施用不同氮肥对盐碱地湖南稷子生产性能以及养分吸收的影响

为探讨盐碱地湖南稷子(Echinochloa frumentacea)高效生产的最佳施氮种类和施氮量,采用单因素随机区组设计,通过在湖南稷子拔节期设置不施肥(CK)、尿素和硫酸铵(N1,N2)轻施肥(F1:50 kg·hm^-2)、中施肥(F2:100 kg·hm^-2)、重施肥处理(F3:150 kg·hm^-2),研究不同氮肥和施氮水平下湖南稷子田间农艺性状、养分吸收及氮肥利用率的变化,探讨盐碱地湖南稷子实现高效生产的适宜氮肥和施氮量。结果表明：与对照相比,施氮量为F2和F3时能够显著提高盐碱地湖南稷子产量及氮磷钾吸收量(P<0.05),植株不同部位氮含量上升,施氮量F3时能够显著提高氮肥利用效率(P<0.05),且同一施氮量下追施硫酸铵后湖南稷子产量、养分吸收及氮肥利用率均高于尿素。综上所述,氮肥追施量在150 kg·hm^-2时,有利于盐碱地湖南稷子的产量的提升和养分的吸收,且同一条件下追施硫酸铵较追施尿素效果显著。     

多梯度氮磷添加对高寒草甸植物群落生物量与氮磷含量的影响

为研究不同梯度氮、磷单独及混合添加对高寒草甸植物群落生物量、植物养分含量及化学计量比的影响,本实验分析了青海省门源县典型高寒草甸植物群落地上总生物量,功能群水平地上生物量,植物全氮、全磷含量及氮磷比对多梯度氮、磷添加的响应情况。结果表明：氮、磷添加均对群落地上生物量影响极显著(P<0.001);氮添加对禾草类和豆科生物量影响极显著(P<0.001);磷添加对禾草类和莎草类生物量影响极显著(P<0.001);氮磷交互作用对豆科和莎草类生物量影响显著(P<0.05)。群落水平上,氮添加显著提高了植物全氮含量,对植物氮磷比(N∶P)有正效应,磷添加显著提高了植物全磷含量,对植物N∶P有负效应,植物全磷对N∶P的负效应大于全氮对N∶P的正效应。本研究表明氮、磷添加可能会使高寒草甸植物群落组成和植物养分含量发生改变,植物群落逐渐向禾草类发展;此外,高寒草甸植物生长趋向于受氮磷共同限制。     

银杏叶提取物对发酵乳贮藏期理化和感官特性的影响

[目的] 考察不同添加量银杏叶提取物对发酵乳贮藏期品质的影响。[方法] 采用持水率、黏度、乳酸菌活菌数、抗氧化能力、感官评价方法测定不同添加量银杏叶提取物制备的发酵乳,并结合多元统计分析方法进行分析。[结果] 银杏叶提取物对乳酸杆菌和链球菌的活力没有显著影响,为保证活菌数在1.0×10⁷ CFU/g以上,建议该发酵乳最多冷藏9 天。在酸奶中添加银杏叶提取物可提高其抗氧化特性。添加银杏叶提取物的酸奶样品与对照组在风味和口感方面存在差异,且添加量越大差异越明显。[结论] 银杏叶提取物本身作为一种中成药,具有成为一种新的功能性酸奶成分的巨大潜力。     

PGPR对灰枣土壤养分及微生物数量影响的主成分分析

为了得到有益于灰枣生长发育的优势菌种,通过田间试验,研究了灰枣根际促生复合菌株P13K7、P13K24和单一功能菌株P13、P15、K7、K24以及对照(CK)7个处理对灰枣根际土壤养分和微生物数量的影响。应用主成分分析法,将8个指标(p H值、有机质含量、碱解氮含量、速效磷含量、速效钾含量、细菌数量、放线菌数量和真菌数量)简化成2个主成分,2个主成分所提供的信息量占全部信息量的90.78%。结果表明:与对照相比,施用PGPR能够改善灰枣土壤养分和提高微生物总量。经过土壤指标的综合分析得出,复合菌株P13K24的应用效果最好。     

太行山片麻岩山地坡面土壤含水率及其影响因子——以河北省阜平县为例

为了解决太行山干旱片麻岩山区极度缺水问题,以河北省太行山片麻岩山区的典型地区阜平县为试验基地,研究了坡向(X1)、坡位(X2)、坡度(X3)、土层厚度(X4)、土壤容重(X5)、土粒密度(X6)、植被覆盖度(X7)、田间持水量(X8)、毛管孔隙度(X9)、土壤质地(X10)等因素与土壤含水率(y)的关系。结果表明:该地土壤含水率极低,仅为3.18%~8.61%;上述因素与土壤含水率的相关系数分别为0.745,0.612,-0.078,0.992,-0.924,-0.693,0.974,0.834,0.798,0.918;除与坡度相关不显著外,其他因素均显著或极显著相关;主成分分析筛选出坡向、坡位、土层厚度、土壤容重、植被覆盖度等5个因子对土壤含水率影响最大;直接通径系数绝对值大小排序为土层厚度(0.609)>植被覆盖度(0.224)>土壤容重(-0.185),结合间接通径系数和相关系数来看,土层厚度、植被覆盖度、土壤容重均对土壤含水率有较大影响,其中土层厚度和植被覆盖度为正效应,土壤容重为负效应。     

Growth and nutrient accumulation of Brazil nut trees (Bertholletia excelsa) in agroforestry at different fertilizer levels

The Brazil nut tree(Bertholletia excelsa) is a frequent component of agroforestry systems in the Amazon because of its adaptation to nutrient-poor upland soils and multiple uses.We investigated the aboveground biomass production(kg dry weight),nutrient uptake and requirements(N,P,Ca,Mg,K) of Brazil nut trees of different sizes grown under agroforestry conditions and fertilized at different levels.Eight of 70 experimental trees with different size were harvested and stem,branches and leaves were separated.Nutrient contents were determined for three trees of varying size.Average tree growth was fast,but variability was high,suggesting considerable potential for the improvement of this economically important species.The trees responded to increased levels of fertilizer and lime with significantly increased foliar nutrient contents and growth,probably because of the improved availability of Mg and Ca for which the species seems to have a relatively high demand.In contrast to Brazil nut trees grown in forest or dense plantations,the agroforestry trees invested a substantial part of their biomass and nutrients in large branches and developed spreading crowns.To improve stem form,reduce competition with associated crops for light and recycle nutrients,regular pruning of lower branches or planting arrangements that favor self-pruning are recommended.These measures would also increase the recycling of Ca and Mg,large quantities of which are contained in the branches.     

Mass balanced based LCA of a common carp-lettuce aquaponics system

An aquaponics system (AS) is an integrated system that combines a recirculating aquaculture system and a hydroponics system (HS). It is designed to recover nutrients released from fish and transfer them to plants to provide a system more environmentally-friendly than the two systems working separately. As a result, several AS are under development, but little information is available about their overall performances. The aim of this study was to assess nutrient-use efficiency and environmental impacts of an AS, specifically a common carp-lettuce AS located in a greenhouse. Nutrient budgets of nitrogen (N) and phosphorus (P) were calculated and Life Cycle Assessment (LCA) was performed for the AS and for a lettuce Individual Hydroponics System (IHS), similar to the HS of the AS, operating in the greenhouse at the same time. The experiment was performed over a 52-day cycle, which corresponds to the growing time required to harvest marketable lettuce. The nutrient budgets were well balanced, with 24.6% of the N unaccounted-for, most likely due to N2 gas emission, and 6.6% of the P unaccounted-for, most likely due to having underestimated the quantity of sediment. At the beginning of the experiment, N represented 55.9%, 37.1% and 0.1% of the total N input in the formulated feed, stocked fish and lettuce seedlings, respectively. At the end of the experiment, N represented 47.6% and 0.4% of the total N input in the harvested fish and lettuce, respectively. At the beginning of the experiment, P represented 56.94%, 40.20% and 0.03% of the total P input in the formulated feed, stocked fish and lettuce seedlings, respectively. At the end of the experiment, P represented 51.52% and 0.42% of the total P input in the harvested fish and lettuce, respectively. LCA clearly indicated two environmental impact hotspots: the origin of nutrients and energy use. One kg of lettuce growth in the AS clearly had lower environmental impacts than that in the IHS for climate change, acidification, eutrophication, land competition and cumulative energy demand; however, a decrease in water dependence was not observed. The indicator for net primary production use highlighted the dependence of the AS on natural resources, especially fish meal and fish oil. Compared to the use of chemical nutrients in the IHS, the use of nutrients from formulated feed in the AS decreased climate change impact but increased the use of natural resources.     

不同产地鲍鱼特征元素分析与主成分评价模型的建立

为了找出不同产地鲍鱼(Haliotis Spp.Abalone)的区域性差异,并探究一种有效的鲍鱼产地的鉴别方法,采用主成分分析法对对广东、福建、山东、辽宁4个主要养殖省份鲍鱼样品肌肉中的特征元素(Na、K、Mg、Ca、Fe、Zn、Cu、Ni、As、Al、Mn、Cr、Se)进行分析。结果显示,鲍鱼样品的元素含量存在差异,Mn的变异程度最大,变异系数为74%,Ni次之,为65%,其次是Se (60%),其余元素的变异系数均高于10%。同时,通过对这些数据进行降维处理,有效地从13个特征元素中提取了6个元素作为主成分,累计方差贡献率达89.87%;同时发现Ca、Se、Na、Fe、Mn、K、Ni这7种元素是不同产地鲍鱼的特征元素,并建立了主成分综合评价模型:F=0.2777F_1+0.2652F_2+0.1295F_3+0.1066F_4+0.0656F_5+0.0541F_6。模型的建立可以为利用特征元素对不同产地鲍鱼的产地溯源提供一定的理论参考。     

青贮玉米品质性状遗传变异及主成分分析

为了鉴定青贮玉米品质性状间的相关和依附关系,对14份青贮玉米材料的22个品质性状检测分析,并进行一般描述统计、遗传变异、相关性及主成分分析。结果表明,参试青贮玉米各品质性状中,脂肪、钾、木质素、淀粉含量的变异系数较大,分别为0.20、0.19、0.17和0.16,表明这些性状在品种遗传选育进程中有较大的改良空间;消化率及能量品质相关性状的变异系数介于0.03~0.08,表明这部分性状难以得到遗传改良;青贮玉米品质性状间相关性较大,适宜采用主成分分析保留品质性状的最重要方面。对测试的22个品质性状进行主成分提取,前3个主成分的累积贡献率达到91.29%,分别代表了青贮玉米的饲用价值、微量元素及粗蛋白成分。