樱桃果蝇田间诱捕方法比较*

 通过田间试验，比较了糖醋液和香蕉气味对樱桃果蝇（Drosophila suzukii）的引诱效果。结果显示，5种（A，B，C，D，E）不同组份配比的糖醋液均以诱集雌虫为主，其中糖醋液B的效果最好。改变糖醋液中白酒与食用醋的比例对糖醋液诱集樱桃果蝇成虫的效果没有显著影响。香蕉气味对樱桃果蝇成虫表现出显著的引诱效果，所诱到的成虫性比超过6∶1。在诱捕器上加挂红色气球后可加强糖醋液对成虫的诱集效果，但不能显著改变所诱得的成虫雌雄比。     

The role of informal contracts in the growth of small cattle herds on the floodplains of the Lower Amazon

In the absence of access to formal credit, informal contracts with independent investors give the small ranchers of the Lower Amazon an acceptable means through which to surmount the high investment hurdle of starting a cattle herd. These contracts – called sociedades – allow small ranchers to raise an outside investor's cattle in return for a portion of the offspring and are commonplace in the cattle production systems of the Amazon. But, notwithstanding a vast literature on cattle production in the Amazon, informal contracts have been largely overlooked. This paper presents the results of a field survey and financial analysis for informal contracts on small ranches in the Lower Amazon. In the results, we suggest that informal contracts are an important means of cattle herd start-up and herd production for small ranchers. Internal rates of returns in cattle production under these contracts are in the range of –7 to –12% for the small rancher and 12% for the investor. The net present value of the contract to the small rancher ranges from –R$1219 to –R$8599 and from R$1681 to R$8845 for the investor, for a 10-year period, depending on herd size. Financial returns contracts are sensitive to the contract design – e.g., to who pays health costs – and to beef prices. The small ranchers have a negative IRR, lose money, and bear all the risk of loss, yet persist in using this form of herd development. We surmise that this is due to the non-financial benefits of cattle ownership and the lack of access to formal credit structures. In conclusion, although outside the formal economy and apparently financially unrewarding, these contracts are an important mechanism by which the small ranchers on the Amazon Floodplains create cattle herds.     

香蕉不同施肥试验研究初报

通过对河口地区连作多年香蕉园施肥试验,比较了不施氮、磷、钾肥对香蕉生长和产量的影响;根据土壤和植株营养测定数据,应用养分平衡法估算香蕉养分吸收量、土壤养分校正系数和肥料利用率等参数,为次年平衡配方施肥试验提供基础数据。     

不同苗龄“威廉斯B6”香蕉组培生根苗生产同批假植苗的研究

结合生根培养苗龄、假植基质等因素,研究了不同假植基质对不同苗龄香蕉组培生根苗假植成活率以及对假植苗假茎高度、叶片数、根系数、根系长度等生长指标的影响;同时研究了不同苗龄的瓶苗于不同季节在椰糠+珍珠岩中假植成活率的变化情况。结果表明:相同苗龄的香蕉组培生根苗在不同基质中假植成活率有显著差异,在椰糠+珍珠岩的混合基质中假植成活率最高;不同苗龄也是如此;结合假茎高度、叶片数、根系数、根系长度等生长指标认为椰糠+珍珠岩为最优假植基质,在这一基质中假植成活率可达92%～99%,能够满足不同苗龄香蕉组培生根苗在不同季节对假植基质的要求。     

超高效液相色谱-串联质谱法测定香蕉中壬基酚聚氧乙烯醚及其降解产物

为了研究壬基酚聚氧乙烯醚在食品中的残留量及安全性,通过乙腈提取、固相萃取法净化,建立了香蕉中壬基酚聚氧乙烯醚(NPnEO)及其降解产物壬基酚(NP)的超高效液相色谱-串联质谱(UPLC-MS/MS)测定方法,并对流动相、监测离子和校正曲线等进行了优化和探讨。结果表明:在5~40 μ g/kg添加水平范围内,NPnEO及NP的添加回收率在75%~117%之间,相对标准偏差(RSD)在3.2%~9.6%之间;NPnEO的检出限在0.005~0.04 μ g/kg之间,NP的检出限(LOD)为0.5 μ g/kg;该方法快速、灵敏,准确度高,符合残留检测的要求。     

中国热带地区不同作物长期轮作对土壤线虫群落结构及多样性的影响

A field experiment was carried out from 2003 to 2013 in the Wanzhong Farm of the Hainan Island, China, to determine the effects of two long-term banana rotations on the abundance and trophic groups of soil nematode communities in the island. The experiment was set out as a randomized complete block design with three replications of three treatments: banana-pineapple rotation(AB), banana-papaya rotation(BB) and banana monoculture(CK) in a conventional tillage system. Soil samples were taken at depths of 0–10, 10–20 and 20–30 cm, and nematodes were extracted by a modified cotton-wool filter method and identified to the genus level. Nematode ecological indices of Shannon-Weaver diversity(H′), dominance index(λ), maturity index(MI), plant parasite index(PPI), structure index(SI), enrichment index(EI), and channel index(CI) were calculated. A total of 28 nematode genera with relative abundance over 0.1% were identified, among which Tylenchus and Paratylenchus in the AB, Thonus in the BB, Tylenchus and Helicotylenchus in the CK were the dominant genera. The rotation soils favored bacterivores, fungivores and omnivores-predators with high colonizer-persister(c-p) values. Soil food web in the rotation systems was highly structured, mature and enriched as indicated by SI, MI and EI values, respectively. Higher abundance of bacterivores and lower values of CI suggested that the soil food web was dominated by a bacterial decomposition pathway in rotation soils. Nematode diversity was much higher after a decade of rotation.Soil depth had significant effects on the abundance of soil nematodes, but only on two nematode ecological indices(λ and MI).     

耐低钾香蕉基因型筛选指标的研究

通过砂培盆栽试验与田间缺钾(速效钾含量为95.2 mg/kg)试验,对香蕉苗期耐低钾基因型的筛选指标进行研究.结果显示,低钾条件下的地上部绝对生物量与相对生物量(0.025/2.50)、钾积累量和钾利用指数KUI极显著相关;砂培条件下9叶期幼苗的地上部绝对生物量、相对生物量和钾利用指数与田间产量呈著正相关.研究表明,以香蕉苗期地上部相对和绝对生物量、钾利用指数和吸钾量作为指标筛选耐低钾香蕉基因型是一条行之有效的途径.     

香蕉MYB转录因子基因的电子克隆及生物信息学分析

采用电子克隆方法获得香蕉MYB基因.通过生物信息学方法,对此序列编码的蛋白质从氨基酸组成、理化性质、疏水性/亲水性、结构域及其空间结构等方面进行了预测和分析.结果表明:香蕉MYB基因编码序列全长1 266 bp,包含1 266 bp的开放阅读框,编码413个氨基酸,含有1个保守的MYB功能域、1个SANT保守结构域.在序列组成、理化性质、结构域及空间构象等方面,与小麦等其他植物的MYB转录因子具有高度的相似性.     

二氧化氯对香蕉枯萎病菌和细菌性软腐病菌的消毒效果研究

研究不同浓度二氧化氯(ClO2)对土壤和水体中香蕉枯萎病菌小型分生孢子和水体中香蕉细菌性软腐病菌的杀灭效果,为控制香蕉枯萎病和软腐病的传播提供依据.通过统计分析消毒前后镰刀菌孢子和细菌的数量发现:3 mg/L以上ClO2可将待测镰刀菌孢子100％杀灭;20mg/L的ClO2淹土不能100％杀死土样中的镰刀菌孢子;800 mg/L以上ClO2浇灌粉蕉根系周边的土壤可有效减少镰刀菌数量,高于1 500mg/L ClO2消毒液可将土壤中镰刀菌100％杀灭.二氧化氯消毒显著降低土壤中细菌的数量,显著增加土壤真菌的数量,并明显减少土壤细菌和真菌的种类.5 mg/L的ClO2可将水体中香蕉细菌性软腐病菌100％杀灭.研究结果表明,高于5 mg/L的ClO2进行水体消毒可有效预防枯萎病和软腐病通过水源传播,对发病蕉穴土壤的消毒可以使用1 500 mg/L以上的C]O2处理以达到清除病原的目的.     

海南香蕉花叶病病毒分离物的研究

对海南产区感染花叶病的香蕉病株进行生物学分离获得一种直径为28—30nm的球形病毒分离物,该分离物汁液接种可引起香蕉花叶症状,并侵染一些黄瓜花叶病毒(CMV)的诊断寄主植物,提纯病毒外壳蛋白由一种分子量约为3.2×10~6道尔顿的亚基构成,琼脂免疫双扩散试验表明,该病毒分离物和CMV有血清学关系,根据这些性质该病毒分离物被鉴定为黄瓜花叶病毒。