小型西瓜生育特性与保护地栽培技术

小型西瓜生育特性、种植模式与普通西瓜不同,种植过程中容易出现问题。基于小西瓜的生育特性,综述北方地区保护地栽培的主要技术要点,为提高小型西瓜的产量和品质提供参考。     

TCD燃烧系统对柴油机燃烧和排放性能改善效果的试验研究

为探究道依茨TCD2015柴油机上配备的导流燃烧系统(简称TCD燃烧系统,T表示涡轮增压器,Turbocharger,C表示进气中冷,Charge air cooling,D为柴油颗粒捕集器,Diesel particle filter)对改善柴油机燃烧性能和降低污染物排放的效果,采用单缸机试验对TCD燃烧系统在不同转速、负荷和过量空气系数下的燃烧和排放性能进行研究。试验结果表明不同工况下TCD燃烧系统燃油消耗率和Soot排放量均低于传统ω燃烧系统,燃油消耗率最大降幅为7.01%,Soot排放量最大降幅为86.67%,且低过量空气系数(1.2～1.6)下TCD燃烧系统仍具有较好的性能。为揭示TCD燃烧系统改善油气混合促进燃烧的机理,采用AVL Fire软件建立了柴油机性能仿真模型。计算结果表明,TCD燃烧系统的环状凸起结构将燃油导向内外两室,从而促进了缸内燃油发展过程,燃油当量比大于4的浓混合气区域燃油质量比例相比ω燃烧系统降幅最大为9.75%,活塞下移时TCD燃烧系统内油束撞击浅盘侧壁形成撞壁射流扩大了燃油扩散面积,从而改善了缸内油气混合质量,燃油当量比小于1的均匀混合气区域燃油质量比例相比ω燃烧系统降幅最大为7.45%,因此TCD燃烧系统能够有效改善柴油机的燃烧和排放性能,可应用于柴油机高负荷和低过量空气系数工况综合性能提升。研究结果可为柴油机燃烧系统开发和改进提供参考。     

甜菜BvGSTU9基因的生物信息学及在镉胁迫下的表达分析

为了进一步研究甜菜谷胱甘肽转移酶BvGSTU9 (LOC104894060)在重金属胁迫过程中的功能。本研究以‘780016B/12优’为实验材料,对该基因序列特征、结构、功能进行预测分析,并利用qPCR检测该基因在不同浓度镉胁迫下的表达量变化。结果显示甜菜BvGSTU9基因全长925 bp,开放阅读框675 bp,编码了由224个氨基酸组成的不稳定膜外蛋白。BvGSTU9与菠菜、藜麦的氨基酸序列相似性较高,与系统发育进化树分析结果基本相符。二级和三级结构预测表明该基因主要由α-螺旋、β-折叠、延伸链及无规则卷曲组成。qPCR显示BvGSTU9基因在不同浓度的镉胁迫下均受到不同程度的诱导,因此可以推断甜菜BvGSTU9基因无论从结构还是功能上,与镉逆境胁迫存在着一定的应答关系。研究结果也为甜菜耐重金属镉机制研究提供参考依据。     

宽甸地区林业资源及其特色产业发展研究

综述宽甸地区自然条件和林业资源概况,介绍林业特色产业的规划布局和建设现状。基于生态文明的发展理念,根据林业资源的特点和优势,提出进一步发展特色林业产业的可行性建议,为充分发挥宽甸地区林业资源潜力提供借鉴。     

极小种群植物“川柿”生物学特性及种子萌发方法研究

摘 要：【目的】为了保护和发展极小种群植物川柿，开展此研究。【方法】采用观测法，连续3年对其生物学特性研究；种子萌发方法：（1）后熟0、30、45、60天，剥离清洗播种；（2）后熟60天，以GA300、600、1000 mg/L溶液浸种1h；播种基质为河沙（保持一定湿度），放置室内，统计萌发时间和出苗率。【结果】（1）川柿花期4-5月，10月为果熟期，单果直径32.7±5.80mm，单果重23.0±5.30g；种子肾形、千粒重1070g；成年植株呈隔年开花、结果现象；（2）种子经“后熟+河沙播种”，可萌发，其中以后熟60天的出苗率较高，为65%；直接播种种子，出苗率5%；“后熟+GA溶液浸种+河沙播种”，出苗率均高于65%，其中以GA600mg/L浸泡1h处理，出苗率最高为83.3%。【结论】极小种群植物川柿为常绿叶乔木，有隔年开花、结果现象； “果后熟60天+GA600mg/L浸泡种子1h +室内河沙播种”可提高种子萌发率，为川柿种子繁殖提供参考。     

不同种植密度对3个小豆品种植株形态及产量的影响

采用两因素随机区组设计,以直立型小豆品种冀红20、冀红21和唐红201602为材料,分析6个种植密度对不同小豆品种植株形态特征及产量性状的影响。结果表明,品种和种植密度对小豆形态特征和产量性状的影响较大;底荚高度和第一节间长随着密度的增加而增加,主茎节数、主茎分枝数、单株结荚数、单荚粒数和百粒重随着种植密度的增加而减小,产量随种植密度的增加呈先增加后减少趋势;相同品种不同种植密度间和相同种植密度不同品种间的产量差异极显著（F值分别为49.36、99.35）,品种与种植密度互作对产量的影响差异显著（F=3.91）。种植密度与株高、底荚高度呈极显著正相关,与第一节间长呈正相关,与茎粗、主茎分枝数和主茎节数呈极显著负相关。增加种植密度可增加小豆株高、底荚高度和第一节间长,有效减少主茎分枝数,有利于机械化收获。     

Growth and biomass partitioning of nine provenances of Quillaja saponaria seedlings to water stress

Information on the morphological and physiological responses of seedlings to stressors, such as water stress, is required for successful early establishment of seedlings. We examined provenance variation in morphological and physiological traits of Quillaja saponaria Molina seeds from nine provenances representing a latitudinal transect across the species range in Chile. The seedlings were subjected to two water regimes (well-watered vs water restriction) in a nursery experiment, and growth, biomass, survival, and gas exchange traits were measured. As expected, well-watered seedlings exhibited a superior performance in all traits analysed. Provenance effects were significant for most of the morphological and physiological traits. In the growth and biomass analysis, the northernmost provenance showed the lowest survival, growth and dry biomass, whereas in the gas exchange analysis, the southern interior provenance showed the highest net photosynthesis, transpiration, stomatal conductance and water use efficiency. The interaction between water regimes and provenance was only significant for diameter and net photosynthesis. These results indicate that different provenances of Q. saponaria show a stable performance across different controlled drought conditions. This information is of relevance for sourcing seeds for the restoration of the species.     

Projecting the suitability of global and local habitats for myrtle rust (Austropuccinia psidii) using model consensus

Myrtle rust (caused by Austropuccinia psidii) affects more than 500 known host species in the Myrtaceae family. Three different modelling approaches (CLIMEX, MaxEnt and Multi-Model Framework) were used to project the habitat suitability for myrtle rust at both global and local scales. Current data on the global occurrence of myrtle rust were collected from online literature and expert solicitation. Long-term averages of climate data (1960–1990) were sourced from WorldClim and CliMond websites. Recent reports of myrtle rust in New Zealand were used for validation of model outputs but not in model training and testing. The model outputs were combined into a consensus model to identify localities projected to be suitable for myrtle rust according to two or three models (hotspots). In addition to the locations where the pathogen is currently present, all models successfully projected independent occurrence data in New Zealand suitable for establishment of the pathogen. Climate suitability for the pathogen was primarily related to temperature followed by rainfall in MaxEnt and the CLIMEX model. The results confirmed the optimum temperature range of this pathogen in the literature (15–25 °C). Additional analysis of the precipitation variables indicated that excessive rain (more than 2000 mm in warmest quarter of the year) combined with high temperatures (>30 °C) constrain pathogen establishment. The results of the current study can be useful for countries such as New Zealand, China, South Africa and Singapore where the pathogen has not fully spread or established.     

Dissolved oxygen controls summer habitat of Clear Lake Hitch (Lavinia exilicauda chi), an imperilled potamodromous cyprinid

Clear Lake Hitch is an imperilled minnow endemic to Clear Lake, Lake County, California, United States listed as threatened under the California Endangered Species Act (ESA) and a candidate for listing under the United States ESA. It exhibits a potamodromous life cycle whereby adults, which reach up to 6 + years in age and over 350 mm in length, migrate into Clear Lake's ephemeral tributaries briefly during spring to spawn. Conservation and management of Clear Lake Hitch is inhibited, in part, by a lack of information on the lacustrine habitat of nonbreeding individuals within Clear Lake. To address this problem, we sampled Clear Lake Hitch with gill nets in a stratified random sampling design to determine the distribution and habitat associations in early summer 2017 and 2018. We identified abundance-habitat relationships for juveniles and adults using Bayesian zero-inflated negative binomial generalised linear mixed modelling. Results indicated that dissolved oxygen concentration was the most important habitat feature measured; juveniles and adults were substantially more abundant in normoxic (≥2 mg/l) than in hypoxic (<2 mg/l) habitat. Both also exhibited weak positive relationships with chlorophyll fluorescence, suggesting relatively productive habitats may support higher numbers of Clear Lake Hitch. Spatially, juveniles were most abundant in nearshore habitats while adults were ubiquitous, indicating an ontogenetic habitat expansion that may be associated with a resource availability-predation risk trade-off. Management actions undertaken to improve hypoxia problems in Clear Lake would also improve Clear Lake Hitch habitat.     

拉丁美洲和加勒比地区主要竹种资源与利用

拉丁美洲和加勒比地区是世界主要的竹资源分布区，以瓜多竹为代表的560多竹种资源占全球竹种的33%，其中巴西、哥伦比亚、秘鲁、厄瓜多尔、墨西哥等国竹林面积和竹种数量位居该地区前列。与亚洲相比，拉丁美洲和加勒比地区现代竹产业发展起步较晚，规模和效益有限。面向未来，该区竹资源主要分布国家的政府正在制定和实施相关政策和战略，助力竹区发展经济、缓解贫困和保护环境。