Persistence over time,overlapping distribution and molecular indications of interspecific hybridization in wild potato populations of Northwest Argentina

Solanum gourlayi and Solanum spegazzinii, wild potatoes endemic to Argentina, possess desirable traits for breeding. In periodical regenerations of accessions, variability was detected for morphology and breeding barriers. The persistence of these populations in nature was evaluated after more than 20 years. Both species were observed in all visited sites, along with other wild and cultivated potatoes. Chromosome numbers coincided with the originally reported, except for one population of Solanum gourlayi, with diploid and tetraploid cytotypes. The accompanying flora and environmental conditions revealed important alterations as the result of road construction, excessive stocking rates and overgrazing. Principal coordinate and cluster analyses and an AMOVA using AFLP data of three original accessions and the corresponding new accessions revealed high molecular variability and extensive overlapping. Plant grouping of accessions occurred at a distance of 0.58 for S. gourlayi, 0.62 for S. spegazzinii and 0.67 for both species. The role of natural hybridization and sexual polyploidization in the evolution of sympatric populations of wild potatoes is discussed.

Unraveling the origin of <Emphasis Type="Italic">Coffea arabica</Emphasis> ‘Bourbon pointu’ from La Réunion: a historical and scientific perspective

Coffee is one of the main products on the international markets, in association with oil, corn, sugar, and paper pulp. The history of coffee-tree cultivation is incompletely documented, both regarding its domestication in Africa, and its assisted dispersal throughout the world. This review focuses on the coffee mutant, Coffea arabica ‘Laurina’ (Chevalier A in Encyclopedie Biologique. Vol 28, 1947), also named ‘Bourbon pointu’. This plant is generally acknowledged to have been selected in the island of ‘Bourbon’ (La Réunion) from a field at the beginning of the 19th century. Compared with the common ‘Bourbon’ variety, ‘Bourbon pointu’ trees are dwarf, with a characteristic Christmas-tree shape and the beans have an excellent cup quality. Although cited many times in literature, the origin of this variety is ambiguous and is largely discussed even today with increasing confusion, particularly in books and local newsletters. This article provides a thorough historical and bibliographical review of coffee cultivation in La Réunion, which leads to an understanding of the bottleneck responsible for the low genetic diversity of the ‘Bourbon’-type modern varieties. Complemented by a review of the scientific studies conducted on this subject, confirmation of the veracity of the various historical accounts becomes possible, and appropriate conclusions on the origin of the ‘Bourbon pointu’ are derived. Although historical texts provide important information and represent priceless resources that give direction to scientific research, it is clear that this same research makes it possible, in turn, to clarify and to interpret historical texts.

Evolution over 16 years in a bulk-hybrid population of subterranean clover (<Emphasis Type="Italic">Trifolium subterraneum</Emphasis> L.) at two contrasting sites in south-western Australia

Evolution was measured over 16 years in a self-regenerating, bulk-hybrid subterranean clover population, consisting of F ₂ seed from 253 crosses, sown at Nabawa and Mt Barker, short and long growing season sites, respectively, in south-western Australia. Seed bank samples harvested annually were grown in a common garden. Experiment 1 measured flowering time in plants from each year, while Experiment 2 measured 26 variables in the populations 3 and 16 years after sowing, in comparison with the ancestral population. Changes in population means were observed in 20 characters and variability declined in 11 characters at one or both sites, with much of this occurring within the first three years. Natural selection at Nabawa favoured early flowering of long duration, thick peduncles, high harvest index and high hardseededness. At Mt Barker it favoured late flowering of short duration, large leaves and long, thick petioles at flowering, thick stems with long internodes, long, thin peduncles with a high burial angle, large plants at maturity, low hardseededness and high biochanin A and total isoflavone contents. High seed production capacity, with high seed weight and seeds per burr, was important at both sites. The use of bulk-hybrid populations is demonstrated as a low-input means of breeding and selecting well-adapted subterranean clovers.

Multi-attribute responses of maize inbred lines across managed environments

In maize (Zea mays L.) breeding programs, selection among and within segregating progenies is based mainly on indirect selection criteria. A better understanding of the environment influence on physiological attributes of maize inbred lines is important to the identification and selection of superior inbred lines as well as to successful hybrid seed production. In this study, the size and form of genotype (G) and genotype × environment (G × E) interaction effects for plant grain yield (PGY) and several physiological attributes were examined for 12 maize inbred lines grown in four managed environments, represented by two seasons (Y) and two nitrogen levels. Mixed model analysis revealed that the G effect was relatively high for attributes related to light capture, phenology, early biomass production, and numerical components of PGY. The G × E interaction effect explained most of the variability for PGY, harvest index (HI), and biomass production at maturity. Three-mode principal component analysis allowed us to: (1) describe the associations among multiple attributes across environments, (2) reveal the form of the main patterns of G × E interaction, (3) establish the importance of the genotype × year (G × Y) interaction for kernel number, HI, and biomass at maturity in determining PGY, (4) identify promising genotypes of high-PGY across environments, and (5) detect genotypes of similar response patterns for PGY but with a contrasting relative behavior for other attributes, which may permit the simultaneous selection for grain yield and desired secondary traits. Such selection results would contribute greatly in the identification of superior inbreds than selecting for grain yield alone.

Changes in the concept of genotype × environment interactions to fit agriculture diversification and decentralized participatory plant breeding: pluridisciplinary point of view

The standardization of environments (E) encouraged by modern society and by the productivist model of agriculture has resulted in the standardization of genotypes (G) thereby reducing G × E interaction. New societal values call for the diversification of agriculture to fit contrasted environments. This process can be depicted by four models defined by two axes, one socio-economic (individual logics versus collective governance), and the other agro-ecological (reductionist versus systemic approaches). These models differ in (i) their objectives (from improvement in yield to the empowerment of farmers), (ii) their specific expectations with respect to genotypes (from inherited genetic resources to varieties that represent genetic, ethical and social progress), (iii) their specific representations of the environment (E) (from a simple interaction between the bio-physical environment (B) and the crop management (C), to a complex interaction including the competences of the actors (A), outlets (O), regulations (R), society (S)), (iv) their particular relations between G and E (from G × E to G × B × C × A under evolving constraints represented by R × O × S). Taking this diversity into account changes the way plant improvement is considered. Thus, depending on the model, the order, interest and status of the five classic stages of plant improvement (setting objectives, creating variability, selecting, evaluating and disseminating) may be called into question. Between the existing analytical model (Model I) and a holistic model (Model IV) which remains to be developed, lies the challenge of ensuring the sustainability, efficiency and acceptability of plant breeding and resulting innovations. From a simple “statistical parameter” that we, as plant breeders, attempt to reduce, the G × E interaction is becoming an “objective” that we try to predict and valorize. Structuring the different components of E, G and G × E, enables us to extend the basic concept of representivity to both the cultivation conditions and the relational socio-economic positions of the actors involved.

Returns to investment in new breeding technologies

Wheat breeding is an economic activity that has provided high returns on past investments. Recent developments include technologies that can lead to improved utilization of genetic resources, improved selection methods, more rapid fixed lines, improved statistical analysis, and improved targeting of production environments. They have the potential to allow for the development of new varieties more rapidly, and/or varieties with enhanced productivity in targeted environments, and varieties with novel characteristics. To ensure that future breeding investments also have high returns, breeding programs need to assess these new technologies to determine whether to incorporate them into their program. Clearly, given the extent of uptake by breeders, there are significant perceived gains from incorporating some of the new technologies. However, not all programs will want to invest in all the new technologies. This paper identifies the criteria needed to assess which technologies may be most gainfully utilized. In some cases, the technologies can lower costs for a given operation. In other cases, they allow the selection program to be restructured by providing additional information at an earlier stage of the program or by targeting specific traits. However, several of the new technologies require significant investment, either in the infrastructure itself if the operations will be conducted within the breeding organization, or funding for contracting if the operations are done by outside organizations. Access to these facilities and the size of the necessary investment can be important issues for breeders considering incorporating the new technologies in their programs. Where some significant gains can be achieved at relatively low cost, all programs can adopt the new technology. Where the investment is large, only select breeding programs will be able to afford to incorporate the new technology into their programs. Analysis of marker-assisted selection shows that some markers can enable some operations to be carried out at a fraction of the cost of phenotypic evaluation. Similarly, analysis of the stomatal aperture-related traits of leaf porosity and canopy temperature depression shows that both are low-cost options that can lead to significant cost savings in selecting for yield. If the resources saved with such technologies are reinvested in the program, the restructured programs are likely to produce markedly higher rates of gain from breeding, and consequently higher rates of return on the investment in wheat breeding.

Effect of two wheat genotypes and Swedish environment on falling number, amylase activities, and protein concentration and composition

Variation in falling number, amylase activities, protein concentration and composition were investigated in two wheat cultivars grown in Sweden over two seasons, in four locations, with four N fertilizer rates, with and without fungicide treatment. The results showed that;

Microsatellite (SSR) variation in a collection of Malus (apple) species and hybrids

A collection of 142 accessions of 23 Malus species, derived hybrids and cultivar accessions from the USDA-ARS Plant Genetic Resources Unit's core collection, which represents an extensive range of Malus species, was screened with a set of previously described SSR (simple sequence repeat) markers. The markers were used to determine genetic identities, estimate genetic diversity, identify genetic relationships among the accessions, and determine the utility of SSR primers developed from Malus ×domestica for making genetic assessments across the whole Malus genus. All eight primer pairs amplified multiple fragments when used in polymerase chain reactions with DNA from these accessions. High levels of variation were detected with a mean of 26.4 alleles per locus and a mean direct count heterozygosity across all eight loci equal to 0.623. The eight primer pairs used in this study unambiguously differentiated all but five pairs of accessions in this collection of 142 accessions of 23 Malus species, derived hybrids and cultivars. These SSR data were not useful in identifying genetic relationships among this diverse collection of accessions, with the majority of the accessions not clustering in ways concordant with taxonomic information and/or geographic origin. The resulting phenogram resolved only two meaningful clusters, for the taxonomically isolated Section Chloromeles and for M. fusca accessions, reflecting genetic relationships arising from geographic origin. The detection of identical accessions in the collection, which were previously considered to be unique, highlights the critical need to further bolster collections of certain Malus species. This revised version was published online in July 2006 with corrections to the Cover Date.     

Germplasm diversity and estimate of genetic advance of four morpho-physiological traits in a world collection of jute

Summary To improve jute productivity, locating of sources of suitable quantitative-trait genes in the recently acquired world jute collection was needed. Two hundred sixteen accessions of Corchorus capsularis and 192 accessions of C. olitorius were evaluated at a jute seed research station (87°60\s'E, 23°80\s'N) for four yield and quality linked morpho-physiological traits. The objectives were to estimate the germplasm diversity, phenotypic (PCV) and genetic (GCV) coefficients of variation, broad sense heritability (h²) and genetic advance (GA) with respect to origins and traits. Irrespective of origins all the traits showed more than 60–80% diversity in both species. Trait means of diversity were significant but not the origin means. Generally, only slightly higher PCV values than GCV were obtained for all the traits in both the species. High h² values ranging from 50% to more than 98% were also found. All the traits can be simultaneously utilized for genetic gain. Most of the C. olitorius accessions with two times higher GA estimates than those of the C. capsularis are likely to be more successful for that matter. Maximum genetic gain is expected from Mutants > China > Brazil > India > Thailand > Nepal > Burma in C. capsularis while from Thailand > Tanzania > Mutants > Kenya > Other countries in C. olitorius. C. capsularis mutants with high heterogenity for most of the traits should be useful for finding many rare alleles.     

Diploid and tetraploid progenitors of wheat are valuable sources of resistance to the root lesion nematode <Emphasis Type="Italic">Pratylenchus</Emphasis><Emphasis Type="Italic">thornei</Emphasis>

The root lesion nematode Pratylenchus thornei is widely distributed in Australian wheat (Triticum aestivum) producing regions and can reduce yield by more than 50%, costing the industry AU$50 M/year. Genetic resistance is the most effective form of management but no commercial cultivars are resistant (R) and the best parental lines are only moderately R. The wild relatives of wheat have evolved in P. thornei-infested soil for millennia and may have superior levels of resistance that can be transferred to commercial wheats. To evaluate this hypothesis, a collection of 251 accessions of wheat and related species was tested for resistance to P. thornei under controlled conditions in glasshouse pot experiments over two consecutive years. Diploid accessions were more R than tetraploid accessions which proved more R than hexaploid accessions. Of the diploid accessions, 11 (52%) Aegilops speltoides (S-[B]-genome), 10 (43%) Triticum monococcum (A ^m -genome) and 5 (24%) Triticum urartu (A ^u -genome) accessions were R. One tetraploid accession (Triticum dicoccoides) was R. This establishes for the first time that P. thornei resistance is located on the A-genome and confirms resistance on the B-genome. Since previous research has shown that the moderate levels of P. thornei resistance in hexaploid wheat are dose-dependent, additive and located on the B and D-genomes, it would seem efficient to target A-genome resistance for introduction to hexaploid lines through direct crossing, using durum wheat as a bridging species and/or through the development of amphiploids. This would allow resistances from each genome to be combined to generate a higher level of resistance than is currently available in hexaploid wheat.     

Morphological and biochemical variation in Sardinian populations ofMedicago polymorpha L. suitable for rainfed Mediterranean conditions

Summary Forty five accessions of Sardinian germplasm ofMedicago polymorpha L., derived from a wide range of climatic and edaphic conditions, were evaluated to identify useful genetic resources for the development of cultivars for rainfed Mediterranean conditions. The accessions were assessed for variation in morphological, agronomic and biochemical traits. Considerable variation was found between populations indicating the potential for selection.Work supported by the Italian Ministry of Agriculture and Forestry (MAF), Special Project Foraggicoltura Prativa, subproject Miglioramento Genetico.     

Penetrance of creeping-rootedness in clonal progenies of lucerne and observations on underground morphology of plants differing for this character

Elaeis oleifera or ‘caiaué’, a close relative of oil palm (E. guineensis), has some agronomic traits of great interest for the oil palm genetic breeding such as slow growth, oil quality (mostly unsaturated) and disease resistance. An analysis of a Brazilian oil palm germplasm collection was carried out using RAPD (Random Amplified Polymorphic DNA) markers with the objective of understanding the genetic variation of ‘caiaué’ accessions collected in the Amazon Forest in the last two decades. A sample of 175 accessions obtained along the Amazon River Basin was analyzed and compared to 17 accessions of oil palm from Africa. Ninety-six RAPD markers were used in the analysis, of which fourteen were shown to be specific to oil palm, while twelve were specific to ‘caiaué’. Results showed that the Brazilian ‘caiaué’ accessions studied have moderate levels of genetic diversity as compared to oil palm accessions. The data allowed the establishment of similarity groups for ‘caiaué’ accessions, which is useful for selecting parental plants for population breeding. Cluster analysis showed that, in general, genetic similarities are not correlated to geographical distances, but consistent with geographical dispersal along the Amazon River network. AMOVA showed that most of the genetic variation is found within populations, as expected for anallogamous and long-lived perennial species. The study provides important information to define strategies for future collection expeditions, for germplasm conservation and for the use of E. oleifera in breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterization, diversity, and relationships of the Spanish striped (Listada) eggplants: a model for the enhancement and protection of local heirlooms

Spanish striped eggplants (Solanum melongena L.) are generally known as Listada. Among them, the most internationally renowned is the Listada de Gandía heirloom. Enhancement and legal protection of these local materials requires the analysis of their characteristics, diversity and relationships with similar accessions. We performed a morphological, agronomic and molecular (amplified fragment length polymorphism; AFLP) characterization of 33 eggplant accessions, which included 20 Striped accessions, of which nine were Spanish (five Listada de Gandía and four of Other Spanish Listada), 11 non-Spanish (six of Non-Spanish Listada and five of Other Non-Spanish Striped) and 13 Non-Striped accessions. The Striped accessions presented a range of morphological, agronomic and genetic diversity comparable to the one observed in the Non-Striped accessions. Multivariate PCA (morphological) and PCoA (molecular) analyzes group together the Listada accessions, and clearly separate the three Listada subgroups (Listada de Gandía, Other Spanish Listada and Non-Spanish Listada). On the other hand, the Other Non-Spanish Striped accessions are closer to Non-Striped than to Listada accessions. Listada eggplants, as well as each of their subgroups, are characterized by a syndrome of morphological traits that allows distinguishing them from other accessions. Furthermore, AFLP markers which allow distinguishing Listada accessions and the Listada de Gandía heirloom have been found. The agronomic characterization shows that despite the low diversity within Listada de Gandía group, it is possible to select accessions with improved agronomic performance. The results obtained have important implications for the conservation, improvement and legal protection of Spanish striped eggplants, and in particular of the Listada de Gandía heirloom. The methodology and approaches used may provide a model for the enhancement and protection of other vegetable crops heirlooms.     

Establishment of Chinese soybean Glycine max core collections with agronomic traits and SSR markers

It is very important to efficiently study and use genetic diversity resources in crop breeding and sustainable agriculture. In this study, different sampling methods and sample sizes were compared in order to optimize the strategies for building a rationally sized core collection of Chinese soybean (Glycine max). The diversity in the core collection captured more than 70% of that in the pre-core collection, no matter what sampling methods were used, at a sampling proportion of 1%. Core collections established with both simple sequence repeat (SSR) marker data and agronomic traits were more representative than those chosen on an independent basis. An optimal sampling method for a soybean core collection was determined, in which strategy ‘S’ (allocating accessions to clusters according to the proportion of square root of the original sample size within each ecotype) was used based on SSR and agronomic data. Curve estimation was used to estimate the allelic richness of the entire Chinese soybean germplasm and a minimum sample size for a core collection, on which a sampling proportion of about 2% was determined to be optimal for a core collection. Further analysis on the core collection with fourteen agronomic traits and allelic constitution at 60 SSR loci suggested that it highly represented the entire collections both on genetic structure and diversity distribution. This core collection would provide an effective platform in proper exploitation of soybean germplasm resources for the study of complex traits and discovering important novel traits for crop genetic development.     

Analysis of meiotic behavior in selecting potential genitors among diploid and artificially induced tetraploid accessions of Brachiaria ruziziensis (Poaceae)

Sexuality is correlated with diploidy and apomixis with polyploidy in the Brachiaria genus. Brachiaria ruziziensis is a key species in Brachiaria breeding due to its obligate sexuality and intrinsic agronomic qualities. Interspecific crosses in the genus became feasible only when a few diploid accessions of B. ruziziensis were artificially tetraploidized and remained sexual. Hybridization has been done since, using natural tetraploid apomictic accessions of B. brizantha or B. decumbens as pollen donors. Twenty two accessions of B. ruziziensis from the Embrapa Beef Cattle germplasm collection (Campo Grande, MS, Brazil) were cytologically analyzed: 16 are natural diploids (2n = 2x = 18) and six are artificially induced tetraploids (2n = 4x = 36). The meiotic behavior in the 16 diploid accessions varied. The mean of meiotic abnormalities per accession ranged from zero to 24.46%. Meiotic behavior in the induced tetraploid accessions also varied with the mean of meiotic abnormalities ranging from 5.20% to 54.71%. The most common abnormalities observed in both the diploid and the tetraploid accessions, were those related to irregular chromosome segregation. In one tetraploid accession, with a high frequency of those, other irregularities involving chromosome orientation at metaphase plate and chromosome convergence to the poles, a meiotic mutation known as divergent spindle, were recorded. Meiotic behavior should be considered in selecting potential genitors for breeding.     

DNA profiling and genetic diversity of Korean soybean (<Emphasis Type="Italic">Glycine max</Emphasis> (L.) Merrill) landraces by SSR markers

Approximately 7,000 accessions of Korean soybean (Glycine max (L.) Merrill) landraces, largely composed of three collections, the Korea Atomic Energy Research Institute’s soybean (KAS), the Korean Crop Experiment Station’s soybean (KLS) and the Korean Agricultural Development and Technology Center’s soybean (KADTC) collections, have been conserved at the Rural Development Administration (RDA) genebank in Korea. The accessions within collections were classified based on their traditional uses such as sauce soybean (SA), sprouted soybean (SP), soybean for cooking with rice (SCR), and OTHERS. A total of 2,758 accessions of Korean soybean landraces were used to profile and to evaluate genetic structure using six SSR loci. A total of 110 alleles were revealed by at the six SSR loci. The number of alleles per SSR locus ranged from 9 to 39 in Satt187 and Satt_074, respectively. The number of alleles ranged from 87 in the KADTC collection to 96 in the KLS collection, and from 63 in the SCR group to 95 in the SP group. Nei’s average genetic diversity ranged from 0.68 to 0.70 across three collections, and 0.64 to 0.69 across the usage groups. The average between-group differentiation (G _st) was 0.9 among collections, and 4.1 among the usage groups. The similar average diversity among three collections implies that the genetic background of the three collections was quite similar or that there were a large number of duplicate accessions in three collections. The selection from the four groups classified based upon usage may be a useful way to select accessions for developing a Korean soybean landrace core collection at the RDA genebank. DNA profile information of accessions will provide indications of redundancies or omissions and aid in managing the soybean collection held at the RDA genebank. The information on diversity analysis could help to enlarge the genetic diversity of materials in breeding programs and could be used to develop a core collection.     

Genetic diversity evaluation of a loquat (<Emphasis Type="Italic">Eriobotrya japonica</Emphasis> (Thunb) Lindl) germplasm collection by SSRs and <Emphasis Type="Italic">S</Emphasis>-allele fragments

Loquat (Eriobotrya japonica (Thunb.) Lindl.) is a minor Rosaceae fruit of growing interest as an alternative to the main fruit crops. In this context, the selection of new cultivars to satisfy the market demand will request the suitable characterization of the available germplasm. In this work, genetic relationships among 83 loquat accessions from different countries belonging to the European loquat germplasm collection, held at the Instituto Valenciano de Investigaciones Agrarias (IVIA) in Moncada (Spain) were evaluated using microsatellites and S-allele fragments. A total of nine single sequence repeats (SSRs) from Malus and Eriobotrya genera revealed 53 informative alleles and the S-RNases consensus primers detected 11 self-incompatibility putative alleles. The combined data allow to distinguish unambiguously 80 out of the 83 accessions studied. Unweighted pair-group method (UPGMA) cluster and principal coordinates analysis (PCoA), based on Dice’s genetic distance, generally grouped genotypes according to their geographic origins and pedigrees. Discrepancies and similarities of the results obtained with other variability analysis, based on pomological traits or molecular markers, on the same loquat collection are discussed.     

Estimation of phenotypic divergence in a collection of <Emphasis Type="Italic">Capsicum</Emphasis> species for yield-related traits

Phenotypic divergence among the 24 accessions belonging to a collection of six species of Capsicum from different geoclimatic regions available in field gene bank of CIMAP, Lucknow, India, was quantified by multivariate analysis for 12 quantitative and qualitative traits. Based on their values, all 24 accessions were grouped into six clusters such that the genetic stocks within cluster had smaller D ² values among themselves than those belonging to different clusters. The accessions of Capsicum annuum were distributed in different clusters in morphotyping representing different species, suggesting that taxonomic characteristics are not always related to agronomic traits. No parallelism/association was found between geographical and phenotypic diversity. Accessions 15 and 23 (clusters V and VI, respectively) had distinct identity. The three characteristics that played the greatest role in differentiation were fruit diameter, number of fruits per plant, and leaf diameter, which can be utilized as conventional/morphological markers for the improvement of chilli yield and obtaining good segregants in chilli breeding programs.     

Sources of resistance to diseases of sugar beet in related <Emphasis Type="Italic">Beta</Emphasis> germplasm: I. Foliar diseases

Resistance to four foliar diseases of sugar beet (Beta vulgaris ssp. vulgaris), virus yellows caused by Beet mild yellowing virus (BMYV) and Beet yellows virus (BYV), powdery mildew (Erysiphe betae) and Cercospora leaf spot (Cercospora beticola), was assessed in up to 600 accessions of closely related wild and cultivated Beta species. Most accessions were from the Section Beta, a taxon containing types most closely related to, and sexually compatible with, sugar beet and therefore most valuable for use in crop improvement. Between 1–12% of accessions were highly resistant (resistance scores of 2 on an international standardised resistance scale of 1–9) to these diseases. These levels, however, underestimate the potential number of resistant sources available from this section as some accessions with intermediate mean resistance scores contained a significant proportion of highly resistant plants within segregating populations. Variation in resistance to all diseases except BYV was observed within the Section Beta. Much higher levels of resistance were observed, and more frequently, in more distantly related sections of the genus Beta. Accessions of the Section Corollinae were highly resistant to both viruses (>62% of accessions tested), but less so to Cercospora (15%) and they were very susceptible to powdery mildew. Section Procumbentes accessions were highly resistant to BMYV and Cercospora (100%) but less so to powdery mildew (50%) and BYV (20%). However, sexual incompatibility between these sections and sugar beet make utilisation of these sources impractical using conventional breeding methods.     

Agro-morphological characterisation of common vetch and its close relatives

The Vicia sativa aggregate, which includes the common vetch, is a complex of six closely related tax a which combines cultivated, weedy and wild forms. In this study 454 accessions with an emphasis on Mediterranean and Central Asian accessions have been compared for 22 key agro-morphological and phonological characters. The agronomic potential of the different members of the aggregate is assessed and useful variation existing in the collection is determined. Geographic patterns of the agronomic variation are studied to determine sources of useful variation. In both sub sp. cordata and sub sp. sativa accessions were found which had higher yields than the checks, consisting of three promising accessions. Sub sp. macrocarpa needs a longer growing season than the other tax a to reach its full potential. The other three tax a in the aggregate all had quite low yields. Important variation in shattering of pod sand in tolerance to moderate frost and resistance to the Sitona weevil was found in most subspecies of the aggregate. Variation in phenological characters appeared to be related to the latitude from which the accession was collected. This revised version was published online in July 2006 with corrections to the Cover Date.