7种杀菌剂对窄截盘多毛孢的毒力测定

采用菌落生长和速率法,选择多菌灵,灵锈宁等７种杀菌剂,单用或配对等量混用,对云杉雪霉病的主要病原菌之一窄截盘多毛孢进行毒力测定。结果表明：大多数混剂的毒力均显著高于单剂毒力,增效作用较大的混剂是：多菌灵＋代森锌,多菌灵＋粉锈宁,多菌灵＋福美砷,多菌灵＋退菌特,托布津＋退菌特,福美砷＋退菌特。     

基于双年份三季相光谱混合分解的耕地变化遥感检测方法初步研究——以甘肃省民勤县为例

为切实保护耕地,基于遥感技术对不同耕地演化类型,包括不变耕地、新增耕地、撂荒耕地和退耕耕地进行识别和检测,以民勤县为例,采用2010和2015年2个年份的春、夏、初冬地物景观三季相特点的Landsat TM/OLI数据作为主要数据源。依据不同耕地演化类型的季相变异规律和内部要素特征选取具有物理意义的端元丰度值、丰度值差值建立2年份混合决策树划分不同耕地演化类型。同时对比分析在2010和2015年各自决策树土地利用/覆被分类结果后比较提取的耕地演化类型。结果表明:民勤县大部分耕地未发生变化,新增耕地在各个区域均有一定量的分布且主要分布在下游;退耕耕地大面积分布在坝区;撂荒耕地主要分布在沙漠绿洲过渡带。研究表明通过能够与地物先验知识关联的端元丰度值、特征端元丰度的差值建立决策树可以有效实现不同耕地演化类型的检测。误差矩阵精度评价结果显示,基于混合决策树耕地演化类型提取结果在总体精度上要高于分类后变化检测的结果。     

杨桐的繁殖和培育技术试验研究

选取扬桐野生优良单株进行种子育苗、扦插、嫁接等多种方式的繁殖试验表明,嫩枝扦插的成活率可达８０％以上。模拟杨桐的生境特点,进行栽培试验,表明落叶乔木和常绿乔木与杨桐以２：１：１０的比例进行树种混交方法,对提高它的成活率、生长量、枝条质量是有效的。通过不同采枝量对其生长量的影响试验可知,采取合理的修剪方式能保证杨桐的持续利用。     

一年生混播人工草地生物量、品质及种间竞争的动态研究

作者在华北农牧交错带对燕麦和箭管豌豆单播及混播的一年生人工草地进行了生物量、品质及种间竞争的动态研究。结果表明：整个的生育期除蜡熟期、成熟期外,燕麦单据的产草量一直高于其它处理的产草量,燕麦50％ 箭管豌豆50％处理在蜡熟期、成熟期产草量表现最高;从开花期开始,各处理的单位面积粗蛋白质产量均显著（P＜0.05）高于燕麦单播的产量．而DNF、ADF含量又低于燕麦单播的含量;燕麦蜡熟期和箭管豌豆结荚期是牧草最佳的刈割期,以燕麦25％ 箭管豌豆75％和燕麦50％ 箭管豌豆50％混播比例为最好;从整个混播群落看,燕麦的干物质积累速率快,植株高,其竞争力超过箭管豌豆,箭管豌豆一直处于劣势地位。     

甲氰菊酯、辛硫磷混合剂在苹果中的残留降解

甲氰菊酯、辛硫磷及其混剂分别在苹果上使用后 ,定期取样气相色谱测定苹果上的残留量。研究结果表明单剂及混剂甲氰菊酯在苹果上的半衰期分别为 19.3天和 18.1天 ,单剂辛硫磷和混剂辛硫磷在苹果中的残留半衰期分别为 1.54及 1.4 6天 ,甲氰菊酯和辛硫磷单独使用或混合使用在苹果中的降解规律及降解速率常数没有显著差异。从甲氰菊酯和辛硫磷在苹果上残留角度考虑两者混合使用对环境是安全的。     

Laboratory and on‐farm evaluation of low‐cost salt mixtures for use during salinity acclimation and the nursery phase of Pacific white shrimp (Litopenaeus vannamei)

The current study evaluates the efficacy of a low‐cost salt mixture (LCSM) to replace expensive reconstituted sea salt (RSS) in the salinity acclimation and nursery phase of Pacific white shrimp under laboratory and farm conditions. LCSM was formulated to yield sodium, potassium, calcium and magnesium concentrations closely comparable to that of diluted seawater. Laboratory‐based nursery trials were conducted at 2, 6 and 15 g/L salinities, incrementally replacing RSS with LCSM (25%, 50%, 75% and 100%) at four replicates per treatment. Thirty postlarvae were reared for 7 days in 24‐L aquaria during the 2 and 6 g/L trials, while the nursery trial for 15 g/L salinity was conducted for 21 days with 400 postlarvae stocked in 150‐L tanks. On‐farm evaluation of LCSM was carried out in two tank‐based systems installed on levees adjacent to shrimp production ponds. RSS was incrementally replaced with LCSM (0%, 50%, 75% and 100%) and 100 postlarvae stocked into each 800‐L tank. Salinity acclimation was done from 30 g/L to 6 or 1.5 g/L within 2–3 days by pumping water from adjacent shrimp production ponds. Following salinity acclimation, the S4 system maintained flow‐through at 1.5 g/L, while N10 system was maintained static at 6 g/L salinity. At the conclusion, no significant differences were observed for either survival or growth of shrimp postlarvae between RSS and LCSM treatments at all salinities examined. Results reflect the potential use of LCSM to replace RSS, which could be an excellent solution to bring down the cost of production in inland shrimp aquaculture.     

复合动植物蛋白部分替代鱼粉对大菱鲆幼鱼生长、体成分及生理生化指标的影响

本研究设计5组等氮等能(粗蛋白为53%,能量为25KJ/g)的实验饲料,以60%的鱼粉饲料组作为对照(D1),豆粕∶花生粕∶鱼溶浆粉∶鸡肉粉(2∶1∶3∶2)的复合蛋白替代40%(D2)、50%(D3)、60%(D4)和70%(D5)的鱼粉,养殖大菱鲆幼鱼(Scophthalmus maximus L.)初始体重(53.0±0.2) g,养殖周期84 d,每天定时(08:00,16:30)投喂2次,投喂量为体重的1.5%～2%。实验结果显示,各处理组之间幼鱼存活率、饲料系数和摄食率均无显著性差异(P0.05);与对照组相比,D4和D5组增重率显著降低(P0.05);肥满度在D2组达到最高值,显著高于D3、D4和D5组(P0.05);脏体比(VSI)、肝体比(HSI)和肠体比(ISI)均在D2组达到最低值,均显著低于D5组(P0.05);复合动植物蛋白替代鱼粉对大菱鲆幼鱼全鱼水分和粗蛋白含量均无显著影响(P0.05);各替代组全鱼粗脂肪含量显著高于对照组(P0.05);全鱼灰分含量在D5组显著低于对照组(P0.05);各组间背肌水分、粗蛋白、粗脂肪和灰分含量均无显著性差异(P0.05);复合动植物蛋白替代鱼粉对鱼体肌肉非必需氨基酸和必需氨基酸总量无显著影响(P0.05);各替代组均显著提高了血清谷草转氨酶和谷丙转氨酶活性(P0.05);总蛋白浓度在D2组显著高于D4和D5组(P0.05);血糖浓度在D2和D3组显著低于其他3组(P0.05);D3、D4和D5组甘油三酯浓度和高密度脂蛋白浓度均显著低于对照组和D2组(P0.05);各替代组胆固醇和低密度脂蛋白浓度均显著低于对照组(P0.05);各组之间碱性磷酸酶浓度无显著差异(P0.05)。研究结果表明,复合动植物蛋白可有效替代50%鱼粉而不影响大菱鲆幼鱼生长性能和部分生理生化指标。     

Deposit structure and efficacy of pesticide application. 1: Interactions between deposit size,toxicant concentration and deposit number

Application of pesticides through a hydraulic nozzle produces deposits on a plant surface which have a spatial structure with elements of deposit size, number per area, and toxin per deposit. To investigate the relative contributions of these elements to the interaction of deposit structure and toxicant efficacy, we used a stochastic cellular automaton model of diamondback moth feeding on Bacillus thuringiensis (Bt)-treated cabbage – the Pesticide Dose Simulator (PDS) model. Data were analyzed using a specialized response surface approach called a mixture design. The advantage of this design was that it integrated the effects of deposit size, number per area and toxin per deposit on toxicant efficacy. Results from PDS simulations led to the following conclusions: (1) Deposit structure plays a major role in toxin efficacy. (2) Small deposits are not always the most efficacious. (3) Uniform coverage is not the best deposit structure if one is forced to limit application rates and field persistence. (4) Since uniform deposit structures allow an insect to live longer, uniform deposit structures should result in more insects acquiring sub-lethal doses. This may result in an interaction between ‘uniform coverage’ and the development of pesticide resistance in insect populations. (5) Percentage mortality and the level of crop protection are not necessarily correlated. Overall, these results help reconcile laboratory observations that small droplets are more efficacious with field observations that application of small droplets (eg from spinning disk sprayers) does not necessarily increase field efficacy. © 1999 Society of Chemical Industry     

农药新剂型——微乳粒剂配制的可行性研究

以三唑磷为模式农药,研究了一种外观为颗粒状、用水稀释后成微乳液的农药新剂型——微乳粒剂配制的可行性。以乳状液的中位径(D50)为因变量,各表面活性剂用量为自变量,采用混料均匀试验设计并结合偏最小二乘回归法筛选表面活性剂品种;用比例法与对分法优化各表面活性剂用量;采用旋转挤压造粒法造粒。将筛选获得的农乳500与农乳602号用于配制15%三唑磷微乳粒剂,其乳状液外观为淡蓝色透明状,分散相颗粒迁移速度为0,且不同水质(水硬度:0~3 420 mg/L,水温:10~50 ℃)下乳液稳定性均合格;乳状液D50为54.2 nm,粒径分布范围为15.7~122 nm,粒径增大速率为0.01%/min;乳状液在相对离心力10 730×g下离心5 min未发生相分离。结果表明:该三唑磷微乳粒剂的乳状液为微乳液,微乳粒剂可以成功配制。     

Using chemical seed dormancy breakers with herbicides for weed management in soyabean and wheat

Variable dormancies result in periodicity in the germination of weeds and make weed control a repetitive practice. Under some conditions, repeated applications of selective herbicides can lead to the dominance of perennial weeds like Cyperus rotundus . Our hypothesis was that applying a chemical dormancy breaker (DB ) plus herbicide mixture would better control a mixture of weed species. Three experiments were designed to develop a cost‐effective DB treatment and to evaluate its dose with herbicides tank‐mixtures for effective weed management. KNO ₃ and gibberellic acid GA ₃ as dormancy breakers offered comparable effects, but KNO ₃ was more economical than GA ₃. KNO ₃ at a 6% concentration was more effective in promoting weed germination than a 3% concentration in soyabean. A combination of KNO ₃ (6%) and pre‐emergence pendimethalin 0.75 kg a.i. ha^?1 + imazethapyr 0.10 kg a.i. ha^?1 controlled annual weeds by 99% and reduced C. rotundus growth by 83%. This treatment gave significantly higher soyabean yield and net returns. Similarly, a tank‐mixture comprising of clodinafop 0.06 kg a.i. ha^?1 + metsulfuron 0.006 kga.i. ha^?1 was more effective against weeds than pre‐emergence tank‐mix application of pendimethalin 0.75 kg a.i. ha^?1 + carfentrazone‐ethyl 0.02 kg a.i. ha^?1 and isoproturon 0.75 kg a.i. ha^?1. The use of pre‐emergence tank‐mixture of pendimethalin 0.75 kg a.i. ha^?1 + imazethapyr 0.10 kg a.i. ha^?1 should exhaust seed/tuber bank if repeated and reduce the application cost of herbicides by 50% and the dose, residue and cost of pendimethalin by 25%.