苹果种植技术进步贡献率的测算与分析

技术进步贡献率是衡量技术进步对产业增长贡献份额的综合指标.选取1991-2009年苹果产量、物质、劳动、土地等投入产出数据,运用C-D生产函数和索罗余值方程,对我国苹果种植环节的技术进步贡献率进行测算与分析.结果表明,1995-2009年间,我国苹果种植环节技术进步率对苹果产出增长的平均贡献率为97.75％,土地投入增长率的平均贡献率为17.18％,而物质和劳动投入增长对产出增长的贡献率为负值.技术进步已成为促进苹果种植产出增长的首要因素,我国苹果种植正在由以传统要素密集投入为特征的外延式发展模式向以技术进步为特征的内涵式发展模式转变.     

On the relationships between glucocorticoids and feed efficiency in beef cattle

Improvement in the utilization of feed in livestock is an important target of breeding and nutritional programs. Recent evidence indicates a potential association between feed efficiency and fecal cortisol metabolites, which could eventually be used as an indirect assessment of this trait. This evidence is more comprehensively evaluated in here with samples for plasma cortisol (PC; ng/ml) and fecal cortisol metabolites (FCM; ng/ml) collected more often during the entire finishing phase in beef steers. Individual daily feed intake of 112 steers fed a high-moisture corn-based and haylage diet was measured over 168 d. Body weight, blood and fecal samples were collected every 14 d and ultrasound measures of backfat thickness and longissimus muscle area were taken every 28 d. Four productive performance traits were calculated: daily dry matter intake (DMI), average daily gain (ADG), feed to gain ratio (F:G) and residual feed intake (RFI). At the end of the feedlot phase, steers were ranked according to RFI and samples were analyzed for PC and FCM from the 32 steers with greatest and 32 steers with lowest feed efficiency. In addition, a sub-group of 12 steers from each of these two groups with divergent feed efficiency were subjected to hourly blood sampling for 24 h. Less efficient steers had greater DMI, F:G and consumed 1.5 kg/d more DMI (P<0.05) than steers with improved feed efficiency. No differences (P>0.10) in PC over the 12 biweekly sampling periods between steers with divergent feed efficiency were observed. However, a trend toward significance between 19:00 and 02:00 h over the hourly sampling evaluation was noticed, with the sub-group of more feed efficient steers presenting higher levels of PC in this period of the day (P=0.08). On the other hand, FCM levels displayed a distinct pattern between RFI groups over the biweekly sampling period, with more efficient cattle presenting greater levels of these metabolites (P<0.05). This study reinforces the positive association between improved feed efficiency and FCM levels over the finishing phase; and the lack of association between feed efficiency and PC when single samples are collected every two weeks through a single jugular venipuncture performed after handling the cattle for sampling. Further studies to develop sampling protocols for assessing FCM as an indicator trait for feed efficiency are warranted, as well as, studies to understand the role of endogenous glucocorticoids in the performance of the bovine.     

果园草被残体浸提液对日本草种子发芽与幼苗生长的化感效应

采用生物检测方法，研究果园草被植株残体浸提液处理后的日本草种子萌发和幼苗生长的变化。结果表明：（1）10％浓度浸提液处理果园土壤时，会影响果园杂草的萌发及优势种日本草根冠比；（2）用不同浓度果园草被的植株残体浸提液砂培日本草种子时，都会降低发芽势和发芽率，且竹节草处理的效果最明显，达到差异显著（p<0.05）或极显著水平（p<0.01）；（3）百喜草处理促进日本草幼苗生长，宽叶雀稗处理效果相反；竹节草处理5.0％和10.0％时抑制日本草根生长，而其它处理促进了日本草根生长；（4）不同处理的日本草生物量都不同程度地小于对照，且竹节草处理的效果最明显，达到差异显著或极显著水平；（5）各处理对受体日本草的化感综合效应指数都小于对照，起抑制作用，竹节草处理抑制效果最明显。     

大豆蚜玻璃管药膜法敏感毒力基线的建立

以采自吉林长春地区田间的大豆蚜在室内不接触药剂饲养25代以上,利用玻璃管药膜法建立了大豆蚜对新烟碱类、氨基甲酸酯类、拟除虫菊酯类、有机磷类共10种杀虫剂3.5 h的敏感毒力基线.结果表明:大豆蚜对这10种杀虫剂的敏感度较高,LC50从小到大依次为:吡虫啉(0.105 μg·g-1)、功夫菊酯(0.924 μg·g-1)、溴氰菊酯(1.216 μg·g-1)、毒死蜱(1.557 μg·g-1)、灭多威(1.918 μg·g-1)、克百威(3.927 μg·g-1)、马拉硫磷(5.125 μg·g-1)、辛硫磷(12.551μg·g-1)、氧乐果(13.190 μg·g-1)、氰戊菊酯(28.569 μg·g-1).所测得结果可作为敏感毒力基线,并为大豆蚜的抗药性监测提供理论依据.     

烯唑醇在鸭梨果实中的残留降解动态研究及安全性评价

[目的]分析烯唑醇在鸭梨果实中的残留情况并进行安全性评价,为无公害果品的生产提供理论依据。[方法]用GC-MS测定烯唑醇含量。[结果]烯唑醇在鸭梨果实中的降解较快,半衰期为12.47d。12.5%烯唑醇可湿性粉剂按施药浓度3000倍,3～5次,最后1次喷药21d采样测定,其残留量为0.0485～0.0528mg/kg;按施药浓度1500倍,3～5次,喷药,其残留量为0.0603～0.1070mg/kg。说明只有按1500倍液喷药5次,烯唑醇在鸭梨果实中的残留超出最高残留限量标准。[结论]烯唑醇按推荐剂量使用是安全的。     

气相色谱法测定植物性食品中联苯菊酯农药残留的不确定度分析

建立气相色谱法测定植物性食物中联苯菊酯农药残留量的数学模型,并对测量结果的不确定度来源进行分析。     

典型蔬菜种植区土壤中有机氯农药及植物杀菌剂残留研究

[目的]研究山东枣庄地区蔬菜种植区土壤中有机氯农药及植物杀菌剂代森锌的残留情况。[方法]选取山东枣庄地区3个较为典型的蔬菜种植区为调查对象,采用土壤系统布点法,对土壤中的有机氯农药六六六、DDT、氯丹、七氯及代森锌进行采样分析。[结果]六六六、DDT、氯丹、七氯全部被检出,残留量为低浓度水平,代森锌未检出。DDT、六六六、七氯、氯丹的单因子污染指数最大值分别为0.648 0、0.269 0、0.044 0、0.000 4,属于土壤环境质量评价等级Ⅰ级,为无污染级别。采样区1、2、3的土壤综合污染指数平均值分别为0.414 7、0.191 8、0.122 7,污染等级为清洁(安全)。[结论]3个典型蔬菜种植基地土壤环境质量整体良好。     

Effects of crop residue management on winter durum wheat productivity in a long term experiment in Southern Italy

A long-term experiment comparing different crop residue (CR) managements was established in 1977 in Foggia (Apulia region, southern Italy). The objective of this study was to investigate the long-term effects of different types of crop residue management on main yield response parameters in a continuous cropping system of winter durum wheat. In order to correctly interpret the results, models accounting for spatial error autocorrelation were used and compared with ordinary least square models.Eight crop residue management treatments, based on burning of wheat straw and stubble or their incorporation with or without N fertilization and irrigation, were compared. The experimental design was a complete randomized block with five replicates.Results indicated that the dynamics of yield, grain protein content and hectolitric weight of winter durum wheat did not show any decline as usually expected when a monoculture is carried out for a long time. In addition, the temporal variability of productivity was more affected by meteorological factors, such as air temperature and rainfall, than CR management treatments. Higher wheat grain yields and hectolitric weights quite frequently occurred after burning of wheat straw compared with straw incorporation without nitrogen fertilization and autumn irrigation and this was attributed to temporary mineral N immobilization in the soil. The rate of 50 kg ha⁻¹ of N seemed to counterbalance this negative effect when good condition of soil moisture occurred in the autumn period, so yielding the same productive level of straw burning treatment.     

桑树不同季节施用杀虫剂虫螨腈对家蚕的残留毒性调查

虫螨腈因其对家蚕的低毒性而成为桑树害虫防治药剂之一。为了确保桑园施用虫螨腈对家蚕的安全性,分别于春、夏、秋季对桑树喷施虫螨腈后,调查药剂对家蚕的残毒性及家蚕的中毒情况,结果表明不同季节桑树喷施虫螨腈对家蚕的残毒性差异较大。夏季以24%虫螨腈悬浮剂3 000倍稀释药液喷施桑树后3 d采叶饲养对3龄期家蚕基本安全,1000、2000倍稀释药液喷施后5d采叶饲养对3龄期家蚕已无致死性;春季3种浓度药液喷施后7 d采叶饲养仍造成3龄期家蚕100%死亡。夏蚕期3龄期家蚕饲喂1000倍稀释药液喷施后1h的桑叶后即出现中毒死亡,而中秋蚕期、春蚕期的3龄期家蚕食下相同毒叶分别在1、3d后才出现中毒死亡现象。此外,调查虫螨腈对不同龄期家蚕的残毒性,表明对5龄期家蚕的残毒性明显低于3、4龄期的家蚕,因此建议在家蚕4龄期之前尽量不用虫螨腈防治桑园害虫。     

Phytotoxic Effects of Residual Glufosinate on the Nitrogen Assimilation of Transplanted Rapeseed Seedlings

Herbicide application is an efficient method to control weed growth in modern agriculture production, but there is concern about the ecological impact of unwanted herbicide residues in the soil. Rapeseed varieties ZS11 and D148 were used to evaluate the phytotoxic effects of residual glufosinate on the assimilation of nitrogen (N) in rapeseed seedlings transplanted to untreated [0 g hm^?2 glufosinate] or treated [450 g hm^?2 and 900 g hm^?2 glufosinate] soils. Glutamine synthetase (GS) and glutamate dehydrogenase (GDH) activities, the contents of ammonium (NH₄⁺), free amino acids (FAA), and soluble protein (SP), and seedling dry weight (DW) were determined at 5, 8, 11, 20, 40, and 70 d post-transplant. Both concentrations of glufosinate induced physiological phytotoxicity on the N assimilation of transplanted seedlings of both varieties, as their leaves and roots presented reduced GS activities and SP contents, and increased GDH activities, and NH₄⁺ and FAA content. Glufosinate phytotoxicity on the N assimilation of transplanted seedlings reached a plateau at 11 to 20 d. further, GDH in roots and GS in leaves were still significantly different at 70 d. Meanwhile, ZS11 might be more sensitive to glufosinate than D148 since ZS11 had more variation than D148 at the same treatment, and the overdose of glufosinate more strongly inhibited N assimilation than the recommended dose. Therefore, it is essential to apply a suitable glufosinate dose to the transplanted variety, to minimize adverse effects on crops and the environment.

Abbreviations: N, Nitrogen; GS, Glutamine synthetase; GDH, glutamate dehydrogenase; NH₄⁺, ammonium; FAA, free amino acids; SP, soluble proteins; DW, Dry weight; ANOVA, one-way analysis of variance; NO₃^?, nitrate; OECD, Organisation for Economic Co-operation and Development; PPT, phosphinothricin; USEPA, United States Environmental Protection Agency