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81.
Synthetic aggregates (SA) were developed using low productive red soil, paper, and starch waste and then utilized as a soil ameliorant to improve poor physical and chemical properties of a gray soil (“Jahgaru”). The gray soil was amended with SA at 10, 20, 30, 40, and 50% and then used for the cultivation of French marigold (Tagetes patula). The SA addition enhanced bulk density, porosity, water‐holding capacity, hydraulic conductivity, pH, organic matter, and carbon (C) content of original gray soil. Plant height, number of flowers per plant, shoot fresh weight, shoot dry weight, root length, root fresh weight, and root dry weight in 30% of SA addition were the greatest and were increased by 1.5, 2.9, 3.5, 4.7, 3.4, 4.3, and 9 times, respectively, compared to gray soil. It can be concluded that developed SA can be utilized as a soil ameliorant to improve poor physical and chemical properties of gray soil.  相似文献   
82.
Wind erosion is a major contributor to desertification in the Sahel. Although three effective countermeasures for wind erosion (i.e. ridging, mulching with post-harvest crop residue, and windbreaks) have been proposed, they are not practical for Sahelian farmers. Therefore, we designed a new land management practice, termed the “Fallow Band System,” which can be used for both controlling wind erosion and improving soil fertility and crop production. This method does not impose additional expense and labor requirements on Sahelian farmers who are economically challenged and have limited manpower. The objective of this study was to evaluate the effects of this system on wind-erosion control and soil-fertility improvement. We conducted field experiments at the International Crops Research Institute for the Semi-Arid Tropics West and Central Africa and showed that (i) a fallow band can capture 74% of wind-blown soil particles and 58% of wind-blown coarse organic matter, which suggests that it can effectively control wind erosion, (ii) the amount of soil nutrients available for crops in a former fallow band was increased by the decomposition of trapped soil materials containing considerable amounts of nutrients, and (iii) the amount of soil water available for crops in a former fallow band was increased by the trapped wind-blown soil materials through improvement of rainwater infiltration into surface soil. These results lead to the conclusion that the “Fallow Band System” can be useful for preventing desertification and improving soil fertility in the Sahel, West Africa.  相似文献   
83.
Maize plants, grown for 7 and 21 days on a nutrient solution with NO3 as the sole nitrogen source showed a clear diurnal pattern with respect to the in vivo NRA. Especially in roots dark/light fluctuations of the enzyme activity were high. Also in NO3 uptake, OH efflux and endogenous content of water soluble carbohydrates a diurnal variation was found. The plant age did not significantly affect the daily rhythm.

Because day/night changes of the in vivo root NRA and nitrate uptake were proportional, the relative content of reduced N in the xylem sap of the plants was constant during a day/night interval. At both day 7 and day 21 about 40–50% of the N was transported via the xylem as amino N. As a result of non‐synchronous variation of the specific root and shoot NRA, root reduction capacity showed a great within‐day variation. It varied between 20 and 40% of the whole plant reduction capacity. Since the ratio N‐organic to N‐total in the xylem sap was about 0.5, cycling of organic nitrogen was very likely in these maize plants.  相似文献   
84.
为研究补播对高寒草地群落特征和植被多样性的影响,本研究以黑土滩中度退化草地为对象,利用免耕补播机通过近自然补播措施进行了恢复,测定了恢复后草地的群落组成及多样性特征。结果表明:经人工补播后,退化草地的植被盖度,地上、地下生物量,禾本科牧草比例和根冠比都显著上升(P<0.05),补播措施起到了很好的修复效果。从物种组成上看,退化草地经过补播之后,其植被群落组成和物种重要值都发生了变化。其中,禾本科牧草和莎草科牧草占据了重要地位。此外,物种丰富度指数、Shannon-Weiner指数、均匀度指数经人工补播后都有所上升,但差异不显著。综上所述,人工补播是高寒地区黑土滩中度退化草地修复一种快速有效的措施,能够有效的提高可食牧草的比例,同时也有利于高寒地区草地植被恢复。  相似文献   
85.
LI Xiao-min;NING Xiao-yun(Jiangxi Provincial Forestry Planning and Designing Institute,Nanchang,Jiangxi330046)  相似文献   
86.
邴静静  高红梅  王誌达 《作物研究》2019,(5):482-486,510
近年来,农村电商发展迅猛,已成为促进农民增收、扩宽农产品销售渠道、推动农业转型升级的重要力量.但目前,农产品市场基础设施建设水平落后,产品品牌意识薄弱,产品综合质量不高.因此,中国农业需要探索新的发展道路,创新农产品品牌,提升农产品附加值,开拓农业新的发展方式,使农民从互联网中受益.基于此背景,以天津"小站稻"为例,从微观角度出发,在实地调查的基础上,综合运用品牌价值来推广农产品.提出在电子商务视角下,推动天津"小站稻"品牌增值的建议,让农村电子商务成为农村发展的新动力,对推动农业供给侧结构性改革具有深远意义.  相似文献   
87.
孔子向内构建认知结构,以"德"、"才"、"行"为核心支撑因素,设立了"君子"的个体德育目标。"君子"内化于"仁",外化于"礼"。由"君子"上推,"君子"向外协调社会关系,以"仁"与"礼"治人,完成建立社会秩序的历史使命,从而设立了"有道"的社会德育目标。如此层层递进,自下而上地构建了一个个体德育目标和社会德育目标密切联结的德育目标体系。  相似文献   
88.
为了探究急性高温胁迫对大口黑鲈“优鲈3号”凋亡相关酶活性和基因表达的影响,将25℃下暂养的大口黑鲈“优鲈3号”直接放入37℃水环境中,探究急性高温胁迫后幼鱼肝脏组织Caspase3、Caspase9和基因酶活的变化。结果显示:37℃高温胁迫后,肝脏Caspase3和Caspase9酶活均显著升高,且随着胁迫时间的延长呈升高趋势,在48 h达到峰值。基因Caspase3和Caspase9的表达量均呈现先升高再下降的趋势,在6 h的表达量达到峰值,随之下降,并在48 h与对照组无显著性差异。BCL-2的表达量于1 h达到峰值,之后显著下降,48 h时BCL-2的表达量仅为对照组的0.04倍。结果表明,高温胁迫会使大口黑鲈“优鲈3号”幼鱼发生凋亡甚至细胞坏死。  相似文献   
89.
为了解池塘养殖条件下1龄异育银鲫“中科3号”的生长特性,在池塘自然水温(18.5~30.6℃)条件下,对体长(4.53±0.18)cm、体质量(2.73±0.17)g的1龄异育银鲫“中科3号”的生长性能进行了研究。试验结果:经过125 d培育,异育银鲫“中科3号”体长增长237.53%,体质量增长3312.45%;体长与体质量呈幂函数关系,关系式为W=0.0356L2.8885(R2=0.985),属等速生长型;体质量日增长量从试验开始到100 d始终呈增高态势,75~100 d的平均体质量日增长量为最高值(1.346 g/d),之后随着水温下降而降低;体质量相对增长率在0~25 d为最高(269.60%),而后逐渐降低,至125 d试验结束时为30.37%;生长指数(0.1054~0.4647)和生长常数(1.318~5.809)随着试验的进行逐渐降低;肥满度为2.6062~2.9480 g/cm^3,呈先降低、后升高、再降低的小幅波动;生长离散逐渐小幅增加。  相似文献   
90.
文章从“互联网+”环境带来的机遇与挑战出发,分析社会用户需求的规律与特点,分别从宏观层面与微观层面分析图书馆社会服务信息资源的组织与建设,包括网络资源与图书馆资源的组织整合、图书馆内部异构资源的组织整合、图书馆联盟间的资源的组织整合、基于用户参与的社会化信息资源创建与组织和个性化信息组织。最后指出图书馆应汲取“互联网+”环境营养,建立多模式并存协调发展的信息知识组织体系,提供真正面向用户的服务产品,提升高校图书馆的社会服务水平。  相似文献   
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