中国花生制品国际市场势力分析

为了给我国花生制品贸易提供思路,利用剩余需求弹性模型,选取1991-2010年联合国FAOSTAT数据库、世界银行数据库中的花生制品贸易数据,实证检验了我国花生制品在韩国、日本、荷兰等国际市场的势力.结果表明:中国花生制品具备一定的国际市场势力,较低的生产成本和较高的国际市场份额有利于中国花生制品在国际市场中垄断势力的建立,而较低的国内花生制品市场集中度是导致中国花生制品出口价格较低的原因.并针对上述研究结果,提出了相应的对策建议.     

CO2浓度和抗药性对褐飞虱刺吸取食行为的影响

【目的】明确CO2浓度升高是否影响褐飞虱的取食行为以及抗药褐飞虱品系的刺吸行为是否与敏感品系存在差异,从而为预测CO2浓度升高条件下不同抗药性褐飞虱对水稻的致害性提供依据。【方法】采用刺吸电位技术（EPG）观察褐飞虱抗、感噻嗪酮品系（抗性水平相差约480倍）对当前（390 μL•L-1）和升高CO2浓度（780 μL•L-1）下生长水稻的口针刺吸行为,用双因素方差分析比较CO2浓度和抗药性2因素对口针刺吸显示的6种波形持续时间和频次的差异。【结果】CO2浓度加倍倾向于缩短感噻嗪酮褐飞虱在韧皮部摄取汁液的总时间,与抗药性互作显著影响开始刺探行为的频次：CO2浓度加倍条件下（780 μL•L-1）抗性褐飞虱开始刺探的频次低于当前CO2浓度下（390 μL•L-1）。抗噻嗪酮褐飞虱口针朝维管束移动和在木质部摄取汁液的时间延长,但在韧皮部内部活动的时间缩短;口针在韧皮部内部活动的频次增多,但在韧皮部和木质部摄取汁液的频次减少。【结论】抗噻嗪酮褐飞虱对水稻的致害性明显强于感噻嗪酮褐飞虱;CO2浓度升高可能使感噻嗪酮褐飞虱对水稻的致害性减弱,但对抗噻嗪酮褐飞虱没有显著影响。     

农药浓度、共代谢底物和接种量对Sphingobium indicum B90A降解六六六效率的影响

有机氯农药六六六曾被广泛用于卫生防疫和对抗农业病虫害,但由于其毒性和持久性引发了一系列环境问题。鉴于微生物降解方法在农药污染场地的修复中具有重要作用,采用摇瓶培养法研究了在α-、β-、γ-和δ-六六六（HCH）异构体混合体系中,农药浓度、共代谢底物和接种量对Sphingobium indicum B90A降解4种HCH异构体的影响。研究结果表明：S.indicum B90A对α-和β-HCH的利用较好,其次是γ-和δ-HCH。在10mg·L-1混合HCH的无机盐培养液中,30℃下反应72h,S.indicumB90A对α-、β-、γ-和δ-HCH的降解率分别为99%、86%、53%和33%。随着HCH浓度的增加,S.indicum B90A对4种HCH异构体降解率均逐渐降低。在共代谢底物的研究中,添加葡萄糖或酵母粉均能明显地提高S.indicumB90A对HCH的降解能力,在10mg·L-1混合无机盐培养液中,添加100mg·L-1葡萄糖或添加50mg·L-1酵母粉,30℃下反应84h,S.indicum B90A对α-、β-、γ-和δ-HCH的降解率均接近100%。S.indicum B90A对HCH的降解率随着菌体接种量的增加而相应提高,适宜接菌量为5%。     

Changes in soil bacterial community structure and microbial function caused by straw retention in the North China Plain

ABSTRACT

The effects of straw retention on soil bacterial community structure, microbial function, and biochemical properties were assessed. Terminal restriction fragment length polymorphism (T-RFLP) and community-level physiological profile (CLPP) assays were used to assess the bacteria community structure and microbial function respectively. Treatments included straw removal with conventional tillage (CT), straw retention with conventional tillage (SRCT) and straw retention with no tillage (SRNT). SRCT and SRNT significantly (p < 0.05) increased soil organic carbon by 8.9% and 9.7%, and microbial biomass carbon by 44.7% and 330.8%, respectively, compared with CT. T-RFLP analysis indicated that straw retention had no favourable effect on soil bacterial diversity, and SRCT significantly (p < 0.05) decreased bacterial diversity compared to CT. Among the three treatments, SRNT had the highest activity of urease, invertase, cellulase, and β-glucosidase. SRCT significantly (p < 0.05) increased the activity of invertase and β-glucosidase compared to CT treatment. CLPP analysis showed that microbial functional diversity was significantly (p < 0.05) increased by straw retention. Enzyme activity and microbial functional diversity were not correlated with bacterial diversity. Therefore, according to this study, SRNT is a better farming practice because it improves soil fertility and biological quality.     

Genomics‐informed design of loop‐mediated isothermal amplification for detection of phytopathogenic Xanthomonas arboricola pv. pruni at the intraspecific level

The objective of this study was to develop a rapid, sensitive detection assay for the quarantine pathogen Xanthomonas arboricola pv. pruni, causal agent of stone fruit bacterial spot, an economically important disease of Prunus spp. Unique targets were identified from X. arboricola pv. pruni genomes using a comparative genomics pipeline of other Xanthomonas species, subspecies and pathovars, and used to identify specific diagnostic markers. Loop‐mediated isothermal amplification (LAMP) was then applied to these markers to provide rapid, sensitive and specific detection. The method developed showed unrivalled specificity with the 79 tested strains and, in contrast to previously established techniques, distinguished between phylogenetically close subspecies such as X. arboricola pv. corylina. The sensitivity of this test is comparable to that of a previously reported TaqMan^? assay at 10³ CFU mL^?1, while the unrivalled speed of LAMP technology enables a positive result to be obtained in <15 min. The developed assay can be used with real‐time fluorescent detectors for quantitative results as well as with DNA‐staining dyes to function as a simplified strategy for on‐site pathogen detection.     

The significance of guttation in the secondary spread of Clavibacter michiganensis subsp. michiganensis in tomato greenhouses

Bacterial canker, caused by Clavibacter michiganensis subsp. michiganensis (Cmm), can spread in commercial tomato greenhouses causing epidemics. Results of greenhouse experiments with Cmm‐contaminated tools demonstrated disease spread for only a limited distance (<4 plants) from infected plants. However, touching symptomless infected plants bearing guttation droplets prior to touching nearby plants spread the pathogen over longer distances within rows (>22 plants). The pathogen was exuded in large numbers in the guttation fluid of infected plants; its presence in the guttation fluid was not influenced by the inoculation procedures, leaf age or the volume of the guttation droplets. Population size of Cmm and the incidence of leaflets with epiphytic bacteria were significantly higher in plants placed in a guttation‐induction chamber than in those kept in a growth chamber with high humidity, suggesting exudation through guttation contributed to the formation of epiphytic populations on leaflets. This new knowledge may provide a simple and environmentally friendly means for decreasing the spread of the disease by avoiding contact with plants during periods when they bear guttation droplets.     

The Provision and Subsequent Management of Plant Material for Herbicide Pot Experiments

Abstract

The marked resistance of Spodoptera spp. to endotoxins of Bacillus thuringiensis including the well recognized standards HD‐1–1971 and HD‐1‐S‐1980 has necessitated the search for a new active strain that can be used as a standard reference in the bioassays of these lepidopterous insects. The high activity of B. thuringiensis var. entomocidus HD‐635 vs. Spodoptera littoralis and S. exigua was found to fulfill these requirements. The sporeendotoxin complex of this strain, designated as HD‐635‐S‐1987, is proposed as a reference standard for bioassays against Spodoptera spp. and is assigned arbitrarily the value of 10,000 iu/mg. Potencies of an active strain, i.e. B. thuringiensis var. aizawai HD‐133 and of a low‐active preparation, i.e. HD‐1‐S‐1980 were carried out in reference to the newly proposed standard. Comparative studies revealed the possible reduction of bioassay period to 4 days as time saving and for a priori judgement on the activity of certain bioinsecticide preparations derived from B. thuringiensis.     

不同激素处理对假酸浆种子萌发的影响

【目的】假酸浆因种子外被胶质严重影响种子的萌发,探究不同处理对假酸浆种子萌发的影响,增加其种子的萌发率。【方法】以假酸浆种子为试材,采用随机区组法,设置种子放置在纱布上 4 ℃低温处理,以及赤霉素（GA3）、6- 苄氨基腺嘌呤（6-BA）和萘乙酸（NAA）的 MS 培养基处理,定期观察并作记录。【结果】与常温对照相比,种子放置在纱布上 4 ℃低温处理显著促进假酸浆种子萌发,以处理 48 h 发芽率最高为 25 个百分点。MS 培养基添加激素处理中,10 mg/L GA3 处理假酸浆种子发芽率和发芽指数分别为 92.00% 和9.58,比 CK 分别提高 4.27 个百分点和 1.33;1 mg/L 6-BA 处理假酸浆种子发芽率最高、为 96.63%,2 mg/L 6-BA处理发芽势最高、为 73.33%,比 CK 分别增加 8.9 个百分点和 10.07 个百分点;1、2 mg/L NAA 处理假酸浆种子发芽率均为 88.86%,但发芽势和发芽指数均比 CK 低;与 CK 相比,10、50 mg/L GA3 处理假酸浆种子下胚轴长度显著增加,而 6-BA 和 NAA 处理的下胚轴长度显著降低。【结论】低温处理能够显著促进假酸浆种子萌发,MS 培养基添加低浓度激素处理均能提高假酸浆种子的发芽率,通过发芽率、发芽势、发芽指数和下胚轴长度综合比较,假酸浆种子的最佳激素处理为 MS+10 mg/L GA3。     

发酵蓝莓酒品质影响因素及其解决方法

以"北陆"蓝莓为原料,研究果胶酶、护色单宁、酿酒酵母、二氧化硫和原酒冷冻浓缩对蓝莓酒品质的影响,探讨蓝莓酒中甲醇含量高、色素不稳定、有硫臭味、干浸出物含量低、感官品质差的解决方法,以提高蓝莓酒品质.结果表明,蓝莓果浆采用20 mg/L Clarification果胶酶酶解效果好,蓝莓酒中的甲醇含量低;采用浓缩汁发酵蓝莓酒,未检出甲醇,但原酒的典型性减弱;发酵前期加入500 mg/L护色单宁Tanin VR Supra,或陈酿期加入500 mg/L护色单宁Tanin VR Color,可有效提高蓝莓酒色素的稳定性;发酵结束后原酒中加入30 mg/L二氧化硫,既没有硫臭味,又能防止酒体氧化;8％原酒冷冻浓缩为10％原酒可提高干浸出物含量,增强其典型性;使用拉弗德F33酵母发酵酿造蓝莓酒,酒香浓郁,果香鲜明,酒体协调,蓝莓酒品质较优.     

不同类型土壤种植辣椒前后微生物多样性比较

旨在通过研究种植辣椒后的不同类型土壤根际微生物的群落结构变化特征,探索适合辣椒种植的微生物群落结构与土壤类型。以辣椒自交系SJ11-3为材料,利用Illumina MiSeq 2500测序平台对其种植前后不同类型土壤（包括潮土、稻田土和黄棕土）根际微生物进行测序和生物信息学分析,研究土壤细菌16S rRNA基因V3+V4区域和真菌ITS1区域的丰富度、多样性及微生物群落结构。结果表明,种植前土壤中共获得2253个细菌分类操作单元(OTU)和775个真菌OTU,种植后土壤中共获得2353个细菌OTU和877个真菌OTU。辣椒种植会使不同类型土壤中细菌和真菌的OTU数量有所上升,且潮土中特有的OTU在种植辣椒前后均明显高于稻田土和黄棕土。同时研究发现,辣椒种植后Rhodanobacter、Gemmatimonas、Bradyrhizobium、Sphingomonas等细菌和Fusarium、Penicillium等真菌在不同类型土壤中相对丰度均显著升高。另外群落物种丰富度指数（ACE和Chao1指数）和群落多样性指数（Shannon和Simpson指数）分析发现,种植辣椒会使潮土、稻田土和黄棕土中真菌Shannon指数显著升高,而Simpson指数显著降低,物种多样性显著上升;细菌多样性则无显著变化。种植辣椒对潮土、稻田土和黄棕土中微生物多样性的变化均会产生重要影响,改变土壤微生物的丰富度及OTU类型。潮土在种植辣椒后微生物群落结构较为健康,未发现有大量病原菌富集,但稻田土和黄棕土则更容易造成病原菌的富集,因此推荐潮土为辣椒种植的适宜土壤。