作物种植模式对土壤微生物和农田有害生物的影响

土壤是联系地上和地下生态系统的纽带,土壤微生物在土壤养分循环和作物吸收中起关键作用,被称为土壤质量的指标。土壤微生物通过分解土壤有机物,促进养分循环利用,并调控植物生长发育,随着现代农业种植结构的变化,特别是种植制度的改变,地上植物种类和生长状况常常影响土壤中微生物的群落结构和多样性,调控着作物生长发育,农田有害生物的发生,而影响农作物生产。综述了现代农业中几种主要种植模式,如轮作、连作和覆盖等对土壤微生物群落结构及与农作物有害生物的影响,强调科学合理选择种植模式的重要性,最后,讨论了这些种植模式有待深入研究的一些关键问题。     

生物炭基肥对马铃薯田土壤脲酶活性和产量的影响

为明确生物炭基肥在马铃薯生产上的应用效果,以马铃薯品种中薯3号为材料,采用随机区组设计,研究大田条件下,0（CK₀）、300（T₁）、600（T₂）、900（T₃）、1200（T₄）kg/hm²生物炭基肥及与之等量N、P、K化肥（分别为CK₁、CK₂、CK₃、CK₄）对马铃薯田土壤脲酶活性和产量的影响。结果表明,在马铃薯苗期,土壤脲酶活性表现为CK₄>T₄>CK₃>T₃>CK₂>T₂>CK₁>T₁>CK₀;在块茎增长期和成熟收获期,土壤脲酶活性表现为T₄>CK₄>T₃>CK₃>T₂>CK₂>T₁>CK₁>CK₀。马铃薯不同生育时期土壤脲酶活性表现为块茎增长期>成熟收获期>苗期。不同土层脲酶活性表现为0~10cm>10~20cm>20~40cm。马铃薯产量为T₃>T₄>CK₃>T₂>CK₄>T₁>CK₂>CK₁>CK₀。马铃薯产量与各土层脲酶活性均呈正相关,且在块茎增长期和成熟收获期相关性达到极显著水平。生物炭基肥施用量为900kg/hm²时马铃薯产量最高,是适合浙江地区马铃薯种植的推荐施肥量。     

Growth and yield of oleic sunflower (Helianthus annuus L.) under drip irrigation in very strongly saline soils

A four-year trial was set up to test the feasibility of growing oleic sunflower in a very strongly saline wasteland with drip irrigation in the Ningxia plain of Northwest China. The soil salinity expressed as electrical conductivity of the saturation paste extract (EC _e ) was around 28 dS/m, and soil nutrient was deficient in the upper 120 cm depth. The experiment included five soil matric potential (SMP) treatments, with the SMP at 20-cm depth immediately under the emitters maintained to be higher than ?5, ?10, ?15, ?20 and ?25 kPa after sunflower establishment. Drip irrigation consistently created a favourable soil moisture and low-salinity region in the root zone when the SMP was maintained higher than ?25 kPa. The sunflower dry seed yield decreased by 3.8 % for each unit increase in seasonal average soil salinity in the root zone. Plant vegetative growth, yield characteristics, irrigation frequency and irrigation amount all increased with the increase in SMP from ?25 to ?5 kPa, and the highest irrigation water use efficiency was available when the SMP was between ?10 and ?15 kPa (the amount of applied water was around 750 mm). Leaching of salts by drip irrigation gradually turned the very strongly saline soil into a moderately saline soil. This research suggests that drip irrigation can be successfully used in oleic sunflower cultivation in this highly saline soil and a SMP threshold between ?10 and ?15 kPa is suggested for irrigation scheduling.     

FSAE赛车双横臂独立悬架系统设计

双横臂独立悬架对FSAE赛车行驶平顺性、操纵稳定性和安全性有着重要影响。依据FSAE大学生方程式大赛规则及参照经验值对包括轮距、轴距在内的整车参数进行确定。对轮胎、轮辋等部件进行选择,设计悬架立柱、摇臂部件,并利用CATIA软件进行三维模型的建立。基于ANSYS/Workbench协同仿真平台,对在转向和制动复合工况下的前立柱进行有限元分析。分析结果表明,满足材料的强度要求。设计的双横臂独立悬架为车辆悬架系统的结构优化和轻量化设计提供了参考。     

区域人水和谐评价指标体系及评价模型

为了评价区域人水和谐程度,在阐述人水和谐内涵的基础上,根据复杂系统及和谐论理论,构建了区域人水和谐评价指标体系.根据集对分析和可变模糊集理论,建立了集对分析可变模糊集模型,评价人水复合系统发展态势;以合作博弈理论为基本思想确定系统"理想发展状态",结合距离协调度模型,建立了合作博弈距离协调度模型,评价人水复合系统协调度;以发展态势和协调度为基本依据,采用乘法合成模型综合评价区域人水复合系统和谐度.将上述模型应用于陕西省人水复合系统,评价2000—2009年人水系统和谐程度,评价结果显示陕西省人水系统和谐度呈现缓慢上升趋势,但均处于第I,II等级,属于不和谐或临界和谐状态.说明陕西省人水和谐程度仍处于较低水平,比较符合陕西省目前实际现状.将此模型与模糊综合评价模型的评价结果进行对比分析,评价结果基本一致,表明该模型有效可行,结果可靠.     

嫁接茶树光合特性研究

在田间条件下研究了3种不同嫁接组合茶树(乌牛早／鸠坑，浙农l13／鸠坑，福建水仙／鸠坑)的光合特性。结果表明：嫁接三年后的茶树净光合速率(Pn)较接近于砧木品种。嫁接茶树光合日变化曲线“单峰”、“双峰”都有出现。Pn与相关生理生态因子，不同季节影响光合作用的主导因子有所不同，夏季Pn与蒸腾速率(E)呈极显正相关，冬季与叶面光合有效辐射(Qleaf)呈极显相关。     

Application of electrospun polyurethane web to breathable water-proof fabrics

Electrospun web may possibly be widely applied to protective garments or specialty textiles due to its high level of protection as well as comfort. Of particular interest in this study is to develop waterproof-breathable fabric by applying electrospun web of polyurethane directly onto the substrate fabric. The optimal electrospinning condition was examined with regards to the concentration, applied voltage and tip-to-collector distance. Solvent-electospinning of polyurethane was performed at the optimum condition, using N,N-dimethylacetamide as solvent. The thickness of 0.02 mm of electrospun web was applied onto the polyester/nylon blended fabric. For comparison, the polyester/nylon fabrics were coated with 0.02 mm thickness of polyurethane resin membranes adopting four different conditions. The electrospun PU web/fabric was compared to resin coated fabrics in terms of water-proof and breathable properties. The electrospun web applied fabric showed higher air permeability, vapor transmission, and thermal insulation properties than resin coated fabrics, which can be translated as greater comfort sensation of electrospun applied fabrics. However, water resistance value of electrospun web applied fabric did not reach that of resin coated fabrics.     

Effect of pineapple protease on the characteristics of protein fibers

A pineapple protease, bromelain, was used to improve the dyeing properties of protein fibers such as wool and silk. The optimal condition for the activity of the pineapple protease was about 60 °C at pH 7. The wool and silk were treated with the protease extracted from a pineapple and the K/S values of the dyed wool and silk were measured using a spectrophotometer in order to compare the dye uptake. The protease treatment enhanced the dyeing properties of protein fibers without severe changes in mechanical properties. The surface appearances of protease-treated fibers were observed by microscopy.     

应用土壤质地预测干旱区葡萄园土壤饱和导水率空间分布

田间表层土壤饱和导水率的空间变异性是影响灌溉水分入渗和土壤水分再分布的主要因素之一,研究土壤饱和导水率的空间变化规律,有助于定量估计土壤水分的空间分布和设计农田的精准灌溉管理制度。为了探究应用其他土壤性质如质地、容重、有机质预测土壤饱和导水率空间分布的可行性,试验在7.6 hm2的葡萄园内,采用均匀网格25 m×25 m与随机取样相结合的方式,测定了表层(0～10 cm)土壤饱和导水率、粘粒、粉粒、砂粒、容重和有机质含量,借助经典统计学和地统计学,分析了表层土壤饱和导水率的空间分布规律、与土壤属性的空间相关性,并对普通克里格法、回归法和回归克里格法预测土壤饱和导水率空间分布的结果进行了对比。结果表明:1)土壤饱和导水率具有较强的变异性,平均值为1.64 cm/d,变异系数为1.17;2)表层土壤饱和导水率60%的空间变化是由随机性或小于取样尺度的空间变异造成;3)土壤饱和导水率与粘粒、粉粒、砂粒和有机质含量具有一定空间相关性,而与土壤容重几乎没有空间相关性;4)在中值区以土壤属性辅助的回归克里格法对土壤饱和导水率的预测精度较好,在低值和高值区其与普通克里格法表现类似。研究结果将为更好地描述土壤饱和导水率空间变异结构及更准确地预测其空间分布提供参考。     

羊草对盐碱胁迫的生理生化响应特征

研究羊草对盐碱胁迫生理响应特征,旨在找出羊草耐盐碱范围及其对盐碱地改良的应用潜力。通过模拟5组不同盐碱梯度土壤胁迫试验(p H值为7.61、8.05、8.33、8.73、9.37,电导率为0.109、0.301、0.437、0.486、0.591 m S/cm),研究了羊草体内离子含量和运输能力、有机小分子渗透调节和保护酶活性变化。结果表明,盐碱胁迫由低到高,超氧化物歧化酶和甜菜碱在中度盐碱胁迫(p H值8.33,电导率0.437 m S/cm)积累最多,其他测定的耐盐碱物质,钠离子、脯氨酸、丙二醛、有机酸(草酸、柠檬酸、酒石酸)、过氧化物酶、过氧化氢酶、可溶性总糖、可溶性蛋白均呈直线增加。在盐碱胁迫条件下,羊草叶片中积累的钾离子、甜菜碱、有机酸、可溶性蛋白高于根茎,而脯氨酸、丙二醛、保护酶(超氧化物歧化酶、过氧化物酶、过氧化氢酶)、可溶性总糖叶片中含量低于根茎。根茎大量积累保护酶、脯氨酸及丙二醛有助于防止盐碱环境下根茎中膜过氧化,并保持根茎正常的渗透调节能力,从而有利于将K+等养分运送到叶片。在盐碱胁迫下,羊草叶片主要积累甜菜碱和有机酸进行渗透调节。该试验结果表明,羊草根茎和叶片在不同盐碱胁迫条件下各耐盐碱生理指标均产生一系列适应性反应,使其在盐碱环境正常生长,进而降低土壤盐碱性。该研究可为耐盐碱饲草选育及根茎型禾草改良盐碱化草地提供理论和实践依据。