中华微刺盲蝽对茄二十八星瓢虫卵的捕食功能反应

在室内进行了中华微刺盲蝽4龄若虫、5龄若虫和成虫对茄二十八星瓢虫卵的捕食功能反应试验。采用Michaelis-Menten-Ⅱ功能反应模型进行拟合,并利用捕食潜能A、猎物半饱和密度F两个参数评价中华微刺盲蝽对茄二十八星瓢虫卵密度的功能反应。结果表明,中华微刺盲蝽4、5龄若虫和成虫对茄二十八星瓢虫卵的捕食潜能分别为161.290 3、78.740 2头/d和76.923 1头/d,猎物半饱和密度分别为155.612 9、87.007 9头和70.292 3头。本研究表明,中华微刺盲蝽4、5龄若虫和成虫对茄二十八星瓢虫卵潜在的捕食量大,控制作用强。     

Determining the longer term decline in plant‐available soil phosphorus from short‐term measured values

Once phosphorus (P) applications stop, it is important to know how long it will take for plant‐available P in soil to decline to a particular level for soils with a history of intensive management. The rate of decline in the absence of applied P can be expressed as a half‐life, that is the time in years for it to halve relative to the lowest level measured in the soil. This knowledge is essential when planning long‐term policies for managing the P status of soils. It is important to farmers who wish to optimize applications of P fertilizers and make better use of accumulated P residues to ensure that plant‐available P does not fall below the critical level for the soil and crop because of the risk of losing yield and the inefficient use of other inputs, especially N fertilizer. Lower levels of plant‐available P are also desirable for environmental and ecological reasons. Allowing plant‐available P to decline to the critical level from unnecessarily high concentrations will reduce the risk from P on eroded soil causing adverse effects of eutrophication in surface water. Low levels of plant‐available P are usually considered necessary for establishing species‐rich grassland. A method for determining the longer term decline in plant‐available soil P from short‐term measured values is presented.     

Acute and Chronic Effects of Ammonia on Juvenile Cuttlefish,Sepia pharaonis

The aim of this study was to provide a reference value for the safe regulation and control of ammonia nitrogen in the aquaculture of Sepia pharaonis. The effects of acute and chronic toxicity of ammonia on the cuttlefish, S. pharaonis, were tested experimentally using juvenile S. pharaonis. The results showed that the half‐lethal concentration (LC₅₀ ) values of ammonia nitrogen in juvenile S. pharaonis with a body weight of 6.52 ± 0. 23 g at 24, 48, 72, and 96 h were 31.72, 25.77, 23.33, and 18.33 mg/L, respectively, and the corresponding un‐ionized ammonia nitrogen (UIA‐N) concentrations were 1.66, 1.35, 1.22, and 0.96 mg/L, respectively. Compared with the control, the survival rate, specific growth rate, and feed intake of juvenile S. pharaonis declined significantly, and the feed conversion ratio and hepatosomatic index increased significantly at 56 d after exposure to >1 mg/L ammonia nitrogen. Juvenile S. pharaonis should be maintained at a concentration of ammonia nitrogen of no more than 1 mg/L (UIA‐N is 0.056 mg/L) in culture, and removing harmful nitrogenous wastes from the seawater is critical in maintaining cuttlefish culture.     

黑龙江省半湿润区玉米高密度超高产综合技术研究初报

研究了玉米高密度压力下的品种筛选、合理密度、田间种植方式、配方施肥方案.结果表明,玉米新品种江203、龙单26、吉单27、东农250、吉高2、龙单25适合该区种植,且江203、龙单25、龙单26分别在20 cm、25 cm、30 cm密度水平下产量最高;所选择的5种田间种植方式中以2比空模式产量最高,产量为827.08 kg/667m2;配方施肥也达到了预期效果.     

棉花种子水分测定前处理方法的研究

本试验选用高、中、低三种水分棉花种子、五种处理方法,进行棉花种子含水量的测定。结果表明:“对切法”与国家标准《农作物种子检验规程》的“切片法”相比,在高、中含水量情况下测值差异不显著,且提高工效6倍以上;整粒、夹玻、粉碎等处理测定结果与“切片法”相比,差异达极显著,测值偏低。“对切法”准确、快速、简便,是测定棉花种子水分较好的方法,在当前科研、生产中具有实用价值。     

毒力测定的统计分析方法研究

在机率值法和新机率值法的基础上,提出了基于Logistic回归的2种方法,并对各方法的异同进行了比较。结果表明,Logistic回归法计算简单,分析的准确度和机率值法一致。     

Application of analytic hierarchy process for the selection of cotton fibers

In many engineering applications, the final decision is based on the evaluation of a number of alternatives in terms of a number of criteria. This problem may become very intricate when the selection criteria are expressed in terms of different units or the pertinent data are difficult to be quantified. The Analytic Hierarchy Process (AHP) is an effective way in dealing with such kind of complicated problems. Cotton fiber is selected or graded, in the spinning industries, based on several quality criteria. However, the existing selection or grading method based on Fiber quality Index (FqI) is rather crude and ambiguous. This paper presents a novel approach of cotton fiber selection using the AHP methodology of Multi Criteria Decision Making.     

安徽省河蟹人工半咸水育苗技术分析

在枞阳蟹苗场进行河蟹人工半咸水育苗,选购♀蟹3 500只,蟹1 900只,培育获优质抱卵蟹1 605只,占总♀蟹数的45.86%.盐度为1.6%～2.3%,水温控制在20～24℃,产蟹苗91.5 kg.     

马尾松速生、优质及高产脂半同胞家系综合选择的研究

以15年生的半同胞家系马尾松子代林材料进行相关分析，结果表明，马尾松树高、胸径、产脂力、木材基本密度和管胞长度各性状之间，除产脂力与管胞长度的遗传相关呈负相关（rg=-0.1582)外，其他均表现为正相关。按不同的定向选择目标，对马尾松半同胞家系5个主要经济性状进行无约束综合指数选择分析，结果有24号（信珠1）和3号（平台8）两个家系表现最为突出，同时筛选出若干马尾松半同胞家系供不同生产目的的定向培育推广使用。     

拉萨地区油菜白锈病发生发展的农业气象条件分析

对拉萨１９８８－１９９０年油菜白锈病和同期的气象要素进行了相关分析，６－７月平均气温高，夜间温度大，日较差小，阴雨寡照和空气湿度大，有利于白锈病的发生发展；提高地表温度，可减轻白锈病的发生发展。