异色瓢虫对胡萝卜微管蚜防治潜能评价

为明确异色瓢虫对胡萝卜微管蚜的防治效果潜能,本试验以芹菜为寄主植物,研究了异色瓢虫4龄幼虫对胡萝卜微管蚜捕食功能反应和不同益害比的控害效果.结果表明胡萝卜微管蚜密度为40、80、120(头)时,异色瓢虫的捕食量成增大趋势且各组之间有显著性差异,当胡萝卜微管蚜的密度为160、200、240(头)时瓢虫的捕食量各组间无显著性差异.4龄异色瓢虫幼虫的取食量受胡萝卜微管蚜密度影响显著,且捕食功能反应符合Holling-Ⅱ型反应模型.4龄异色瓢虫幼虫的瞬时攻击率a'为1.1862,取食1头胡萝卜微管蚜所需时间(即处置时间Th)为0.004,4龄异色瓢虫幼虫对胡萝卜微管蚜的最大捕食量为210.9头,瓢虫对蚜虫的搜索效应S=1+0.00474 N.益害比试验中得出4龄异色瓢虫幼虫对胡萝卜微管蚜捕食量符合二次回归方程,二次回归方程显示当胡萝卜微管蚜密度均为500时,随着异色瓢虫数量的增加,其捕食量成先增大后减少趋势,根据公式其最大捕食量为186.26,最佳益害比例为1∶83.本试验对利用异色瓢虫防治胡萝卜微管蚜具有一定的指导意义,以期为无公害芹菜种植提供有效的生物防治对策.     

氮素形态对植物生长影响的研究进展

铵态氮和硝态氮作为植物从土壤中吸收的主要无机态氮素,对植物的形态学特征以及生理过程具有不同的影响。从植物对不同形态氮素的吸收利用机制,氮素形态调控植物养分吸收、根系发育、光合生理、产量与品质形成及氮转运蛋白基因表达等方面进行了综述,阐述了氮素形态调控植物生长的机理,并提出了氮素形态研究中需要进一步阐明的问题。     

基于Panel Nerlove模型的我国牛肉供给反应实证分析

从牛肉供给的角度出发,依据2000-2012年全国29个地区的数据,采用Panel Nerlove经典模型及扩展模型,对我国牛肉市场的供给反应进行分析。结果表明,牛肉的短期供给弹性为0.171,长期供给弹性为0.615,小于1,是缺乏弹性的畜产品;滞后一期牛肉产量、滞后二期牛肉产量、滞后一期牛肉价格、羊肉价格对牛肉产量都有显著的影响。剖析了我国牛肉价格缺乏弹性的原因,并且基于此结论,提出一些发展我国肉牛产业的建议：国家应该在贸易谈判过程中有意识的保护国内肉牛产业,重点要扶持能繁母牛的养殖,重视国内饲草资源的开发和利用。     

Effects of long-term full straw return on yield and potassium response in wheat-maize rotation

The effect of long-term straw return on crop yield, soil potassium(K) content, soil organic matter, and crop response to K from both straw and chemical K fertilizer(K_2SO_4) were investigated in a fixed site field experiment for winter wheat-summer maize rotation in 6 years for 12 seasons. The field experiment was located in northern part of North China Plain with a sandy soil in relatively low yield potential. Two factors, straw return and chemical K fertilizer, were studied with two levels in each factor. Field split design was employed, with two straw treatments, full straw return of previous crop(St) and no straw return, in main plots, and two chemical K fertilizer treatments, 0 and 60 kg K2 O ha~(–1), as sub-plots. The results showed that straw return significantly increased yields of winter wheat and summer maize by 16.5 and 13.2% in average, respectively, and the positive effect of straw return to crop yield showed more effective in lower yield season. Straw return significantly increased K absorption by the crops, with significant increase in straw part. In treatment with straw return, the K content in crop straw increased by 15.9 and 21.8% in wheat and maize, respectively, compared with no straw return treatment. But, straw return had little effect on K content in grain of the crops. Straw return had significant influences on total K uptake by wheat and maize plants, with an increase of 32.7 and 30.9%, respectively. There was a significant correlation between crop yield and K uptake by the plant. To produce 100 kg grain, the wheat and maize plants absorbed 3.26 and 2.24 kg K2 O, respectively. The contents of soil available K and soil organic matter were significantly affected by the straw return with an increase of 6.07 and 23.0%, respectively, compared to no straw return treatment. K_2SO_4 application in rate of 60 kg K2 O ha~(–1) showed no significant effect on wheat and maize yield, K content in crop straw, total K uptake by the crops, soil available K content, and soil organic matter. The apparent K utilization rate(percentage of applied K absorbed by the crop in the season) showed difference for wheat and maize with different K sources. In wheat season, the K utilization rate from K_2SO_4 was higher than that from straw, while in maize season, the K utilization rate from straw was higher than that from chemical fertilizer. In the whole wheat-maize rotation system, the K absorption efficiency by the two crops from straw was higher than that from K_2SO_4.     

伊维菌素纳米乳透皮制剂的研究

本试验研制伊维菌素纳米乳透皮制剂,并对其理化性能、稳定性、体外药物释放及透皮性能进行评价。采用三元相图筛选不同载药量的纳米乳,确定最佳载药量;采用响应面优化设计筛选纳米乳处方,考察了伊维菌素纳米乳的平均粒径、电位、形态、pH、黏度等性能;分别采用透析袋法和Franz扩散池法比较伊维菌素纳米乳透皮制剂与市售伊维菌素皮肤涂剂的体外释放行为和透皮性能。结果显示,载药量为2.00%时,纳米乳区域最大、最稳定;获得的优选处方为聚氧乙烯蓖麻油 :二乙二醇单乙基醚 :油酸乙酯 :伊维菌素 :水=26 :12 :7: 2: 53;所得伊维菌素纳米乳的平均粒径为18 nm;伊维菌素纳米乳在室温条件和4 ℃冰箱中保存1年仍稳定;其24 h皮肤累积渗透量和滞留量分别是市售伊维菌素皮肤涂剂的3.24和2.05倍。研究结果表明,研制的新型伊维菌素纳米乳透皮制剂具有制备工艺简便、稳定性好、透皮性能好等优点,具有很好的应用前景。     

Estimates of the leaf area of forage peanut for use in morphogenetic assessment

Understanding the morpho-physiological responses of forage plants is critical for successfully managing pastures; however, there is no specific method for morphogenetically assessing Arachis pintoi. The present study aimed to develop and validate mathematical models to estimate leaf area in A. pintoi to enable assessments of leaf elongation and senescence. Two experiments were performed. The first experiment used 500 A. pintoi leaves to model leaf area. Three models were used: correlation, mechanistic and empirical. A total of 336 leaflets were collected to validate the models. For the second experiment, 786 leaflet pairs were collected to test the leaf symmetry. Leaf length (L), width (W) and area (A) were measured for each leaflet in both of the experiments. The model identity test was used. The leaflet area can be estimated using the following formula:  = W ×L × 0·25 × π. Experiment 2 showed that the initial leaflet pairs were equal, as were the terminal leaflet pairs. In conclusion, the mechanistic model should be used to estimate the leaf area for A. pintoi, and only half of each leaf can be measured.     

Comparative Feeding Performance and Digestive Physiology of Helicoverpa armigera (Lepidoptera: Noctuidae) Larvae-Fed 11 Corn Hybrids

This study aimed to evaluate the feeding responses and digestive proteolytic and amylolytic activity of Helicoverpa armigera (Hübner) on 11 corn (Zea mays L.) hybrids at 25 ± 1°C, 65 ± 5% relative humidity (RH), and a photoperiod of 16:8 (L:D) h. The fourth- and fifth-instar larvae fed on hybrid K47*K19 had the highest weight of food consumption and those reared on hybrid KSC705 had the lowest value of food consumption. The highest weight gain of the larvae was observed when H. armigera were fed hybrid KLM78*MO17 and lowest when they were fed hybrids K36 * MO17, KSC705, and K35 * K36. Pupal weight of H. armigera was heaviest when larvae were fed hybrid K47*K19 and lightest when they were fed hybrid KSC705. The highest proteolytic activity of the fourth-instar larvae was observed when they were fed hybrid KSC705, and the lowest activity was observed when they were fed hybrid K47*A67. Fifth-instar larvae that fed on hybrid K47*K19 showed the highest proteolytic activity. Fourth-instar larvae that fed on hybrid K36*MO17 showed the highest amylase activity. The fifth-instar larvae fed on hybrid K47*A67 showed the maximum amylase activity and those reared on the K48*K18 showed the minimum activity. Our results indicated that K36 * MO17, KSC705, and K48 * K18 were the most unsuitable hybrids for feeding H. armigera.     

4种燕麦对NaCl胁迫的生理响应及耐盐性评价

为研究4份燕麦坝莜一号、白燕2号、白燕6号和白燕7号的耐盐程度及其在盐胁迫处理下的生理反应规律,在水培条件下,分别用0,34.2,68.4,102.6,136.8,171.0 mmol/L浓度NaCl溶液模拟盐胁迫处理4种燕麦种子,观察记录各处理的盐害情况,分别测定了胁迫后的种子发芽势、发芽率、株高和根长,以及室温培养的燕麦幼苗叶片过氧化物酶(POD)、超氧化物歧化酶(SOD)和可溶性蛋白含量,分析了不同胁迫程度下各生理指标的变化情况,并且对4种燕麦的耐盐性进行了综合评价。结果表明,NaCl胁迫对4种燕麦种子的发芽势和发芽率均产生显著影响,对株高和根长产生了抑制作用,且均随盐浓度的增大呈逐渐降低的趋势;燕麦幼苗叶片POD活性、SOD活性、可溶性蛋白含量均在102.6 mmol/L 盐浓度下达到最大值,而且都随盐浓度的增大呈先升高后降低的趋势,表明燕麦具有较高的耐盐能力,在盐胁迫下可采取自我保护机制以适应盐胁迫,4种燕麦的耐盐阈值为102.6 mmol/L盐浓度。综合评价,白燕6号耐盐性较好,白燕2号具有高盐耐受性的潜力,这两个燕麦品种可以为耐盐基因挖掘及燕麦耐盐品种的选育提供材料。     

不同佐剂对大鲵嗜水气单胞菌灭活疫苗的免疫效果

为了探究添加蜂胶佐剂、弗氏佐剂和铝胶佐剂后对大鲵（Andrias davidianus）嗜水气单胞菌（Aeromonas hydrophila）灭活疫苗的免疫效果,取已制备好的大鲵嗜水气单胞菌灭活疫苗,分别加入3种佐剂,充分混匀后制备成含菌量为1×108 CFU/mL的佐剂疫苗,通过腹腔注射免疫健康大鲵(平均体长40 cm、平均体质量85 g）,每尾1 mL,并设不加佐剂组和对照组;分别于免疫后第1、4、7、14、21、28、35天尾静脉采血,利用凝集反应检测血清抗体效价,于免疫后第35天进行攻毒感染试验。结果表明,与对照组相比,蜂胶佐剂组抗体效价于免疫后第1～14天呈上升趋势,第21天达最高,为1: 469.33,弗氏佐剂组于免疫后第1～28天呈上升趋势,第35天达到最大值,为1: 448.00,随后呈下降趋势;铝胶佐剂组抗体效价于免疫后第1～21天呈上升趋势,第28天达到最大值,为1: 362.67,不加佐剂组于免疫后第21天达最高,为1: 384.00,随后呈下降趋势,而对照组基本稳定在1:4.00。攻毒感染试验表明,蜂胶佐剂组、弗氏佐剂组、铝胶佐剂组和不加佐剂组的死亡率为10%、20%、25%和35%,相对免疫保护率分别为88.9%、77.8%、72.2%和61.1%,对照组大鲵死亡率为90%;3种佐剂疫苗均有较好的免疫保护效果,其中以蜂胶佐剂疫苗效果最佳。     

Modelling the food web for assessment of the impact of stock supplementation in a reservoir ecosystem in India

Comparative estimates of trophic status and energy flow were carried out in a tropical reservoir ecosystem in India to assess the impact of fish stocking. Mass‐balanced models of the reservoir ecosystem were constructed for two periods – 1982–1983 and 2002–2003 – using ecopath software to determine the impacts on different groups before and after stocking. Mixed trophic impact (MTI) analyses indicated that phytoplankton and detritus have a positive impact on most groups. There was a decrease in nutrient flow through the system from pre‐stocking to post‐stocking (22.28%). The baseline was higher by 0.29% in the post‐stock phase indicating maturity. The ecosystem indices tested indicate that the reservoir was in a more resilient state post‐stocking than during the pre‐stocking phase. The ‘health’ of the ecosystem showed an improvement, which indicates a positive impact of stocking.