青海高原主要农业区50年初·终霜冻日变化特征及分布规律分析     

汪青春  胡玲  刘宝康 《安徽农业科学》2012,40(33):16265-16269

选取青海东部农业区的西宁、大通、互助、乐都、民和、湟源、湟中、循化、化隆、贵德和尖扎11个站及柴达木盆地的都兰、诺木洪、大柴旦、格尔木、德令哈、冷湖、天峻、小灶火、茶卡9个站,用1961～2010年逐日最低气温资料,分2、0、-2℃3个温度等级,分析50年来初、终霜冻日及无霜期的变化趋势和年代际变化特征及分布规律。结果表明,20世纪80年代以后初霜冻日逐年推迟、终霜冻日逐年提前,无霜期延长,东部农业区进入21世纪这种情况最为明显,而柴达木盆地80年代最为明显;与60年代相比,21世纪以来初霜冻日推迟,终霜冻日提前,无霜期东部农业区延长20 d,柴达木盆地延长32 d,柴达木盆地初、终霜冻历年变化比东部农业区大,无霜期较东部农业区延长明显。  相似文献   

美丽青背姬小蜂寄生和繁殖特性研究   总被引：2，自引：0，他引：2  

宋丽群 高燕许再福  古德就 《昆虫天敌》2004,26(3):113-121

美丽青背姬小蜂Chrysonotomyia formosa(Westwood)是美洲斑潜蝇的优势天敌，在美洲斑潜蝇的自然控制中发挥着非常重要的作用。本文对其寄生和繁殖特性进行了研究，结果表明：美丽青背姬小蜂主要将卵产于寄主幼虫的腹部，1头寄主幼虫体内可产1-5粒卵，但只有1粒卵能完成发育成为成蜂；不同温度下，雌蜂的繁殖能力不同，其中雌蜂在23℃时有最大的产卵量和最高的致死寄主个体数；提供10％的蜂蜜水可以显著提高雌蜂对寄主的寄生数、产卵量、刺死寄主数和总致死寄主数；美丽青背姬小蜂也能进行产雄孤雌生殖；营孤雌生殖的雌蜂与有性生殖的雌蜂在寿命、寄生寄主数、产卵数、刺死寄主数和总致死寄主数之间差异不显著。  相似文献   

Chemical and environmental factors driving germination of Solanum americanum seeds     

Csar Tiago Forte  Ubirajara Russi Nunes  Alberto Cargnelutti Filho  Leandro Galon  Leonardo Chechi  Rodrigo Roso  Andr Dalponte Menegat  Emanuel De Oliveira Rossetto  Milena Barretta Franceschetti 《Weed Biology and Management》2019,19(4):113-120

Solanum americanum Mill. is a weed that occurs with a number of crops, and it is known for its high seed production and its staggered germination. The objective of this work was to evaluate the germination behavior of S. americanum seeds under the influence of chemical and environmental factors. In the laboratory, we tested the effect on germination of (i) constant and alternating temperatures, (ii) seed washing, (iii) exposure time and concentration of chemical treatments and (iv) seeding depth and soil covered with plant residue on seedling emergence. The variables analyzed were germination percentage, germination rate index, seedling emergence and length of the seedlings. The results indicated that alternating temperatures are the main way to promote germination of S. americanum; however, chemical treatments can help to increase the germination percentage and rate index. There was no increase in germination with seed washing, with the exception of KNO₃ application. A GA₃ concentration of 0.84 g L^?1 and an exposure time of 21.22 h in 0.2% of KNO₃ promoted the highest germination of S. americanum. Germination occurs when seeds remain on the soil surface and are not covered by crop residue.  相似文献   

玉米籽粒水分的快测法误差分析     

阎晓光  杜艳伟  李洪  董红芬  李爱军  王国梁  周楠 《作物杂志》2020,36(5):170-21

以山西省中晚熟区域试验中37个玉米品种为试验材料,用PM-8188-A型谷物水分测定仪在4个环境温度下对玉米籽粒含水率进行水分快测,与传统标准烘干法测定值比较,利用回归分析建立对应的玉米籽粒真实水分数学方程,减小了电容式快测法在田间测定玉米籽粒水分过程中受环境温度影响而导致的误差,对育种家在田间选择含水率低的玉米品种方面具有一定应用价值。温度为10℃~25℃时,电容式快测法测定值随着温度的提高有变大趋势,20℃时测定的误差值最小。  相似文献   

不同生物质来源和热解温度条件下制备的生物炭对菲的吸附行为   总被引：3，自引：1，他引：3  

颜钰  王子莹  金洁  邱梦怡  韩兰芳  孙可 《农业环境科学学报》2014,33(9):1810-1816

以三种来源(猪粪便、玉米秸秆和松树木屑)的生物质为原料,分别在250℃和400℃温度条件下制备生物炭,对其理化性质进行表征,并研究菲在所选生物炭上的吸附行为及可能存在的吸附机制。结果显示,生物炭的理化性质随着生物质来源和热解温度条件的不同而有明显的变化;与250℃下制备的生物炭相比,400℃下制备的生物炭极性官能团数量更少,芳香度更高,疏水性更强,比表面积更大,孔结构发育更加完全,灰分含量更高;同一温度下,植物来源的生物炭比动物来源的生物炭的比表面积大,而动物来源的生物炭的灰分含量明显高于植物来源的生物炭。所有生物炭对菲的吸附行为都可以用Freundilich模型进行很好的拟合,且吸附等温线均显示出非线性;在猪粪便和玉米秸秆制备的生物炭中,400℃比250℃条件下制备的生物炭对菲有更强的吸附能力,表明吸附能力与热解温度有关;且同一热解温度下,动物来源的生物炭样品的吸附能力高于植物来源的生物炭样品,可能是由于其含有更多的灰分。Freundlich非线性指数n值与比表面积和芳香度之间均存在负相关关系,说明菲在生物炭上的吸附不仅有疏水效应,可能还存在着孔填充效应和π-π电子供体受体(EDA)反应等吸附机制的贡献。  相似文献   

Canopy reflectance, thermal stress, and apparent soil electrical conductivity as predictors of within-field variability in grain yield and grain protein of malting barley   总被引：1，自引：0，他引：1  

Carl-Göran Pettersson  Mats Söderström  Henrik Eckersten 《Precision Agriculture》2006,7(5):343-359

Three consecutive crops of malting barley grown during 2002–2004 on clay-loam on a Swedish farm (59°74’ N, 17°00’ E) were monitored for canopy reflectance at growth stages GS32 (second node detectable) and GS69 (anthesis complete), and the crops were sampled for above ground dry matter and nitrogen content. GPS-positioned unfertilised plots were established and used for soil sampling. At harvest, plots of 0.25 m² were cut in both fertilised and unfertilised plots, and 24 m² areas were also harvested from fertilised barley. The correlations between nine different vegetation indices (VIs) from each growth stage and yield and grain protein were tested. All indices were significantly correlated (at 5% level) with grain yield (GY), and protein when sampled at GS69 but only four when sampled at GS32. Three variables (the best-correlated vegetation index sampled at GS32; an index for accumulated elevated daily maximum temperatures for the grain filling period, and normalised apparent electrical conductivity (ECa) of the soil) were sufficient input in the final regressions. Using these three variables, it was possible to make either one multivariate (PLS) regression model or two linear multiple regression models for grain yield (GY) and grain protein, with correlation coefficients of 0.90 and 0.73 for yield and protein, respectively.  相似文献   

Biodegradation of sunflower hulls with different nitrogen sources under mesophilic and thermophilic incubations     

Conghos  María M.  Aguirre  María E.  Santamaría  Raúl M. 《Biology and Fertility of Soils》2003,38(5):282-287

The decomposition of sunflower hulls and mixtures of sunflower hulls and other crop residues was examined under mesophilic (25°C) and thermophilic (50°C) temperatures during a 45-day incubation. Four treatments were set up: sunflower hull, sunflower hull+5% alfalfa, sunflower hull+5% vetch, sunflower hull+0.1% urea, to asses the efficiency of composting. Changes in total organic C (TOC), oxidizable C, N, pH, electrical conductivity (EC), and different fibre fractions—cellulose, hemicellulose and lignin—were determined. TOC decreased by 13–21% at 25°C and 25–41% at 50°C and the largest loss of C was for hulls amended with vetch residues and urea. Loss of oxidizable C was not affected by either the temperature or the treatments. The largest loss of cellulose occurred at 50°C in all the treatments. The hemicellulose content of the sunflower hulls alone and in the treatment with urea was significantly different with respect to the other treatments, whereas lignin content showed either a small increase (1.6% in sunflower hulls amended with alfalfa at 50°C and 1.8% in sunflower hulls with urea at 25°C) or a decrease of between 2.5% and 19% in the other treatments. The C/N ratio never fell below 50:1 and the highest decrease was for the thermophilic incubation. Increases in EC and pH values accounted for 3 and 1.5 units, respectively, and occurred after a 45-day incubation for mesophilic and thermophilic conditions. In general the incubation at 50°C facilitated the decomposition of sunflower hulls with high C/N ratios and little N addition.  相似文献   

苹果片变温压差膨化干燥特性与动力学研究   总被引：5，自引：0，他引：5  

何新益  程莉莉  刘金福  黄宗海  杜先锋  汪姣 《农业机械学报》2012,43(5):130-135

探讨了膨化初始含水率和抽真空干燥温度对苹果片变温压差膨化干燥特性的影响,建立了苹果片变温压差膨化干燥动力学模型。结果表明:苹果片变温压差膨化干燥过程分为加速干燥、恒速干燥和减速干燥3个阶段,干燥过程大部分处于减速干燥;不同干燥条件下的苹果片变温压差膨化干燥满足Page方程;苹果片有效扩散系数在1.52×10-9～8.87×10-9m2/s范围内。所建模型可以预测干燥条件下的苹果片变温压差膨化干燥过程中含水率的变化,特定系数k、n与膨化初始含水率和抽真空干燥温度呈线性关系,相关系数r2分别为0.845、0.997。  相似文献   

1975～2013年秦岭牛背梁保护区气温变化研究     

冯林林  刘荣娟 《安徽农业科学》2015,(25):192-193

基于秦岭31个气象站点的气温数据,采用Krigi ng插值法、趋势分析法、M-K检验法研究了1975～2013年牛背梁保护区年尺度、季节尺度上的平均气温和极端气温的变化规律.结果表明,牛背梁保护区是全球气候变暖的敏感区域.年尺度上,近39年来平均气温与极端气温呈明显上升趋势,其中极端最低气温上升最为显著,且均在1994年发生了暖突变;季节尺度上,平均气温和极端气温除秋季呈下降趋势外,春季、夏季和冬季均表现上升趋势,四季气温的突变年份集中在20世纪90年末和21世纪初.  相似文献   

Growth and its partitioning in Prunus rootstocks in response to root zone temperature     

Peter Malcolm  Paul Holford  Barry McGlasson  Jann Conroy  Idris Barchia 《Scientia Horticulturae》2007

Rootstocks for stone fruit varieties differentially influence tree physiology and one possible explanation for these differences is that varieties vary in their response to root zone temperature (RZT). To examine the effects of RZT, two trials using actively growing plants of five different Prunus rootstocks with chill requirements between 100 and 1100 h were undertaken. Plants were grown at RZTs of 5, 13 and 19 °C for 6 weeks after which total dry matter accumulation and its partitioning amongst roots, stems and leaves was determined. In general, the magnitude of total dry matter and its component parts positively correlated with RZT and significant differences were found among varieties in the magnitude of total dry matter accumulation. Individual varieties ranked differently at the three RZTs with respect to total dry matter: in general, the same ranking was also seen in the ranking of each growth component. RZT significantly influenced partitioning causing differences in leaf, stem and root mass ratios. These differences were greatest at low RZTs and became less as RZT increased. Several patterns of partitioning were found. Firstly, the low chill varieties (Okinawa and Flordagold) were little affected by RZT with similar partitioning occurring at each RZT. Secondly, the higher chill varieties, Green Leaf Nemaguard (GL), Golden Queen (GQ) and Fay Elberta (FE), reacted more strongly to RZT and were particularly affected by the lowest RZT. For these varieties, the root mass ratio rose and stem mass ratio fell as RZT increased. However, with respect to leaf mass ratio, two different trends were found: the leaf mass ratio for FE and GQ positively correlated with RZT whilst the relationship for GL was negative. These findings suggest that the response to RZT is related to a variety's chill requirement; offer an explanation for differences in performance of rootstock–scion combinations at different locations; and will aid the development of more accurate tree performance models by taking RZT into account.  相似文献