Diurnal variations in uptake,transport and assimilation of NO3 ‐and efflux of OH‐ in maize plants

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.     

电子商务视角下天津“小站稻”品牌价值提升策略研究

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.     

“Fallow Band System,” a land management practice for controlling desertification and improving crop production in the Sahel,West Africa. 1. Effectiveness in desertification control and soil fertility improvement

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.     

基于移动互联网的快速“三农”信息交互平台研究

针对农民与“三农”专业人员能及时方便互通的需求,设计以移动互联网的微博、飞信等为载体的快速信息交互平台模型,该平台模型降低了农民信息交流的门槛,只需要手机即可,简捷快速低廉,可在田间地头以信息、拍照的形式咨询专家群的建议.在三农信息建设中具有一定应用价值.     

华杂四号油菜最佳施肥模型及经济效益分析

通过对华杂四号油菜的施氮量、施磷量、施钾量和施硼量的研究 ,找出了对华杂四号油菜产量影响较大的试验因子是 :施氮量、施磷量和施硼量。并利用频数分析法 ,通过计算机模拟寻优 ,建立了华杂四号油菜在淮南稻区 30 0 0kg/ha以上的优化栽培模型     

海岛棉不同果枝品种间杂交产量性状的遗传及F1和F2群体优势分析

采用MINQUE（1）统计方法及AD模型对9个海岛棉品种（系）及其20个F1组合9个产量性状的两年资料进行了遗传分析。结果表明，海岛棉长果枝与零式果枝品种间杂交，各产量性状均存在极显著的加性效应方差比例；衣分、铃重、霜后铃数、总铃数和皮棉产量存在极显著的显性效应；均存在显性与环境的互作。品种3836具有霜前铃数和霜前     

大气CO2浓度升高与氮肥营养对滴灌棉田“棉花-土壤”系统氮分布的影响

通过半开顶式CO2人工气候室,研究了CO2浓度升高（360、540μmol·mol－1和720μmol·mol－1）与不同氮肥营养（0、150、300 kg·hm－2和450 kg·hm－2）相互作用对蕾铃期棉花－土壤氮含量变化及棉花氮素吸收的影响,结果显示：大气CO2浓度增加,高氮肥处理下棉花叶片、蕾铃中氮含量显著降低,茎秆、根系中氮含量增加,棉花整株氮含量表现为下降;相同的CO2浓度下,随着氮素营养的增加棉花各器官氮积累量呈增加趋势,其中蕾铃、叶片氮积累量较高,茎秆、根系氮积累量相对较少,说明CO2浓度增加与增施氮肥促进了土壤氮素向植株叶片和生殖器官运输。通过对土壤无机氮含量的测定分析,CO2浓度升高为540μmol·mol－1,各施氮水平下棉田土壤NO3－-N含量显著降低,NH4＋-N含量在低氮水平下有少量增加,在高氮水平下表现为降低;CO2浓度升高为720μmol·mol－1,土壤NO3－-N含量表现为降低,NH4＋-N含量呈增加趋势。研究表明：大气CO2浓度增加且浓度范围在500～720μmol·mol－1,增加氮肥施用量可有效促进棉花对氮素养分尤其是NO3－-N的吸收利用。     

区域灌溉水利用率影响主因分析

基于各省(市、区)灌溉水利用率的动态变化,采用SPSS19.0软件分析了“十一五”期间我国不同分区区域灌溉水利用率的关键影响因素.结果表明,6大分区不同灌区平均灌溉水利用率均受到社会经济发展水平(GDP)的显著影响.此外,区域平均灌溉水利用率在华北地区受纯井灌区有效灌溉面积的显著影响,东北地区受小型灌区有效灌溉面积的显著影响,东南地区受大型自流灌区毛用水量的显著影响,中部地区受纯井灌区及小型灌区有效灌溉面积的影响,西南地区受节水灌溉工程控制面积的显著影响,西北地区纯井灌区有效总灌溉面积显著影响该地区平均灌溉水利用率.     

“天骄”液肥在水稻增产上的应用研究

用不同浓度的“天骄”液肥作水稻浸种和孕穗期、灌浆期叶面喷雾。结果表明 :1∶80“天骄”液肥浸种可显著提高水稻秧苗素质 ,增加有效穗 ,增产 3 1 4 % ;喷雾处理的最佳浓度是 1∶30 0 ,最佳时期是孕穗期和灌浆期 ,可显著增加水稻实粒数和千粒重     

TTI交联聚乙烯醇木材胶黏剂的研究

研究在水基中三苯基甲烷-4,4',4"-三异氰酸酯(TTI)交联聚乙烯醇(PVA)所形成的白色乳胶。采用正交试验法探讨聚乙烯醇、催化剂-x、TTI的加入量、反应时间及反应温度对该乳胶性能的影响。合成的单组份环保乳胶适用于木材、纸品等加工业,以及建筑业。