新型硝化抑制剂对膜下滴灌棉田抑制效果及棉花产量的影响

[目的]研究2种含氯甲基吡啶硝化抑制剂在滴灌条件下对土壤氮素转化及棉花产量的影响.[方法]在石河子农科中心设置硝化抑制剂棉花滴灌小区试验.[结果]供试的2种硝化抑制剂随水滴施第6 d后均表现显著的硝化抑制效果,土壤NH4+-N较对照增加3.82;～211.25;,NO3--N降低56.2;～77.12;;表观硝化率较对照处理降低2.66～52.83个百分点;提高氮肥利用率1.54～4.15个百分点;1 hm2增产籽棉202.5～247.5 kg,增产幅度3.43;～4.3;,新增经济效益1 059～1 306.5元.[结论]滴灌条件下硝化抑制剂随水滴施,简单易行,能够有效改善棉株的氮素营养水平,增产效果显著.     

不同铵硝配比营养液对生菜内源激素的影响

采用水培试验探讨了不同铵氮和硝氮配比(简称铵硝配比)对不同品种生菜(Lactuca sativa L.)内源激素的影响.结果表明,不同铵硝配比对生菜根系和叶片中的内源激素含量有显著影响.随着营养液中NH4+-N比例的增加,生菜根系和叶片的生长素(IAA)含量及异戊烯腺嘌呤(iPAs)含量均随着增加,并在营养液中NH4+-N比例为25％时达最高.然后,随着NH4+-N比例进一步增加到50％,生菜根系和叶片的IAA含量及iPAs含量反而下降.生菜根系和叶片的脱落酸(ABA)含量随着营养液中NH4+-N比例的增加而下降,并在营养液中NH4+-N比例为25％时达最低.然后,随着NH4+-N比例进一步增加到50％,生菜根系和叶片的ABA含量反而增加.随着试验进程从4叶期推进到6叶期、8叶期,供试生菜根系和叶片中的内源激素水平随之下降.     

利用MODIS—NDVI进行草地生产力估测研究——以奇台县草地为例

利用2000年到2009年的MODIS影像,结合地面GPS精确定点调查,以奇台县草地为研究对象,建立天然草地牧草产量遥感模型,分析奇台县十年草地的生产力变化情况。结果表明:从2000年到2009年,奇台县的草地产量和盖度都有一定的提高,其中2003年、2007年和2009年草地产量有明显的提高,分别为1529.8千克/公顷、1755.5千克/公顷和1793.7千克/公顷,2008年由于奇台县降水量减少,盖度与产量有明显的下降。     

Distribution of Total and DTPA‐Extractable Zinc,Copper, Manganese,and Iron in Vertisols of India

Abstract

Vertisols of India are developed over isohyets of 600 to 1500 mm, and their chemical cycles are set by drainage, landforms, and particle size, which results in variable pedogenic development within the otherwise homogeneous soils. The purpose of this study was to identify pedogenic processes in the distribution of total and DTPA‐extractable zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe). The soils are developed over basaltic parent material of Cretaceous age. Soil samples were drawn from genetic horizons of the 13 benchmark profiles and analyzed by using HF–HClO₄ acid for total and DTPA extraction. Correlation coefficients were calculated taking all samples together. The total concentration varied from 24 to 102 mg kg^?1 for Zn, 21 to 148 mg kg^?1 for Cu, 387 to 1396 mg kg^?1 for Mn, and 2.36 to 9.50% for Fe. Their variability was proisotropic and haplodized, and their concentrations increased with advancing isohyets. Within the isohyets, hindrance in drainage caused retention of Zn and Cu but loss of Fe. The piedmont soils had more Fe than alluvium soils. The spatial distribution of total contents of Zn, Cu, and Fe was influenced by the pedogenic processes associated with Haplusterts but not with provenance materials. Surface concentrations of the elements by biotic lifting and/or harvest removal were negated by the pedoturbation that further contributed to the irregular distribution of the elements in the profiles. Total Zn and total Cu had positive coefficients of correlations with coarse clay, whereas total Mn and total Fe were positively correlated with fine clay. The DTPA‐extractable forms were functions of isohyets and drainage and showed association with organic carbon content and coarse clay.     

针叶林岩-土-植系统中毒害元素赋存规律研究

以成都天台山及其周边区域马尾松、柳杉、杉木林为研究对象,通过野外调查、室内测试分析,开展了针叶林岩—土—植系统中毒害元素赋存规律研究,结果表明:3种针叶林立地As,Hg元素岩石库风化对土壤地质潜在输入次序为杉木林地、马尾松林地、柳杉林地;5种毒害元素中As,Hg,Cd,Pb4种元素均表现出在土壤表层有累积态势;而As元素在马尾松、柳杉等植物体运移能力强;Hg元素在杉木体内容易迁移;Al元素在杉木、柳杉内部的运输能力高;Pb元素在柳杉、马尾松中有较高的迁移能力;Cd在马尾松内容易发生转移;3种针叶树种对Pb,Hg,Cd的赋存能力高,而对Al,As两种元素的赋存能力较低。     

甘肃黄土高原区潜在蒸散量时空变化与成因研究

基于甘肃黄土高原区12个气象站点1960—2008年逐日气温、降水、风速、日照时数、太阳总辐射和相对湿度数据,应用Penman—Monteith模型和Kriging插值法,分析了其潜在蒸散量的时空变化及其影响因子。结果表明:近49a来,陇中北部冷温带半干旱区和陇中南部冷温带半湿润区的潜在蒸散量均呈上升趋势。在四季中,潜在蒸散量的值夏季最大,春秋季次之,冬季最小。潜在蒸散量空间差异显著,潜在蒸散量的值表现为自北向南递减,其中最大值在景泰为1 105.82mm,最小值在岷县为772.31mm。相关分析表明,研究区年均潜在蒸散量所受气候因子的影响不尽相同,其中,陇中北部冷温带半干旱区为太阳总辐射和日照时数,而陇中南部冷温带半湿润区为太阳总辐射和最高气温。辐射项主要受太阳总辐射和最高气温影响,动力项主要受风速影响,辐射项的值都远大于动力项。不同气候区辐射项均呈上升趋势,但动力项有所不同,在陇中北部冷温带半干旱区呈下降趋势,斜率为-0.631mm/a,在陇中南部冷温带半湿润区呈上升趋势,斜率为0.415mm/a。     

Weed and fertility management using maize/soyabean intercropping in the north‐western Himalayas

Abstract

In a field experiment conducted on a moderately fertile silty clay loam soil in the north‐western Himalayas, growing one or two rows of soyabean (Glycine max L.) as an intercrop in maize (Zea mays L.) reduced weed numbers and weights significantly and increased maize yields. Sowing two rows of soyabean had a better effect than one row, with maize at a constant sowing density. The maize equivalent yield increased significantly with intercropping in the ratio 1:2 (maize:soyabean rows) as compared to maize alone or maize + soyabean in alternate rows, when all these trials were supplied with the full recommended amount of fertilizer. The maize yield in trials with half the recommended fertilizer amount in the intercropped system was similar to that of maize alone supplied with the full fertilizer dose. The weeds were effectively controlled and yields of maize and soyabean were increased with pre‐emergence application of alachlor at the rate of 2.5 kg a.i./ha or with three hand weedings.     

1981—2010年新民市气候变化特征分析

以1981—2010年新民市实测气象资料以及灾害情况为基础,分析了新民市1981—2010年近30年来气候变化的主要特征。结果表明,近30年新民市气温逐渐升高,降水量呈现上升趋势,日照时数呈下降趋势,无霜期日数延长。分析气候变化对农业产生的影响,并进一步提出应对措施。     

浅析英译汉中的误译

本文对英译汉中的误译现象进行了归纳总结 ,并从不同侧面剖析了误译现象发生的根源 ,找出问题的症结及规律 ,从反面给人以启迪和帮助     

兰州市主要动物性食品的供求趋势

在定性分析的基础上,利用灰色系统模型,对兰州市主要动物性食品供求趋势进行了定量预测和分析,探讨了解决供求矛盾的基本途径和具体措施。