~(15)N示踪的水稻氮肥利用率细分

以粳稻武运粳23和超级杂交籼稻Y两优2号为供试品种,应用15N示踪方法研究不同时期施肥对水稻不同阶段氮肥利用率的影响,以确定不同时期施肥的最佳阶段氮肥利用率。结果表明,基肥在基肥阶段(移栽后的8 d左右)的吸收利用较低,2012年水稻基肥氮(15N)吸收量不到5 kg hm–2,2013年最大为7.5 kg hm–2,回收利用率在1.5%~11.5%之间;基肥主要是在蘖肥阶段(分蘖肥与穗肥之间)被吸收,其回收利用率在6.6%~24.9%之间,平均为15.6%;穗肥阶段(穗肥后到成熟)基本不再吸收基肥。基肥氮的总体恢复利用效率不高,在9.1%~22.8%之间,品种及氮肥运筹对基肥氮的总体恢复利用效率影响不显著。蘖肥主要在蘖肥阶段发生作用,施穗肥后水稻基本不再吸收蘖肥。蘖肥的总体恢复吸收利用率和基肥相当,在17%~34%之间,Y两优2号高于武运粳23。穗肥的回收效率最高,在54.0%~82.1%之间,武运粳23低于Y两优2号。水稻在整个生育期的总体氮肥恢复效率随氮肥用量的增加而下降,变化在32%~64%之间。水稻一生中吸收积累的氮素中,基肥的贡献占4.13%~10.59%(平均6.92%),蘖肥占3.98%~11.75%(平均7.58%),穗肥占13.32%~37.56%(平均26.02%),土壤的贡献在45.71%~70.83%(平均59.91%)之间。基蘖肥用量越大,其损失也越大,总体氮肥利用率也越低。研究结果证明,在水稻氮肥管理中必须考虑水稻各阶段对不同时期施肥的吸收利用情况,从而提高水稻氮肥利用效率,保证产量的同时减少不必要的损失。     

Technical efficiency of different farm sizes for tilapia farming in China

China is the world's largest tilapia producer. This study uses the stochastic frontier function in the Cobb–Douglas model to evaluate a production frontier for tilapia aquaculture and analyses the relationship between farm size and production efficiency in China. A random sample of 300 tilapia farmers was surveyed in the main tilapia‐producing areas to study their economic efficiencies. The percentage distribution of tilapia farm technical efficiency was determined, with an average efficiency of 79%, which showed that the sample tilapia farmers operate at 21% below the production frontier and hence that they still have a chance to achieve targeted yields. The technical efficiencies of two categories (≤1 ha and >1 ha) were 78.82% and 79.27% respectively. A second‐stage analysis investigated the relationship between farm size and technical efficiency and showed a positive relationship between farm size and production efficiency based on the ordinary least‐squares model. The optimal farm size was found to be 7.50 ha. This study proposes strategies such as enlarging the farming scale moderately, thereby achieving the advantage of economies of scale, and enhancing the competitiveness of the tilapia industry in China.     

Identification of sorghum genotypes suitable for specific end uses: Semolina recovery and popping

There has always been an interest in devising breeding programs for designer foods that would benefit both the producer and consumer. The challenge today is transformation of agriculture from “subsistence farming” to “market and income generation oriented” production system for which sorghum with its diverse end uses can assume significant role. Breeding for end-use identity-specific genotypes is needed for increased profitability to the farmers. In the present study, 60 sorghum genotypes were evaluated over two years to identify genotypes suitable for semolina recovery and popping properties, i.e. popping efficiency and pop volume expansion. Semolina recovery ranged from 20.7% to 48.3%, while popping efficiency ranged from 0 to 77.5%. Semolina recovery had positive and significant association with endosperm texture (r = 0.62), grain density (r = 0.49) and grain hardness (r = 0.55) indicating that genotypes with corneous endosperm yield high semolina. Also, semolina recovery had significant positive correlation with popping efficiency (r = 0.49) indicating that genotypes suitable for semolina can also be used for popping. Genetic divergence studies indicated that out of three clusters formed, cluster II having guinea race germplasm lines are suitable for semolina and popping. The information generated and the genotypes identified will help in enhancing the demand for sorghum as an industrial crop.     

玉屏风多糖脂质体的制备及表征研究

优选玉屏风多糖脂质体的最佳工艺并对其进行表征验证。采用逆向蒸发法制备玉屏风多糖脂质体,以膜材比、脂药比和超声时间为考察因素,包封率为评价指标,采用L9(34)正交试验设计优选制备条件,以超速离心法测定包封率,体外释药试验验证,纳米颗粒分析仪和透射电镜测定其粒径大小与形态。制备玉屏风多糖脂质体的最佳工艺为膜材比8∶1,脂药比4∶1,超声时间90s,包封率88.38%,24h累积释放率73.45%,平均粒径132.65nm。制备的玉屏风多糖脂质体具有较高的包封率与良好的缓释作用,粒径和形态较均匀,重现性好。     

膨化血粉饲喂生长犬的效果试验

选择健康的2月龄生长犬40只，随机分为3个试验组(A，B，C)和1个对照组(D)，试验组分别饲喂添加5％，10％和15％膨化血粉的复合饲料，对照组饲喂添加8％鱼粉的复合饲料，进行30d饲哏试验。试验结果表明：A，B，C组与时照组相比日增重分别提高18．97％，2．17％和-13．55％；肉料比降低了19．62％，6．19％和-7．69％。     

兽药二维码印刷及识读效率的研究

从国家兽药产品追溯系统中兽药二维码着手,针对兽药二维码印刷及识读效率方面的问题,对兽药二维码印刷方式、规格以及编码方式进行了分析与研究,提出了编码规则选择的依据、印刷规格的建议及其与识读效率间的关系,以期为兽药生产企业在实际应用中提高兽药二维码识读效率提供参考。     

几种杀虫剂对香蕉花蓟马的田间防治试验

选用60 g/L乙基多杀菌素悬浮剂、5%啶虫脒乳油、480 g/L毒死蜱乳油、450 g/L吡虫啉微乳剂、240 g/L螺虫乙酯悬浮剂、1%甲氨基阿维菌素苯甲酸盐乳油和200 g/L氯虫苯甲酰胺悬浮剂等7种杀虫剂对香蕉花蓟马进行了田间防治试验。结果表明: 当采用每间隔两天施药时,7种供试药剂对香蕉花蓟马都具一定的防治效果,其中以240 g/L螺虫乙酯悬浮剂0.25ml/L对该虫的防效最高,为87.92%,其次为60 g/L乙基多杀菌素悬浮剂0.67 ml/L,其防效为86.02%,再次是450 g/L吡虫啉微乳剂0.33 ml/L,防效为72.00%;5%啶虫脒乳油0.67ml/L、200 g/L氯虫苯甲酰胺悬浮剂0.33 ml/L、480 g/L毒死蜱乳油0.5 ml/L、1%甲氨基阿维菌素苯甲酸盐乳油0.33 ml/L对该虫的防效分别为：62.63%、54.48%、51.47%和45.91%,显著低于240 g/L螺虫乙酯悬浮剂和60 g/L乙基多杀菌素悬浮剂。     

脂质体介导法转染体细胞效率的优化

为建立脂质体介导的高效体细胞转染体系,采用脂质体TransfastTM包裹编码增强型绿色荧光蛋白(EGFP)的pCMV-EGFP质粒,转染5～13代山羊胎儿成纤维细胞,并用流式细胞仪检测不同DNA剂量、细胞汇合度、血清、转染时间及脂质体与DNA比例等参数对转染效率的影响。实验发现0.75μgDNA按1∶1的脂质体与DNA比例,在无血清条件下转染汇合50%细胞3h,转染效率最高可达40.7%±5%。4h转染时间、细胞汇合80%及转染体系中有血清会降低转染效率。随着DNA剂量的增加,转染效率呈剂量依赖性增高,但山羊成纤维细胞的活细胞数显著下降。实验表明TransfastTM能高效安全地介导外源基因转染山羊成纤维细胞。     

旋壳转速对腔内液体流动特性的效应

为研究旋壳转速对腔内液体流动特性的影响,以试验旋喷泵为研究对象,在高度验证叶轮与旋壳同步旋转试验与模拟结果准确性的基础上,对叶轮转速相同、旋壳转速不同的5个模型采用RNG k-ε湍流模型进行数值计算,分析腔内液体流动特性的变化情况,研究泵的性能.结果表明:旋壳转速增大,液体圆周速度和旋转系数均增大,圆周速度曲线沿径向逐渐形成同心圆,腔内液体做非刚性旋转.腔内液体径向压力梯度增大,压力低于624 kPa时,旋壳转速越高,压力越小;压力高于624 kPa时,旋壳转速越高,压力越大.集流管迎流区涡分布在进口附近,尾迹区涡集中在扩散段结尾处,整体呈增大趋势.旋壳转速增大,泵的扬程升高,但效率降低,通过改变集流管进口直径发现集流管并非效率降低的主要原因,而是由圆盘摩擦损失的增大导致的,圆盘摩擦损失随旋壳转速增加呈3次幂函数式增大,文中最优进口直径为13 mm.     

施氮量对不同水稻品种氮肥利用率与农艺性状的影响

为探明施氮量对不同水稻品种产量、氮肥利用率和农艺性状的影响,以适合江苏省种植的12个中粳稻（含籼/粳杂交稻）品种为材料,大田种植,设置0N（全生育期不施氮）、200N（全生育期施纯氮200kg/hm ²）和360N（全生育期施纯氮360kg/hm²）3个施氮量处理,研究各品种产量、氮肥利用率和一些农艺性状的差异。结果表明：甬优2640在3个施氮水平产量均最高,库容量大是其高产的主要原因。其他品种产量对氮肥响应的表现不一。在较低氮（0N、200N）条件下,淮稻13号和武运粳30的产量较高,宁粳1号和扬粳4038的产量较低。在高氮（360N）条件下,宁粳1号和扬粳4038产量较高。在较低施氮量条件下,产量和氮肥利用率较高的品种具有较高的干物质积累量、茎蘖成穗率、叶面积指数、粒叶比及群体生长速率,这些指标可作为筛选氮高效品种的农艺性状指标。