粟类作物稃片植硅体形态研究回顾与展望     

张健平  吕厚远  葛勇  邵孔兰 《第四纪研究》2019,39(1):1-11

中国是粟、黍的起源地,但受植物遗存保存状况及研究方法的限制,对粟类旱作农业起源与驯化的时间、地点、种类、过程等的认识仍然存在不同观点。植硅体分析为准确鉴定粟、黍及其野生祖本和亲缘物种提供了新的途径。本文总结了近几年来针对粟、黍种子稃片植硅体研究取得的新进展,获得以下认识:1)进一步明确了稃片表皮长细胞植硅体的形态特征、大小、数量是鉴定考古文化堆积中粟、黍及其野生祖本和亲缘野生物种的可靠指标;2)通过对比我国北方常见的狗尾草属稃片植硅体,发现了ΩⅢ型仅发育于粟和青狗尾草的稃片中部,且其大小与狗尾草属野生植物差异显著;3)分析和说明了稃片植硅体鉴定流程和方法、重点强调了稃片Ω/η类型的鉴定特征和应用范围,以及植硅体统计量等关键问题;4)讨论了粟类稃片植硅体产量与农作物产量的关系以及植硅体埋藏学问题,最后对深化粟类植硅体形态学研究提出了初步建议。希望通过本文的总结与讨论,能够使植硅体分析方法在粟类作物起源和传播的研究中得到更准确、更广泛的应用。  相似文献   

日本虎杖覆盖对连作的影响——日本西阿瓦陡坡土地农业系统传统耕作评价     

INAGAKI Hidehiro  UNNO Nahoko  SAKAKIBARA Takumi  KUBOTA Sakiko  HASEGAWA Kana 《资源与生态学报(英文版)》2021,12(2):254-259

禾本科物种(例如银草、芦苇)在日本传统的地膜覆盖农业中普遍使用,西阿瓦地区是全球重要的农业遗产系统(GIAHS)所在地。传统上,这里的农民使用银草覆盖农业土壤。但当地农民从长期的经验中了解到,日本虎杖覆盖更适合该地区茄科作物的种植。目前尚不清楚日本虎杖覆盖物为何对茄科作物的种植有益。在本项研究中,我们假设日本虎杖覆盖物可能会有效避免连续种植马铃薯的危害。因为过去每年都会种植两次本地马铃薯,因此,我们调查了日本虎杖覆盖对连续种植马铃薯以及番茄种植后对马铃薯产量的影响。在2018年进行的田间试验中,我们首先在连续马铃薯栽培的土壤和未耕种的土壤中比较了日本虎杖覆盖、银草覆盖和无草覆盖(对照)对马铃薯产量的影响,结果表明日本虎杖覆盖减少了马铃薯产量的降低程度。其次,我们比较了番茄种植后的土壤和未耕种的土壤中的虎杖覆盖和无草覆盖对马铃薯产量的影响,结果再次表明了日本虎杖覆盖减少了马铃薯生长和产量下降的程度。这些发现表明用日本虎杖覆盖有助于避免连续种植马铃薯的风险。  相似文献   

农户行为视角下的乡村生产空间系统运行机制及重构启示   总被引：4，自引：1，他引：3  

王成  马小苏  唐宁  李颢颖  周明茗  何焱洲 《地理科学进展》2018,37(5):636-646

农户行为转变是乡村生产空间系统量变或从量变到质变的重要驱动力,乡村生产空间系统的运行实质上是农户行为作用的外在表现,厘清农户行为可为诠释乡村生产空间系统的运行机制提供平台。本文在剖析农户行为转变与乡村生产空间系统运行响应的理论框架基础上,从农户行为转变和乡村生产空间系统响应入手构建指标体系,建立模糊综合评价量化模型,并以重庆市江津区恒和村作为实证,诠释乡村生产空间系统运行机制。主要研究结论为：不同农户行为对乡村生产空间系统运行的影响程度各异,大体为生产大户>合作社农户>传统农户;不同农户行为对系统运行响应结果的作用差异明显,生产大户行为主要影响乡村生产空间的利用效率,合作社农户行为对提升生产空间系统经济效益作用明显,传统农户行为对生产空间系统环境改善的贡献作用最小。并从经济、社会、空间重构视角提出发展多种形式的适度规模化经营、培育新型农业经营主体和职业农民、合理引导农户技术和资本投入等建议,以实现乡村生产空间系统协调与均衡发展。  相似文献   

Is Larger Scale Better? Evidence from Rice Farming in Jianghan Plain     

WANG Jiayue  XIN Liangjie 《资源与生态学报(英文版)》2018,9(4):352-364

Small-scale household agricultural production has been in conflict with China’s agricultural modernization. In the context of vigorously promoting rural land circulation and moderate scale management nationwide, research on the relationship between farm size and scale efficiency has become increasingly important. In this paper, we use the “DEA-OLS” two stage method to analyze data from 368 surveys of rice farming households in the Jianghan Plain. The scale efficiency of rice farming was calculated, and the relationship between farm size and scale efficiency investigated. The results indicate that (1) the rice farm size is generally small in Jianghan Plain, with an average of 0.77 ha. The average scale efficiency is 0.88, and it is the main factor limiting an increase in comprehensive technical efficiency. Moreover, 88.32% of households are in the stage of increasing returns to scale. (2) There is a stable inverted “U” type relationship between rice farm size and scale efficiency. Considering characteristics of the householder, the household and land quality, the maximum scale efficiency corresponds to a household with 5 ha of rice farm. (3) Among householder characteristics, age has a significant negative influence on scale efficiency, and scale efficiency is lower for a household whose householder is engaged in non-farm work than for one whose householder is devoted to farming. As for land quality, there was a significant positive effect of irrigation on scale efficiency. Among family characteristics, the application of a machine during the seeding process increased scale efficiency by 3.07%. Therefore, we suggest that local government should actively promote rural land circulation, implement a staged-scale management subsidy, and other forms of support for the purchase of agricultural machinery and technical popularization. Increased investment in irrigation improvements and mechanical facilities and encouragement of farmers to enlarge their farm size could improve scale efficiency and farming profit and lead to the development of moderate scale management.  相似文献   

农村居民点耕作距离空间分布特征估测分析   总被引：10，自引：2，他引：8  

赵元  胡月明  张新长  王璐  陈飞香  赵之重 《地理科学》2016,36(5):760-765

基于探索性空间数据分析(ESDA)思想,提出一种耕作距离空间估测方法,定量分析农村居民点耕作距离的分布格局与分异特征。以广东省阳山县为案例,研究表明：① 耕作距离与耕地质量及地形等别存在一定的相关性,耕作半径愈小,地形愈低平的地区,居民点与较优的耕地愈集中;② 耕作距离在空间上呈现不均衡状态,随着距离尺度的增加,耕作距离的变化由低值聚类转为高值聚类状态,表明研究区耕地格局随耕作距离尺度上升变得更加分散;③ 估测方法考虑了农村居民点与耕地之间的关系,可以有效分析耕地与居民点之间的空间分布随耕作距离变化的规律,对农村居民点调整、高标准农田建设等工作的合理开展具有参照和一定指导意义。  相似文献   

干旱环境胁迫下农户适应性研究——基于民勤绿洲地区农户调查数据   总被引：3，自引：1，他引：2  

尹莎  陈佳  吴孔森  杨新军 《地理科学进展》2016,35(5):644-654

适应能力及其评估框架为农户生计研究提供了一个新思路。本文在干旱环境背景下,借鉴农户可持续生计和适应能力相关理论,探讨民勤绿洲地区农户适应能力及适应行为。按照适应能力评估框架,构建农户适应能力评价指标体系,通过问卷和实地调查获取数据,在农户适应行为分类的基础上,测量不同适应类型农户的适应能力,分析影响农户适应类型的因素。结果表明：①从农户的适应行为来看,积极主动的适应行为选择较多,减少消费、参加社会保险等适应行为选择较少;农户适应类型中,综合适应型的比重最大,被动适应型最小。②农户的适应能力方面,各维度整体分布较为均衡,但自然能力和社会能力存在显著分异,而物质能力、金融能力、劳动能力和学习能力较均衡;不同农户适应类型中,综合适应型农户适应能力更稳定,务工主导型和被动适应型的稳定性较差。在适应能力六大维度中,物质能力在六大农户适应类型中所占比重最大,自然能力最小。③家庭物质资产、非农就业比重、社会网络、人均“退还关压”面积、受教育程度等适应能力指标对农户的适应行为选择具有显著影响。  相似文献   

Potential impact of ash eruptions on dairy farms from a study of the effects on a farm in eastern Bay of Plenty,New Zealand; implications for hazard mitigation   总被引：1，自引：1，他引：0  

Thomas M. Wilson  James W. Cole 《Natural Hazards》2007,43(1):103-128

This paper investigates the impact ash fall would have on dairy farming, based on a study of ‘Tulachard’, a dairy farming operation at Rerewhakaaitu, North Island, New Zealand. It includes analysis of the potential effects on the dairy shed and milking machine, electrical supply and distribution, water supply and distribution, tractors and other farm vehicles, farm buildings (haysheds, pump sheds, implement sheds, etc.), milk-tanker access to the farm and critical needs of dairy cows and farm to keep milking. One of the most vulnerable areas identified in the study was the cooling of milk at the milking shed, pending dairy tanker pick-up. The cooling system’s condenser is exposed to the atmosphere and falling ash would make it highly vulnerable. Laboratory testing with wet and dry ash was conducted to determine its resilience to ash ingestion. It was found to perform satisfactorily during dry testing, but during wet testing significant clogging/blocking of the condenser’s radiator occurred, dramatically reducing airflow through the condenser. Specific mitigation recommendations have been developed that include cleaning with compressed air and adapting farm management techniques to lessen usage of the condenser during an ash-fall event. Specific recommendations for management of dairy farm operation are given to mitigate the effects of an ash-fall event.

James W. ColeEmail:

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A sustainability criterion for the exploitation of North Sea cod   总被引：7，自引：5，他引：2  

Cook  R. M. 《ICES Journal of Marine Science》1998,55(6):1061-1070

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Initial Fish-Farm Impact on Meiofaunal Assemblages in Coastal Sediments of the Western Mediterranean   总被引：4，自引：0，他引：4  

A Mazzola  S Mirto  R Danovaro   《Marine pollution bulletin》1999,38(12):420-1133

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Diseases and parasites of Baltic cod (Gadus morhua) from the Mecklenburg Bight to the Estonian coast     

Mellergaard  S.; Lang  T. 《ICES Journal of Marine Science》1999,56(2):164-168

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