Observations on egg-laying behaviour of the banana weevil,Cosmopolites sordidus (Germar)

Banana weevil females laid on an average 2.7 eggs/week in rhizome material and 0.7 eggs/week in pseudostem material in the laboratory. At extremely high weevil population densities the egg-laying activity declined. Under controlled field conditions 0.7 eggs/week were laid in banana suckers and 1.3 eggs/week in stumps of harvested suckers. 25% of the weevil stages found in suckers in the field were eggs of which 78% were laid in the rhizome and 22% in the pseudostem base. The majority of eggs was deposited in the crown area of the rhizome followed by the remaining surface area of the rhizome, the walls of abandoned larval tunnels in rhizome and pseudostem and the leaf sheaths. 58% of the eggs found were considered accessible to egg predators.     

Different CMS sources found in Beta vulgaris ssp maritima: mitochondrial variability in wild populations revealed by a rapid screening procedure

Summary Mitochondrial DNA (mtDNA) variation in natural Beta maritima populations has been characterized by way of Southern blot hybridizations of total DNA using non-radioactive probes and chemiluminescent detection. It was found that the previously described N (normal) mitochondrial type could be subdivided into three subtypes. A new mitochondrial genotype (type R) was distinguished in addition to the previously described type S. Both are male-sterile cytoplasms and can produce a. segregation of sexual phenotypes in their progenies depending on the nuclear background. The populations contained at least two to four different mitochondrial genotypes.     

野芹菜体细胞胚胎发生早期变化的细胞学研究

通过光学与电子显微镜观察研究了野芹菜(Angelica polymorpha Maxim.)叶柄外植体胚性细胞的起源与原胚状体的发生。叶柄切段植入 MS 2mg/L2,4-D 0.25 mg/L KT固体培养基后,以DNA合成和细胞分裂为指标,判明了胚状体发生与紧贴维管束的鞘细胞层密切相关;鞘细胞通过有丝分裂形成多层结构的细胞群,它们仍含大液泡及薄层胞质,成片被覆在维管束表面;胚性细胞团即不同步地发生在该多层组织较内层的局部位点上,细胞具大核,胞质稠密,经持续有丝分裂发展成大小不同呈瘤状突起的原胚状体。伴随着鞘细胞的剧烈变化,韧皮部薄壁细胞亦分裂增殖,原有筛管变形衰退,部分新增殖的细胞分化为新筛分子;木质部中,原导管束附近朝向韧皮部一侧的部分薄壁细胞亦进一步分化为孔纹导管。外植体中维管系统的再次分化,显然是与输导功能强化以适应原胚状体发生时对营养物质的大量需求有关。     

香蕉林土壤可培养放线菌分离、鉴定及其抑菌活性

【背景】香蕉枯萎病是香蕉的顽固性疾病,制约着香蕉产业的发展,因此,筛选出对香蕉枯萎病菌(尖孢镰刀菌古巴专化型4号生理小种,简称Foc4)具有抑制活性的生防菌株具有重要意义。【目的】分离香蕉林土壤样品中放线菌并进行物种的初步鉴定,测定其对包括香蕉枯萎病致病菌的7种病原菌的拮抗活性,获得高活性菌株,以获得解决香蕉枯萎病的生物防治策略。【方法】采集多份广西地区香蕉林土壤样品,采用超声波等手段对其预处理,设置多种特异性培养基从中分离放线菌资源,对获得的放线菌进行基于16SrRNA基因序列的物种鉴定,以7种病原菌为靶标,采用平板对峙法从中筛选抑菌活性菌株,最后采用菌丝生长速率法对Foc4的抑菌率进行测定。【结果】从香蕉林土壤中分离出138株放线菌均为链霉菌,其中5株为潜在新种,分别为X1085、X1052、X2052、X3059和X4046;筛选出具有抑菌活性的菌株77株,阳性率为55.8%。20株对Foc4具有抑制活性,其中4株拮抗效果明显,抑制率大于80%,菌株X4050的抑菌率高达93.76%。【结论】初步明确了香蕉林土壤中可培养放线菌的物种信息,其中部分放线菌为未知物种,活性分析显示一半...     

Molecular and chromosomal evolution in anoas (Bovidae: Bubalus spec.)

As a contribution to their taxonomy, population genetic data on zoo-living anoas are reported, and a review of the history of the captive stock is provided. Four different chromosome numbers of 44, 45, 47 and 48 chromosomes have been found, respectively, when karyotyping captive anoas descending from three breeding lines. The number of chromosome arms is 60 throughout, indicating that Robertsonian rearrangements are responsible for this cytogenetic variation. An electrophoretic comparison of isozymes and blood proteins representing 21 genetic loci revealed polymorphism in seven loci: haemoglobin, glyoxalase, superoxide dismutase, phosphoglucomutase, carbonic anhydrase, glucose phosphate isomerase, and an unidentified acid serum protein. Considering the small number of founder specimens and subsequent inbreeding, allozyme variability appears fairly high in anoas. Genetic distances between zoo populations amount to 0.0505 or less. Southern blot hybridizations of restricted DNA from anoas and African buffaloes with a probe from the DRB-like region of the chimpanzee's MHC class II genes also indicate a low degree of genetic differentiation between mountain and lowland anoas. The relevance of these genetic data for the taxonomic classification of mountain and lowland anoas, and for the conservation of anoas by captive breeding is discussed.     

Adaptation to salinity inHordeum jubatum L. populations studied using reciprocal transplants

Tillers and seedlings ofHordeum jubatum L. from three sites with contrasting salinity regimes in central Saskatchewan, Canada were reciprocally transplanted in order to examine the tolerance of populations of this species to salinity and related habitat factors. Survival, growth and fecundity of the three populations were controlled more by transplant site characteristics than by genetic differences, i.e. differences among populations at a site tended to be smaller than differences among sites. Survival, growth and reproduction of all three populations were best at the non-saline site. The population originating at the non-saline site showed the poorest growth in the two saline habitats, but still had substantial salt tolerance. Fecundity was greatest when the populations were grow at their site of origin.     

Gathering and processing of lyme-grass (Elymus arenarius L.) in Iceland: an ethnohistorical account

Lyme-grass (Elymus arenarius L.) was harvested and processed for human consumption along the southern coast of Iceland until the beginning of this century. The origin of this exploitation is not known, but lyme-grass may have been gathered for this purpose already in the Viking Age. The system of processing lyme-grass is complex, and special implements and facilities are needed. The method is similar to traditional processing methods for cereals. Extensive research on Icelandic ethnographic observations was undertaken to establish the exact methods and sequence of operations that was involved. On the basis of this, a set of archaeological experiments was performed to test the viability of the processing techniques outlined in the written records. A model describing the harvesting and processing of lyme-grass is presented.     

检测香蕉花叶心腐病病原CMV的PAS—ELISA方法的改进

作为一种快速、敏感的免疫学方法,ELISA已被广泛地用于植物病毒的研究与应用性检测方面。在实验室中用PAS-ELISA检测香蕉花叶心腐病病原CMV已被证明是一种获得无CMV组培苗的有效手段。在香蕉无病毒组培苗工厂化大批量生产中,我们应用此法作为质量控制的手段之一,剔除病苗,保证产品不带CMV,获得一定成效。但同时我们也发现,香蕉组织中含有引起非特异性吸附反应的物     

Vegetation establishment on chalk marl spoil: the role of nurse grass species and fertiliser application

Abstract. The Channel Tunnel workings on the UK side have yielded nearly 4 million m³ of chalk-marl spoil which now forms a 36 ha landscaped reclamation platform. To establish vegetation of amenity and conservation interest on the spoil, seed mixtures of native wild flowers and grasses were sown with Lolium perenne (perennial rye grass) as a nurse species. Potentially, L. perenne is a suitable nurse species for grassland creation on infertile substrates as it provides rapid initial cover and stability, but it is non-persistent and declines in vigour with time, allowing wild flower species sown alongside to expand their cover and spread in the longer term. On very low fertility substrates like chalk marl, an initial application of fertilizer is needed to encourage plant growth. Results are reported of a fertilizer experiment on Channel Tunnel spoil to determine appropriate levels of fertilizer for establishment of species-rich grassland vegetation. An area hydroseeded with L. perenne and wild flowers in autumn 1992 was subjected to factorial treatment of four levels each of N and P in spring 1993. The results the following summer showed significant positive effects of nitrogen and phosphorus on L. perenne biomass and a negative impact of nitrogen on densities of wild flower species, especially legumes, establishing in the L. perenne sward. In general, low fertilizer applications encouraged low productivity and maximal species richness in the vegetation. Conversely high applications encouraged high productivity and competitive exclusion of sown wild flower species. Fertilizer applications must therefore balance encouragement of the stabilising nurse grass sward, while preventing competitive exclusion of wild flowers by the nurse grass.