农业高效用水理论研究综述

农业高效用水包括节水灌溉和旱作农业,其核心是提高自然降水和灌溉水的利用效率和效益．农田蒸散的测定方法各有利弊．FAO先后建议用Penman修正式和Penman-Monteith公式计算参考作物蒸散量．Jensen乘法模型和Blank加法模型在作物水分生产函数研究中得到广泛应用．土壤适宜含水量和土壤干旱下限指标的最新研究成果,为低定额的农业供水提供了土壤物理学的重要依据．水分亏缺对与产量形成相关的各个生理过程影响的先后顺序为细胞扩张＞气孔运动＞蒸腾运动＞光合作用＞物质运输．不很严重的干旱反而对物质运输有促进作用．农田灌溉研究已由传统的充分灌溉,转向非充分灌溉、调亏灌溉和控制性分根交替灌溉．未来农业高效用水理论将在界面、土壤水动力学、生物节水、缺水逆境等方面深入开展研究。     

Early seedling growth of pine (Pinus densiflora) and oaks (Quercus serrata,Q. mongolica,Q. variabilis) in response to light intensity and soil moisture

In climatic chambers seed germination and seedling growth of Pinus densiflora Sieb. et Zucc., Quercus serrata Thunb., Quercus mongolica Fisch. ex Turcz. and Quercus variablilis Bl. were investigated as functions of light intensity and soil moisture. In Korea these tree species occur widely and form mixed forests with different distributions. Species clearly differed in the pattern of germination and early seedling growth between light and soil treatments. The germination of pine did not differ between the experimental treatments until the breaking of the primary buds. After that, light intensity was the deciding factor for further development. In the most moist treatment (approx. field capacity) growth of the pine seedlings was strongly inhibited. For the three oak species, differences between experimental treatments first occurred after complete formation of primary leaves. Seed development strongly correlated with the weight of the acorn. The large seeded Q. variabilis (acorns with mean weight of 4.7 g) developed faster and reached larger dimensions towards the end of the experiment than Q. mongolica (2.8 g per acorn) and Q. serrata (0.9 g per acorn). Regarding height and biomass growth, the oak species showed a higher shade tolerance than pine. The proleptic shoot growth was clearly influenced by the light intensity. Root formation was favoured by a high exposure to light. In case of the oak species reduction of soil moisture increased the length of primary roots and the number of secondary roots.     

Microhabitat use by the rainbowfish <Emphasis Type="Italic">Melanotaenia duboulayi</Emphasis> in a subtropical Australian stream

Microhabitat use and feeding behavior of the rainbowfish Melanotaenia duboulayi (Castelnau) were investigated in a slow-flowing stream adjacent to riparian forest in south-eastern Queensland, Australia. Fish were more abundant in vegetated areas, but did not enter dense Vallisneria beds, where predators were observed. In sunny conditions shoals of juveniles occurred near the water surface feeding floating material on the surface, but larger fish tended to occur at the bottom near submerged vegetation, often utilizing the overhanging aquatic plant community as a refuge and food source. In the middle of the day, juveniles and small fish seemed to show behavioral thermoregulation at the surface in the warmest site. Under cloudy conditions, however, fish of all sizes preferred deeper water. The present study suggests that in still and sunny pools thermal change caused by sunlight influences the microhabitat choice of small fish. A field experiment using a kingfisher model implies that fish swimming at the surface could escape from aerial predators in sunlit conditions by responding to moving shadows, but could not do so under cloudy conditions. Electronic Publication     

An investigation into the relationship between water beetle (Coleoptera) distribution and land cover in Scotland and northeast England

Aims To determine the relationship between satellite‐derived land cover data and distribution patterns of water beetle species pools. Location A total of 687 British national grid 10 km squares in Scotland and 588 1 km grid squares in 99 10 km grid squares in northeast England. Methods Multivariate classification and constrained ordination analyses were used with water beetle species and land cover data. Results The major variation in both the Scotland and northeast England 10 km species pools was from squares with upland acid water habitats to squares with lowland fens and ponds whilst for the 1 km northeast England data it was from squares dominated by fast‐flowing streams and rivers to those with fens and ponds. The secondary variations in the 10 and 1 km analyses were the primary ones juxtaposed. Constrained ordination of the Scottish 10 km data showed upland land cover types to be most influential in determining species pool distribution whilst lowland covers were more important with both the 10 and 1 km northeast England pools. The three analyses showed that coastal cover had a relatively high influence on species pool distribution but no species pool group was dominated by coastal species. Main conclusions There were strong relationships between water beetle species pool distributions and the satellite‐derived land cover types dominating upland and lowland areas. The major variation in the northeast England species pool data differed at the two scales analysed. Results indicated that there is considerable potential for the synthesis of water beetle distribution and land cover data for use in environmental and conservation monitoring at both the regional and national scales.     

Strategies for effective mosquito control in constructed treatment wetlands

Constructed wetlands hold considerable promise for providing water quality and wildlife habitat benefits. At the same time, constructed wetlands have been described as “mosquito-friendly habitats” and may raise potential conflicts with neighboring human populations. Conflicts arise because some design features, such as shallow water and emergent vegetation that are essential for optimizing water quality polishing, can result in undesirable increases in mosquito production. The attraction of large numbers of birds to constructed wetlands could also increase the risk of transmission of mosquito-borne viral infections to humans in the vicinity of the wetland. The potential for conflict is typically highest in arid regions where natural mosquito populations have limited abundance and are found near newly urbanizing areas.The creation of wildlife habitat is a significant goal of many treatment wetlands. Humans are also welcome in many treatment wetlands for recreational and educational activities. Risks of disease transmission to humans and livestock as well as the inconvenience of mosquitoes as pests must be offset by the economic savings of inexpensive water quality enhancement and the resulting reduction in pollution that also poses a risk to society’s health and well-being. Ecological risks associated with the use of mosquito control chemicals must be offset by the increased habitat benefits provided by these constructed wetlands. The right balance between these competing goals can be recognized by the design that provides the greatest net environmental and societal benefit. This paper describes these tradeoffs between mosquito control and the constructed wetland technology and provides a synthesis of information that can be used to optimize the benefits of these wetland systems. Basic research is recommended to better define the cost-effectiveness of the various design and management options.     

重庆国家重点保护野生植物的分布与水热关系的初步研究

通过对重庆国家重点保护野生植物的分布与水热关系的研究,确定了这些植物种分布的水热幅度,并利用温暖指数(WI)、寒冷指数(CI)和湿润指数(HI)对这些植物种进行聚合分类,结果可将这些植物种分为5个水热分布类群：Ⅰ．高温湿润型,Ⅱ．高中温湿润型,Ⅲ．中温湿润型,Ⅳ．低中温湿润型和Ⅴ．低温湿润型。另外,研究还表明了重庆地区的水热条件较好,适合这些重点保护野生植物的生长发育,因此,水热条件的现状不是濒危植物种濒危的主要原因,而人为破坏是其濒危的相当重要的因素。     

发菜(Nostoc flagelliforme)培养条件的研究

研究了光照强度、日供水次数、CO2浓度和培养基成分对发菜生长的影响。结果显示,中度光强(114μmol.m-2.s-1)下发菜生长最快;发菜的生长基本同供水次数成正相关系;CO2浓度的升高并没有显著促进发菜生长,低光条件下(57μmol.m-2.s-1),高浓度的CO2(2800μL/L)抑制了发菜的生长;用BG11培养的发菜生物量的增长显著高于用BG110培养的;BG11培养基中K+和CO32-的缺失并没有显著影响发菜的生长。     

适应是进化生物学研究的永恒主题

适应是什么?是一个过程(Process),一种状态(State),或是特指某个体的特征(Trait),可指生物现象或是非生物现象。在Rose&Lauder的《Adaptation》一书里,多位在适应进化研究领域里造诣很深的科学家对适应的概念、发展历史、研究适应的方法论和丰富多样的适应过程作了详细的描述。该书共分3部分,14章。     

氮肥和水分条件对长喙田菁生长、结瘤和固氮的影响

 盆栽试验研究了长喙田菁(Sesbania rostrata) 茎瘤固氮根瘤菌（Azorhizobium caulinodans）共生体系在不同水分和无机氮肥条件下的生长、结瘤和氮积累。水分处理为: 不浸水、浅浸水(土壤水分为田间持水量)和深浸水, 氮肥处理分别为每千克土施加无机氮肥10 mg、20 mg和40 mg。结果表明,水分条件对共生体系有较大影响, 浸水环境虽然抑制了根瘤的形成, 却促进了茎瘤的结瘤作用和长喙田菁根系的生长, 田间持水量状态下共生体系能获得最大的生物量和氮累积量; 无机氮肥对共生体系的影响受水分供应的影响较大,实验氮肥施用浓度范围内,长喙田菁的结瘤作用对复合态氮无负敏感反应,明显有别于一般根瘤体系的复合态氮反应。