保护性耕作技术推广和应用浅析

涡阳县地处淮北平原中部,涡河横穿县境,地势平坦,士层深厚。土地面积2109km2,耕地面积13．2万hm2,是安徽的一个农业大县。主要种植的农作物是小麦、玉米。2010年该县被农业部定为保护性耕作示范县,由于措施得力,     

国内访花传粉昆虫研究的文献计量学分析

全面了解中国访花传粉昆虫领域的研究现状,客观地进行分析,为访花传粉昆虫科研工作者与决策者提供数据参考。以《中国知网》的《中国期刊全文数据库》为数据源,运用文献计量学的原理和方法,对访花传粉昆虫研究的年代、作者、机构、载文期刊、研究内容及基金资助进行分析。结果表明,检索出1980—2013年国内访花传粉昆虫研究专题256名作者在133种刊物上发表的308篇文献,揭示了30多年间国内该领域研究的动态变化和基本态势。中国访花传粉昆虫研究发文量逐年增加;机构分布广,高产机构较少;研究者众多,高产活跃作者队伍不够强大,核心作者数量及所发论文质量不是很高;研究内容广泛丰富,不同研究方向成果数量不均衡。     

南洞庭湖15种野生蚌类遗传多样性分析

采用RAPD技术,选用11条有效随机引物研究了南洞庭湖15种野生蚌(圆顶珠蚌、尖锄蚌、圆头楔蚌、鱼尾楔蚌、巨首楔蚌、射线裂脊蚌、球形无齿蚌、勇士尖嵴蚌、扭蚌、杜氏珠蚌、背瘤丽蚌、短褶矛蚌、三巨瘤丽蚌、环带丽蚌、蚶形无齿蚌)之间的遗传多样性,得到RAPD-DNA扩增条带1 775条,片段长度500～1 500 bp,平均每条引物扩增出43.5条带,这些条带构成了南洞庭湖15种野生蚌的遗传多样性图谱.分析表明,属间的遗传距离以裂脊蚌属和尖嵴蚌属间最近,为0.485 7,丽蚌属与其他属间的遗传距离最远,为0.729 2;种间的遗传距离以圆头楔蚌和巨首楔蚌间最小,为0.333 3,背瘤丽蚌与三巨瘤丽蚌及环带丽蚌的遗传距离最大,为0.678 2.从种属关系归属来看,丽蚌属和尖锄蚌属归属于小方蚌亚科;无齿蚌属归属于无齿蚌亚科;矛蚌属、扭蚌属、裂脊蚌属、尖嵴蚌属、楔蚌属和珠蚌属同归属于珠蚌亚科.     

干旱区平原水库防蒸发浮板的力学

针对干旱区平原水库无效蒸发损失严重这一特点，提出用轻质板覆盖部分库区水面以减少无效蒸发，提高水库的有效利用率。为实现这一目标，在合理假设的基础上，本文应用波浪理论、材料力学、弹塑性力学等基础理论建立轻质浮板的计算模型，从而确定单块浮板的物理和几何参数，为水库防蒸发节水工程实施提供计算依据。     

走进战国最酷校园

气吞云梦泽,波撼岳阳城。我曾到过云梦泽——这三个字是洞庭湖更富有诗意的别名。因此,在去云梦山之前,我绞尽脑汁,思考这雅号相同的一山一泽之间,到底有什么亲戚关系。我想,如果有的话,那也一定是远房,它们隔得实在不近,云梦泽在湖南北部的岳阳境内,而云梦山在河南北部的淇县境内。两省中间,还插着一个诺大的湖北省。     

Progress and Yield Bottleneck of Aerobic Rice in the North China Plain: A Case Study of Varieties Handao 297 and Handao 502

Aerobic rice has been considered a promising rice cultivation system as water scarcity is increasing in the world. This article summarizes the advances in aerobic rice management researches in the North China Plain, focusing on yield formation and its bottleneck. High-yielding and good-quality aerobic rice varieties adapted to aerobic soil conditions have been released officially and adopted by farmers in North China. The varieties Handao 502 and Handao 297 have been recognized as the most promising varieties reaching a yield level ranging 3.5-5.0 t ha-1 with 450-650 mm water input. Compared with lowland rice, water input in aerobic rice was more than 50% lower, and water productivity was 60% higher. Researches on responses of rice cultivars to nitrate nitrogen （N） and ammonium N supplied at early growth stages provided the first evidence for a preference of aerobic rice HD297 for nitrate N supply, compared with the lowland rice variety. Zinc uptake studies demonstrated that introduction of aerobic rice system on calcareous soils may increase zinc deficiency problems. Sink size was identified as the limitation of aerobic rice yield, because its spikelet number m-2 was too low （20000-24 000） compared with the lowland rice. For future research, more attention is suggested to be paid to yield formation focusing on effects of water regimes on tiller dynamics. Understanding of nutrient uptake and response to fertilization effects are also urgently required to establish optimized crop management technology. Additionally, alternative cropping systems based on aerobic rice should be established, and key sustainability and environmental impact issues in the systems need to be identified.     

海南茶产业发展概况

海南地处中国最南部,海南岛的地势四周低平,中间高耸,以五指山、鹦歌岭为隆起核心,向外围逐级下降.山地、丘陵、台地、平原构成环形层状地貌,梯级结构明显.     

圈养湖羊养殖技术要点

平原地区农民如将羊只圈养,可解决日益突出的农牧矛盾,又可开辟饲草资源,使农作物秸秆综合利用,减少因焚烧秸秆造成的环境污染,与