宁夏灌区玉米径粗与气温的关系

通过对玉米径粗及影响径粗的各生育阶段气温的相关性分析，研究宁夏灌区气温条件对玉米径粗的影响．结果表明，气温是玉米生殖生长期的关键因素．其中，在玉米生殖生长期乃至全生育期中，平均最高气温、平均日较差对玉米花穗分化及干物质的积累影响都较明显．在田间试验观测取值范围内，玉米径随气温的升高而逐渐增粗，产量也随之增加．但在拔节一抽雄期、乳熟一成熟期，玉米径却随≥10℃平均积温和平均日较差的增加而逐渐变细，产量下降。     

A flexible approach to managing variability in grain yield and nitrate leaching at within-field to farm scales

We up-scaled the APSIM simulation model of crop growth, water and nitrogen dynamics to interpret and respond to spatial and temporal variations in soil, season and crop performance and improve yield and decrease nitrate leaching. Grain yields, drainage below the maximum root depth and nitrate leaching are strongly governed by interaction of plant available soil water storage capacity (PAWC), seasonal rainfall and nitrogen supply in the water-limited Mediterranean-type environment of Western Australia (WA). APSIM simulates the interaction of these key system parameters and the robustness of its simulations has been rigorously tested with the results of several field experiments covering a range of soil types and seasonal conditions in WA. We used yield maps, soil and weather data for farms at two locations in WA to determine spatial and temporal patterns of grain yield, drainage below the maximum root depth and nitrate leaching under a range of weather, soil and nitrogen management scenarios. On one farm, we up-scaled APSIM simulations across the whole farm using local weather and fertiliser use data and the average PAWC values of soil type polygons. On a 70 ha field on another farm, we used a linear regression of apparent soil electrical conductivity (EC_a) measured by EM38 against PAWC to transform an EC_a map of the field into a high resolution (5 m grid) PAWC map. We then used regressions of simulated yields, drainage below the maximum root depth and nitrate leaching on PAWC to upscale the APSIM simulations for a range of weather and fertiliser management scenarios. This continuous mapping approach overcame the weakness of the soil polygons approach, which assumed uniformity in soil properties and processes within soil type polygons. It identified areas at greatest financial and environmental risks across the field, which required focused management and simulated their response to management interventions. Splitting nitrogen applications increased simulated wheat yields at all sites across the field and decreased nitrate leaching particularly where the water storage capacity of the soil was small. Low water storage capacity resulted in both low wheat yields and large leaching loss. Another management option to decrease leaching may be to grow perennial vegetation that uses more water and loses less by drainage.Paper from the 5th European Conference on Precision Agriculture (5ECPA), Uppsala, Sweden, 2005     

Effects of Root-Growing Space on Its Absorbing Characteristics

Influences of root-growing space of maize upon root physiological characteristics, nutrient uptake and crop yields were studied under conditions with and without supply of water and N. Results showed that limitation of the root-growing space greatly affected root growth, decreased total root-absorbing area and TTC-reductive amounts. However, it obviously increased the root active-absorbing area, specific absorbing area (absorbing area per gram root weight) and specific active-absorbing area (actively absorbing area per gram root weight) in addition to promoting the TTC-reductive intensity. This clearly showed that plants were not passively tolerant to stress, but actively regulated their physiological metabolic processes, and strengthened their absorbing ability to increase water and nutrient uptake so that root injury by the environmental stress could be reduced. Supply of water and N stimulated root growth, increased root-absorbing area and activity, promoted nutrient uptake, and therefore increased crop yield and decreased the detrimental effects resulting from the limitation of roots-growing space.     

长白山野生植物资源开发利用的思考

通过对长白山野生植物资源的调查，得知该区野生植物资源丰富，物种繁多，是我国一座天然的立体资源宝库，是发展山区经济的重要资源．合理开发这些资源是谋求经济持续稳定，协调发展的必要途径．文章根据野生植物资源的种类、分布及开发现状，提出了该区资源开发过程中存在的问题及原因，解决这些问题的对策和今后合理开发的一些建议．     

浅谈“入世”后县域工业经济的发展问题

久世”后，发展县域工业经济，必须遵循WTO体制规则，遵循市场经济规律，抓住四个关键性措施:一是提高政府的服务质景;_是依托资源，瞄准市场，调整工业布局;三是优化人才环境;四是优化融资环境。     

中国期刊全文数据库(CJFD)中"三农"问题的文献计量分析

本文采用文献计量学的方法分析了1993～2003年,有关"三农"问题的文献量动态变化,著者情况和热点等问题。     

铁岭地区不同洋葱品种生长发育特性与环境条件关系研究

[目的]探讨不同洋葱品种的差别,筛选出适宜铁岭地区栽培的洋葱品种。[方法]以熊岳圆葱为对照,采用随机区组设计,3次重复。[结果]供试9个品种都是长日照类型,鳞茎膨大均需要15 h以上的日照时数。在供试的品种中,生育期比较长,鳞茎重和小区产量都比较高的品种是太阳06-1和太阳06-3。生育期属于中等长度的,鳞茎重和小区产量比较高的品种是太阳06-9和太阳06-13。生育期较短,鳞茎重和小区产量比较高的品种是富士-95。[结论]在供试的9个品种中,适宜铁岭地区栽培的品种是太阳06-1、太阳06-3、太阳06-9和太阳06-13、富士-95。     

黑龙江垦区水稻害虫种类调查

通过田间调查，共查出黑龙江垦区为害水稻的害虫有44种。其中，前人有报道的有29种，新发现15种。     

江西省及南方集体林区森林资源比较

江西省是我国重要的林业大省之一 在南方10省中,江西省森林资源面积以及森林覆盖率排第2位,单位面积蓄积量、年均林分生长率、林种结构、树种结构、林龄结构及天然林资源质量均处于相对弱势地位 江西省森林资源管理的重点应当是质量管理,通过调整树种和林分结构,改造低产人工林,建设工业原料林基地,带动江西省营林产业化水平的全面提高     

当前大别山区农村存在的“五难”问题及其对策

本文揭示了当前大别山区农村存在的主要难题，分析了存在问题的原因，并提出了解决问题的对策和建议