气候变化对非洲水资源和农业的影响

尽管非洲是世界上温室气体排放总量或人均排放量最少的地区,但在承受气候变化造成的恶劣影响方面首当其冲。气候变化已经给非洲的水资源、农业、生物多样性、人类健康和国家安全等带来诸多严重影响,粮食生产和水资源一直是非洲长期面临的两大难题,也是深受气候变化影响的两大领域还较欠缺,需要在未来的研究中进一步加强,以探寻减缓气候变化对非洲水资源和农业不利影响的有效途径。本文系统梳理了气候变化对非洲水资源系统和农业生产影响的研究成果和不足,以期为非洲气候变化影响评估工作提供一定参考和借鉴。已有的观测结果表明,气候变化导致非洲许多山脉冰川面积正在大范围缩减、大部分地区降水量有所减少,降雨的年际间分布也更为不稳定,通过水文模型的模拟预测,未来气候变化将进一步影响降水量和非洲部分地区河流的径流量,导致非洲水资源供给压力加大。同样,气候变化也给非洲农业生产带来了巨大的挑战,无论是观测结果分析,还是统计模型和作物模型等对不同气候情景和时间尺度下非洲农业的模拟研究,都显示气候变化对非洲农业以负面影响为主,导致非洲干旱加剧、生长季改变和粮食产量下降,并可能危及非洲的粮食安全。然而,现有研究结果还存在较多不确定性,其主要集中在未来气候情景数据、研究方法、数据的质量和数量等方面。与世界其它地区相比,非洲气候变化影响研究无论是研究的深度和广度都     

甘薯淀粉产量及相关性状的遗传多样性和关联度分析

甘薯[Ipomoea batatas(L.)Lam.]是加工淀粉和燃料乙醇的重要原料,是目前我国最具开发前景的非粮食类新型能源作物。选育高淀粉产量的能源型甘薯新品种是甘薯育种的重要目标。为了获得准确筛选高淀粉产量育种材料的性状指标,提高甘薯高淀粉产量育种效率,缩短育种周期,本研究利用不同甘薯品种(系)的自然变异,根据淀粉产量、不同生长发育阶段的5个主要农艺性状和3个淀粉合成关键酶活性测定结果,利用相似系数和遗传距离矩阵,以类平均法对国内48份不同淀粉产量甘薯种质资源进行了遗传多样性分析,通过关联度分析研究了淀粉产量与不同时期农艺性状、淀粉合成关键酶活性的相关性。结果表明:48份甘薯种质资源材料在不同时期农艺特征差异较大;不同时期农艺性状的聚类结果中,栽后100 d的农艺性状与淀粉产量关联度最大,淀粉产量与该时期的基部分枝数呈极显著负相关(r=0.428),与干率呈极显著正相关(r=0.423),而与最长蔓长、单株结薯数和单株鲜薯重相关性不显著。48份甘薯种质材料在不同时期的酶活聚类结果差异明显。不同时期的甘薯淀粉合成关键酶活性聚类结果中,栽后50 d酶活聚类与淀粉产量聚类结果关联度最大,淀粉产量与该时期测得的ADPG焦磷酸化酶(ADPG-PPase)活性呈负相关关系(r=0.163),与蔗糖合成酶(SS)活性(r=0.101)、蔗糖磷酸合成酶(SPS)活性(r=0.016)呈正相关,但相关性均未达到显著水平。加之淀粉合成关键酶活性测定步骤繁琐,不适宜作为甘薯高淀粉产量育种早期选择的生理指标。在高淀粉产量育种材料筛选时可于栽后100 d对农艺性状进行综合考察,重点考虑干率较高及分枝数较少的品系。本研究可为甘薯高淀粉产量育种提供一定的理论依据。     

农业院校图书馆网站建设的探讨

对我国25所农业高校图书馆网站的主页元素、内容元素和编程技术等进行比较,分析了存在的缺陷和问题。针对农业高校图书馆网站建设的原则和内容,提出了网站建设的目标定位等原则,建议优化主页设计、丰富信息资源、规范学科导航、提升服务功能、适度设置链接、适时维护更新和应用现代技术手段,并对主页与标识、栏目与层次等提出了具体的建议。     

Biochar derived from dairy cattle carcasses as an alternative source of phosphorus and amendment for soil acidity

Two pot experiments were conducted to evaluate biochar derived from dead dairy cattle as a mineral fertilizer, especially phosphorus (P) fertilizer, and to clarify the effect of particle size of biochar on plant growth (Zea mays L.) and P uptake. To produce the biochar, body parts of dead cattle were placed in a charring chamber and allowed to char at 450°C for 4 h. The biochar was of high pH and rich in major plant nutrients, especially P. Application of fine biochar (< 1 mm) increased P uptake by the corn plants grown in soil of low available P status. As a result, plant growth was improved following biochar application and dry matter production was also increased. The effect of the biochar application on the P uptake and plant growth was promoted by the application of mineral nitrogen (N) fertilizer. Soil analysis after harvest indicated that the biochar application increased soil pH, available P and exchangeable calcium (Ca) and magnesium (Mg) compared with the soil before seeding, while soil available N and exchangeable potassium (K) were considerably decreased. The decrease in the soil available N was incomprehensible, because the result of the mass balance given by the difference between input as the applied N from the biochar and fertilizer N and output as the N uptake by the plants was positive. We observed a similar result in the mass balance of K to the case of N. The medium (2–4 mm) and coarse (> 4 mm) grade biochar did not significantly affect plant growth, because P uptake was not, or was only slightly, increased by the application of these biochars. Dissolution of P from the coarser biochars was probably slower than that of the fine biochar. The lower dissolution of P from the medium and coarse biochars was supported by the lower P absorption efficiency of these biochars compared with that of the fine biochar and superphosphate. The effect of fine biochar on plant growth and P uptake was similar to that of superphosphate. We can therefore conclude that fine biochar derived from cattle carcasses is an effective source of P fertilizer and amendment for soil acidity. The N and K contents in the biochar, although relatively high, cannot be relied upon as a mineral fertilizer. Further studies are needed to assess whether the N and K contents of the biochar indicate it can be regarded as a useful fertilizer.     

江苏沿海耕地资源量空间分布态势评价

首先采用农用地分等中自然质量分值的计算方法对江苏沿海耕地自然质量进行测算,然后在此基础上结合各乡镇耕地面积和人口数量计算人均耕地量,对江苏沿海地区耕地资源量的空间分布态势进行评价。结果表明:研究区北部、中西部和南部除少数地区外耕地质量总体较好,中东部耕地质量较差;耕地质量优良的地区人均耕地量水平较低,耕地质量较差的地区人均耕地量水平反而较高。根据评价结果,从提高土地整体利用效率、合理占用耕地、合理开发土地后备资源、污染排放源头控制与生产过程中治理相结合等几个方面提出了沿海地区耕地资源可持续利用的有效途径。     

Genetic diversity in Cynara cardunculus revealed by AFLP markers: comparison between cultivars and wild types from Sicily*

Genetic diversity in 49 plants of 16 accessions representing one wild and two cultivated taxa of Cynara cardunculus L. (wild cardoon, cultivated cardoon and globe artichoke) was investigated using amplified fragment length polymorphic (AFLP) analysis. Four pairs of primers identified a total of 264 scorable loci, 196 of which were polymorphic. The number of markers scored per primer combination ranged from 41 to 107, with an average of 66 markers per primer combination. All the primer combinations detected polymorphism. The data were used for cluster analysis and AMOVA. The clusters obtained are in agreement with the current botanical classification and the differences among the taxa were substantial. The eco‐geographical groups within wild cardoon are clearly separated in relative subclusters, and reflect the geography of the collection areas. The six clones of the four cultivated artichoke varieties were clearly separated into four subclusters, corresponding to the current classification which is based on morphological traits. The results obtained may have a direct and important bearing on plant genetic resource conservation and management and on breeding.     

论新农村建设时期的农村人力资源开发

农村人力资源开发在建设社会主义新农村中起着战略性、基础性和决定性的作用。笔者结合建设新农村的具体要求,通过分析农村人力资源开发现状中存在的问题,指出了在建设新农村时期开发农村人力资源,必须要处理好自然资源开发与人力资源开发的关系,要加强农村保障体制和组织化程度建设,要重视农村教育的战略地位、农村劳动力技能培训的主导地位、建设学习型社会的根本地位,这样才能培育新农民,全面提高农民素质,为建设社会主义新农村提供人力支持和智力保障。     

高校水资源情况调查分析

为推进节水型校园的建设,以成都信息工程学院为例对高校水资源利用情况进行调查,根据调查结果剖析了高校水资源不合理使用原因,并结合高校现有水资源节约利用规划提出了高校节水的合理建议。结果表明高校水资源利用存在较大隐患,用水管理模式不完善等是导致高校水资源不合理利用的原因,并相应提出了改善用水管理模式等合理利用水资源和提高水资源综合利用率的措施。     

引进前苏联陆地棉种质资源主要农艺及经济性状鉴定研究

针对国内棉花生产发展的需要,在石家庄地区自然条件下,我们对引进前苏联的１２９份和国内的７２份陆地棉种质资源的农艺性状、产量及产量因子和纤维品质等性状进行了系统的同步鉴定研究,结果表明：引进材料同国内材料相比,生育期相差不大,引进材料具有株高较矮、果枝节位较低,铃重较高,纤维较整齐,强度高,细度好的特点,而且,在果枝数、叶枝数、单株铃数、单铃重、衣分、子指、纤维整齐度、纤维伸长率等性状的变异潜力和变化幅度均大于国内种质资源。通过系统同步鉴定,筛选出早熟、矮秆、高衣分、高子指、长纤维、高强度和细度好等不同特性的优异材料４４份,改善了我国棉花种质资源缺乏的现状。     

基于人粮关系的土地资源承载力研究

随着我国人口的不断增长,土地的承载能力和粮食安全问题越来越受到广泛的关注。本文从人粮关系角度出发,基于可持续发展基本理论,运用土地资源承载力(LCC)模型,以我国农业和人口大省河北省为例,对河北省土地资源承载能力进行了计算,并以土地资源承载指数(LCCI)为指标,以县级行政地区为单元划分了土地资源的人口承载力等级。结果表明,河北省68.71%的县域为粮食盈余区,17.01%的县域为人粮平衡区,其余14.28%的县域为粮食超载区。在此基础上对河北省具有代表性的县域单元进行了讨论,并提出了提高土地资源人口承载力的对策。