CNKI平台中的文献数据,利用文献计量学方法,对其文献的增长趋势及期刊分布进行分析,并基于作者和机构合作网络、关键词共现的聚类知识图谱及突变检测等方法,探究我国长江流域生物资源及生态环境主题的研究热点及其研究前沿。研究表明:研究文献总体上呈递增趋势,2016年开始呈现激增态势;作者、机构间的交流合作较少,作者间合作大部分局限在机构内部的研究者之间的合作,合作相对活跃的机构主要有长江科学院、长江流域水资源保护局及长江水利委员会等;其优势学科领域主要为环境科学、区域经济学、水利工程学、农业经济等。当前我国长江流域生物资源及生态环境的研究领域有5个方向:(1)开展长江经济带城市群生态环境评价与保护、城镇化与生态文明建设,以及绿色发展等研究;(2)开展长江三峡与三峡库区的生态环境监测与保护、森林资源养护、水土保持与流失、资源与生态补偿机制研究及其生态环境的可持续发展等研究;(3)开展长江流域自然保护区的生态环境保护与规划、生态保护红线及其生物资源养护与生物多样性保护等研究;(4)在长江大保护背景下,开展长江流域生态环境的保护与修复、流域综合治理,以及水生生物资源的合理开发利用的研究;(5)开展长江源区水电资源开发、水环境保护及其渔业生态环境保护等研究。为科学管理和保护长江流域的重要生物资源,提出建立基于科学设计的全流域生物资源和环境监测系统,建立全流域的生物资源及生态系统的生物数据模型,发展长江流域渔业资源养护与开发的风险评估决策系统,发展长江流域科学的渔业资源增殖放流技术体系,发展基于GIS的长江全流域的渔业资源与环境监测和管理决策信息服务系统等建议。     

水肥一体化技术在生姜生产中的应用

为了解决生姜生产中存在的费水、过度施肥、营养失衡、人工投入大、生姜产量低和品质不高的突出问题,本研究把水肥一体化技术和生姜生产实践结合起来,从生姜地块的土壤理化性状检测、设备选择与设计、水源选择、肥料选择以及生姜各生育期的水肥投入方案等方面,阐述了水肥一体化技术在生姜生产中的应用技术要点,形成了具有普遍指导性的水肥一体化技术规范。该技术要点体现了水肥一体化的技术优势,可为各生姜产区的生姜生产、广大农技推广人员农技推广服务和农业领域科研工作者提供技术指导和参考。     

延迟收获对长江中游春玉米农艺性状及机收质量的影响

为探明长江中游玉米籽粒机械直收适宜品种与配套农艺措施，2018—2019年选用不同玉米品种，测定不同机收时间下玉米关键农艺性状、产量及机收质量指标。结果表明，收获时间对春玉米机收产量与机收质量均有显著影响。延迟1周收获后籽粒容重显著增加，机收产量显著提高，2年平均提高9.72%；而延迟2周收获则有降低机收产量的趋势。2年收获时杂质率总体≤3%，而机收籽粒破碎率与损失率均>5%，是该区域春玉米籽粒机收面临的主要问题。籽粒厚度、籽粒含水率和百粒重是影响机收籽粒破碎率的关键性状，三者与机收籽粒破碎率均呈显著的倒二次曲线关系；玉米的倒伏率、穗位高和重心高度是影响机收损失率的关键性状，倒伏率与机收损失率呈显著正相关，而穗位高和重心高度与机收损失率均呈显著的二次曲线关系。延迟收获能显著降低籽粒含水量，从而降低籽粒破碎率，但继续延迟收获有增加倒伏的风险。综上，长江中游春玉米成熟后适时延迟7~10 d收获，可有效降低籽粒含水量与机收籽粒破碎率，提高玉米籽粒机收产量。