SiO2纳米颗粒对杉木幼苗生长发育的影响

【目的】近年来,硅对于的植物影响受到人们广泛关注,人们试图将硅确定为植物生长发育的的“必要元素”。因此如何提高植物对硅的吸收利用来增加植物的农艺性状和产量,是当前农业和林业研究的一个重要课题。【方法】以黄枝杉Cunninghamia lanceolata和罗田垂枝杉C.lanceolata var.luotian为材料,采用盆栽的方式,研究施加不同浓度的纳米SiO2颗粒(0、1、2、4 g/盆)对杉木幼苗光合参数、叶绿素荧光、叶片厚度、氮磷钾含量及其分配、生物量累积的影响。【结果】本研究结果显示,SiO2纳米颗粒对杉木根系的生长发育有很大的促进作用,使之能更好的吸收养分,加强了氮磷钾含量的累积。且叶片的厚度也有所增加,在较低的浓度下,气孔导度、光合作用机制、以及光合作用效率增加;地上的生物量也随着施入SiO2纳米颗粒浓度的增加而增加。【结论】我们的实验表明,SiO2纳米颗粒通过促进根系发育加强对营养的吸收和提升叶片厚度,以及提高净光合速率和气孔导度来提高植物的生长机理,进而增加植物的生物量来提升产量。鉴于其对植物生长发育及产量的多种积极影响,硅纳米材料将会为农林植物增产有重要的影响和广阔的前景。     

楼房养猪空气过滤系统设计与应用

土地成本在集约化养殖总成本中占比越来越高,尤其是在城镇化大背景之下。如何显著提高养猪场土地利用率,摊平综合成本,提高土地亩均产出,是整个行业都在考虑的问题。2019年12月17日,自然资源部、农业农村部在《自然资源部农业农村部关于设施农业用地管理有关问题的通知》中指出:"养殖设施允许建设多层建筑",使楼房养猪得到政策支持,但是,配套的楼房养猪空气过滤系统成为亟待解决的问题。文章汲取既往养猪场空气过滤系统设计、应用中积累的经验,为楼房养猪空气过滤系统方案作出综合探究,阐述楼房养猪空气过滤系统设计的理论依据,以及实际应用中需要注意的问题,为逐步实现楼房养猪空气过滤系统标准化提供思路。     

湖北省杉木人工林立地类型划分及评价

以湖北省杉木人工林为研究对象,选择166块具有代表性的杉木人工林标准地,并测定样地的常规立地因子。利用数量化理论Ⅰ的方法建立了杉木优势高与立地因子之间的关系模型,对研究区杉木人工林进行立地类型划分及立地质量评价。结果表明,所选择的5个立地因子与优势高数量化拟合的复相关系数为0.639;海拔、腐殖层厚度和坡位这3个立地因子对优势高的贡献率达84.99%,且影响均达到极显著水平;采用海拔、腐殖层厚度和坡位3个因子构建研究区杉木人工林立地类型,共划分为22类;按照优、良、中、差4个评价等级对166块样地所属的立地类型进行立地质量评价,得出湖北省杉木人工林在中海拔、土壤湿润、土壤养分含量较高的立地条件下生产力较高,研究区立地质量整体处于中等偏上水平的结论。     

Seasonal Changes in Quality and Fatty Acid Composition of Black Mussel (Mytilus galloprovincialis)

The study was designed to assess the seasonal variations in the quality and lipid profile of mussel meat (Mytilus galloprovincialis) harvested along the Bulgarian coast of the Black Sea. The trial period lasted from June to October, and the sampling was carried out in the area of Varna Bay. Technological quality of the mussels was determined by measuring the water holding capacity (WHC) and cooking and roasting losses. Proximate composition, total aerobic plate count, and fatty acid analysis were carried out. Technological parameters and nutritional quality of the mussel meat were strongly affected by the season. During the summer, the mussels had higher mass, meat content, and meat yield (p < 0.001) compared to the early autumn, which corresponds to the lowest protein content during this season. Lipid profile showed seasonal variations in both individual and total fatty acid amounts (p < 0.001). Saturated fatty acids (SFA) had the highest content in summer, while monounsaturated fatty acids (MUFA) decreased gradually until the autumn. The content of polyunsaturated fatty acids (PUFA) reached its peak in October, contributing to the most favorable values of the nutritional indices of lipids in the early autumn.     

小麦赤霉病自动监测预警系统应用效果评价

2018年在江苏、陕西、河南、湖北、安徽共18个县(市)安装了小麦赤霉病预报器,在周边设置未防治麦田进行赤霉病调查,并与预警软件平台预测结果相比较,评价小麦赤霉自动监测预警系统的准确性。评价结果表明,2018年该系统预测的准确性达71.8%。结合陕西省植保总站、西安市植保站、渭南华州区植保站、商洛洛南县植保站、安徽凤台县植保站2016年-2018年对该系统的评价结果,证实该系统预测准确性较高,系统工作稳定,自动化程度高,可为小麦赤霉病的科学防控提供重要的参考依据,具有一定的应用前景。     

国际30年来土壤食物网的研究历程与热点分析

利用文献计量学方法,研究1989—2018年来土壤食物网研究领域的热点内容,概括土壤食物网的研究脉络及国际土壤食物网未来的研究方向。结果显示:土壤生物多样性、食物网的碳氮循环功能及管理方式对土壤食物网结构的干扰是现在研究热点,而土壤食物网功能多样性、系统稳定性、及土壤食物网对全球变化的响应则是新兴的研究方向。     

关中-天水经济区人类活动对植被覆盖变化的影响

为探究植被覆盖变化及人类活动对改善关中地区及西北地区的生态环境影响,利用植被覆盖和地表温度数据,结合Sen趋势与Mann-Kendall检验分析关中-天水经济区2001—2016年的植被覆盖变化趋势,并根据估算的土壤湿度因子,应用残差法评价人类活动对植被覆盖变化的影响程度及影响方向。结果表明:1)从时间变化维度来看,2001—2016年关中-天水经济区植被覆盖变化总体呈良好趋势,且整体表现为在不断波动中递增,表明关天经济区进行的生态环境建设工程正在慢慢凸显它的生态效应。2)从空间变化维度来看,关中-天水经济区植被覆盖显著增长的区域面积占35.87%,主要集中在研究区南北两侧。而显著下降的面积区域占3.21%,主要分布在城市中心,即经济发展活跃的地区,如西安市区,宝鸡市区,天水市区,铜川市区等。3)关中-天水经济区植被覆盖受自然因素影响较小,受其他因素影响大。其正相关区域占13.43%,不显著相关区域占85.26%。4)关中-天水经济区人类活动对植被覆盖变化的正作用大于负作用。其中,正作用区域主要分布在研究区北部和东南地区,其主要原因是人类活动不频繁,建设生态屏障、加强退耕还林、三北防护林保护以及水土保持等生态工程促进植被NDVI增长。负作用区域主要分布在渭河沿线、经济活动较高地区,其主要原因有:人类活动频繁、过度城市化、工业化等抑制植被生长。5)植被覆盖的增长和下降区域与人类活动对植被影响的正作用和负作用区域大致相同。这也从侧面反映了关天经济区植被覆盖情况受人类活动影响大。总之,在负作用区域,在经济建设发展的同时也要注重植被建设、以及对植被乃至生态环境的保护。     

Impacts of diet on hindgut microbiota and short‐chain fatty acids in grass carp (Ctenopharyngodon idellus)

Diet is known to influence intestinal microbiota in fish, but the specifics of these impacts are still poorly understood. Different protein/fibre ratio diets may result in differing structures and activities of gut microbiota. We examined the hindgut microbiome of grass carp (Ctenopharyngodon idellus) fed three different diets: fish meal (FM, high protein – low fibre), Sudan grass (SG, high fibre – low protein) and compound feed (CF, intermediate). Microbial profiles of fish fed on FM were significantly different from profiles of fish fed CF and SG (F = 18.85, p < .01). Cetobacterium, known to be positively associated with protein digestion, was the dominant microbial group in FM samples (approximately 75.7%), while Lachnospiraceae and Erysipelotrichaceae, thought to be involved in fermentation of plant polysaccharides, were dominant in CF and SG samples (46.8% and 42.9% respectively). Network analyses indicated that the abundance of Lachnospiraceae and Erysipelotrichaceae was in a significantly positive correlation (r = .895, p = .001). Short‐chain fatty acid (SCFA) levels may indicate that the digestibility of diet by microbiota in the grass carp gut decreased from FM to SG (FM>CF>SG). Overall low SCFA levels indicate that hindgut fermentation probably provides a low proportion of energy requirements in grass carp.     

Effects and mechanisms of rural E-commerce clusters on households' entrepreneurship behavior in China

The vigorous development of rural E-commerce reveals a powerful pattern of economic clustering. Recently, many Taobao Villages have formed in more than 80% of the provinces in rural China, and increasingly households are using E-commerce for entrepreneurial innovation in Taobao Villages. However, the effect and mechanism of the Taobao Village model on households' entrepreneurship behavior remain unclear. Using survey data and structural equation modeling, we analyzed the factors of households' entrepreneurship behavior and investigated the mechanism of rural E-commerce clustering on the households' entrepreneurship behavior in Taobao Villages. The results show that: (1) rural E-commerce clusters stimulated entrepreneurial enthusiasm and increased entrepreneurial behavior; (2) local resource endowment, entrepreneurial atmosphere and culture, threshold for entrepreneurship, and demonstrative leadership had significant positive effects on households' entrepreneurship behavior; (3) external environmental support, including government, and external business environment support had significant positive effects on E-commerce development. All these results indicate that rural E-commerce clusters promote households' entrepreneurship behavior.