两种生测方法对6种杀柑橘木虱药剂毒力测定结果比较

为了寻找杀虫剂对柑橘木虱成虫毒力的测定方法，分别用点滴法和药膜法测定了吡虫啉、联苯菊酯、高效氯氰菊酯、高效氟氯氰菊酯、毒死蜱、丁硫克百威等6种杀虫剂对柑橘木虱成虫的室内毒力。结果表明：用点滴法测出的6种药剂的LC50和LC95高于用药膜法的测定结果，工效只有药膜法的50%，药膜法具有快速、所有药剂都可用的优点，适宜于抗性监测和在丙酮中溶解度低的化合物的毒力测定；点滴法所用药剂不含助剂，具有准确性好，适宜于新的化合物的毒力测定的优点，但具有工效低和在丙酮中溶解度低的原药不能用的缺点。     

人工草地绵羊系统优化研究Ⅳ人工草地划区轮牧罗姆尼怀孕母羊群体采食量研究

人工草地划区轮牧条件下,牧草生长旺季罗姆尼(Romney)怀孕母羊羊群采食量与怀孕日龄间呈显著正相关,回归方程Y=0.003 2X+0.853 7,r=0.949 5;但霜冻到来后采食量与怀孕日龄间呈显著负相关,回归方程Y=-0.007 3X+1.784 1,r=-0.985 1.     

Application of the Soil and Water Assessment Tool (SWAT) to predict the impact of alternative management practices on water quality and quantity

Alternative land management practices such as conservation or no-tillage, contour farming, terraces, and buffer strips are increasingly used to reduce nonpoint source and water pollution resulting from agricultural activities. Models are useful tools to investigate effects of such management practice alternatives on the watershed level. However, there is a lack of knowledge about the sensitivity of such models to parameters used to represent these conservation practices. Knowledge about the sensitivity to these parameters would help models better simulate the effects of land management. Hence, this paper presents in the first step a sensitivity analysis for conservation management parameters (specifically tillage depth, mechanical soil mixing efficiency, biological soil mixing efficiency, curve number, Manning's roughness coefficient for overland flow, USLE support practice factor, and filter strip width) in the Soil and Water Assessment Tool (SWAT). With this analysis we aimed to improve model parameterisation and calibration efficiency. In contrast to less sensitive parameters such as tillage depth and mixing efficiency we parameterised sensitive parameters such as curve number values in detail.In the second step the analysis consisted of varying management practices (conventional tillage, conservation tillage, and no-tillage) for different crops (spring barley, winter barley, and sugar beet) and varying operation dates. Results showed that the model is very sensitive to applied crop rotations and in some cases even to small variations of management practices. But the different settings do not have the same sensitivity. Duration of vegetation period and soil cover over time was most sensitive followed by soil cover characteristics of applied crops.     

Response of Cotton to Irrigation Methods and Nitrogen Fertilization: Yield Components,Water‐Use Efficiency,Nitrogen Uptake,and Recovery

Efficient crop use of nitrogen (N) fertilizer is critical from economic and environmental viewpoints, especially under irrigated conditions. Cotton yield parameters, fiber quality, water‐ and N‐use efficiency responses to N, and irrigation methods in northern Syria were evaluated. Field trials were conducted for two growing seasons on a Chromoxerertic Rhodoxeralf. Treatments consisted of drip fertigation, furrow irrigation, and five different rates of N fertilizer (50, 100, 150, 200, and 250 kg N /ha). Cotton was irrigated when soil moisture in the specified active root depth was 80% of the field capacity as indicated by the neutron probe.

Seed cotton yield was higher than the national average (3,928 kg/ha) by at least 12% as compared to all treatments. Lint properties were not negatively affected by the irrigation method or N rates. Water savings under drip fertigation ranged between 25 and 50% of irrigation water relative to furrow irrigation. Crop water‐use efficiencies of the drip‐fertigated treatments were in most cases 100% higher than those of the corresponding furrow‐irrigated treatments. The highest water demand was during the fruit‐setting growth stage. It was also concluded that under drip fertigation, 100–150 N kg/ha was adequate and comparable with the highest N rates tested under furrow irrigation regarding lint yield, N uptake, and recovery. Based on cotton seed yield and weight of stems, the overall amount of N removed from the field for the drip‐fertigated treatments ranged between 101 and 118kg and 116 and 188 N/ha for 2001 and 2002, respectively. The N removal ranged between 94 and 113 and 111 and 144 kg N/ha for the furrow‐irrigated treatments for 2001 and 2002, respectively.     

Effect of Tillage and Plant Residue Management Practices on Shrinkage of a Vertisol

A study was carried out to determine the effects of different tillage and plant residue management practices on different soil moisture and shrink-swell properties of a Vertisol (very fine, semctitic, thermic, chromic Haploxerert (with less than 1 % slope). The core samples were collected in July (after harvesting of lentil) and in November (after planting of wheat) 1993. The two tillage methods were moldboard (T1) and chisel (T2). The two plant residue incorporation dates were in August (R1) and in October (R2). Results indicated that T2 tends to give higher water holding capacity and available moisture than T1. Immediate incorporation of plant residue (R1) tends to increase the bulk density and to decrease soil specific volume and void ratio when compared to late incorporation treatment (R2). In general, the two tillage treatments tend to decrease moisture availability, shrinkage characteristics, soil specific volume, and void ratio. They also tend to increase the soil shrinkage (subsidence and cracks volume) and bulk density. Chisel plough is recommended in Vertisols, if it is to be used before the rainfall.     

Effect of Tillage System on Soil Strength and Bulk Density of Vertisols

Improving the soil environment for seedling emergence and plant growth is possible using a good tillage system. From March 1993 until June 1994, the effect of tillage system and plant residue incorporation practices on the bulk density and the soil strength of the surface layer of a vertisol (very fine, smectitic, thermic, chromic Haploxerert), on a less than 1 % slope, was investigated. The two tillage methods were moldboard (T1) and chisel (T2). The two plant residue incorporation dates were in August (R1) and in October (R2). Results indicated that R1 gave significantly higher bulk density than R2, while the different tillage treatments had no significant effect. Soil strength was significantly lower under T1 and R2 than under the other treatments.     

玉米根茬图像的分割方法

对保护性耕作留茬覆盖情况下田间玉米根茬图像进行了分割.选取采集图像的彩度信息作为对象,通过对几种常用的自动阈值选取算法的比较,选择了迭代法对田间图像进行分割.实验结果表明:该方法能够有效地将根茬目标与土壤背景分割开来,为下一步检测行茬直线并将其作为导航基准线进行视觉导航的研究提供了基础.     

施肥量对水稻准两优527产量和营养动态的影响

贵州省黔南苗族布依族自治州属于中国西部丘原山地，平均海拔1100m，岩溶地貌发育典型，土壤贫瘠且宜耕作性较差，耕作粗放，作物的产量一直不高。农民为了提高作物的产量，大量施用无机肥料，肥料利用效率逐步降低，而且肥料的大量施用已经引起了严重的环境问题，因此合理运筹肥料是提高肥料利用率、减少污染的重要措施。     

陕西不同地区沙棘叶的营养成分分析

本文对陕西的宜君、黄龙、靖边、吴旗、永寿5地沙棘叶进行了营养分析，发现陕西不同地域的沙棘叶含有较高的粗蛋白、粗脂肪、丰富的氨基酸和维生素及微量元素，其营养价值优于或等于苜蓿草粉及白三叶干草等常规饲料，证明沙棘叶是应该大力推广应用的优良饲料和饲料添加剂。     

开阔型港湾紫菜埕地轮养菲律宾蛤仔的研究

利用开阔型港湾紫菜养殖埕地空闲季节，进行小型试验并指标大面积轮养菲律宾蛤仔，选择含沙星８０％－９０％的沙泥稳定底质，海水比重１．０１６－１．０２２，大潮干露２－４小时，流速８０－１００厘米／秒，饵料丰富的海区，１－２月份播种壳长２．０－２．２厘米的一龄大蛤苗，密度１０００个／米＾２。