AlomySys: Modelling black-grass (Alopecurus myosuroides Huds.) germination and emergence,in interaction with seed characteristics,tillage and soil climate: II. Evaluation

Weed emergence models are increasingly necessary to evaluate and design cropping systems. The model AlomySys was developed for a frequent and harmful weed, i.e. Alopecurus myosuroides Huds. [Colbach, N., Dürr, C., Roger-Estrade, J., Caneill, J., 2005a. How to model the effects of farming practices on weed emergence. Weed Res. 45, 2–17; Colbach, N., Dürr, C., Roger-Estrade, J., Chauvel, B., Caneill, J., 2005b. AlomySys: modelling blackgrass (Alopecurus myosuroides Huds.) germination and emergence, in interaction with seed characteristics, tillage and soil climate. I. Construction. Eur. J. Agronomy] and is based on sub-models predicting (a) soil environment (climate, structure) resulting from the cropping system and external climate, (b) vertical soil seed distribution after tillage, and (c) seed survival, dormancy, germination and pre-emergent growth depending on soil environment, seed depth, characteristics and past history. In the present paper, the model was evaluated by comparing its simulated output to independent field observations, as a function of sowing/tillage date, seed depth, seed history and characteristics, soil climate and soil structure. The evaluation showed that the survival of the seed bank in top layers was systematically overestimated. In addition, some minor aspects were identified for future improvements, such as the pre-emergent seedling mortality in very compacted soil structures or germination rates of seeds that had not been previously stimulated by light. Despite these few shortcomings, the model simulates the timing and relative importance of the emergence flushes very well; in addition, the actual emerged seedling densities are usually predicted satisfactorily. Consequently, the model can be used to simulate the effects of cropping systems on black-grass emergence.     

AlomySys: Modelling black-grass (Alopecurus myosuroides Huds.) germination and emergence,in interaction with seed characteristics,tillage and soil climate: I. Construction

Models quantifying the effects of agricultural practices on weed emergence, in interaction with the soil, are necessary to evaluate and design cropping systems. In the present study, such a model was developed for black-grass (Alopecurus myosuroides Huds.), a harmful weed frequently found in rotations consisting mostly of winter crops. The model AlomySys was based on sub-models predicting (a) soil environment (climate, structure) resulting from the cropping system and weather, (b) vertical soil seed distribution after tillage, depending on the tool, the characteristics of the tillage implement and the soil structure; and (c) seed mortality, dormancy, germination and pre-emergent growth depending on soil environment, seed depth, characteristics and past history. Seed movements during tillage depend on the tool used, its characteristics, soil structure and on the initial position of the seed. Seed mortality increases with seed age; seed dormancy depends on seed age, seed depth, the conditions in which the seeds were produced and the past moisture and dryness conditions undergone by the seeds; germination is triggered by rain or tillage and driven by hydro-thermal time; pre-emergent shoot elongation depends on seed weight, on the conditions in which the seeds were produced and increases with thermal time; pre-emergent seedling mortality increases with soil dryness, clod size and seed depth. The sub-models were based either on existing models, or developed with literature data or additional experiments. Simulations were carried out to show how weed emergence can be reduced by adapting tillage mode and date to previous crop history.     

Competitive Interactions between First-year Seedlings of Timothy (Phleum pratense L.) and Meadow Fescue (Festuca pratensis Huds.)

Shoot- and full-competition between first-year seedlings of meadow fescue (Festuca pratensis Huds.) and timothy (Phleum pratense L.) was studied m two separate experiments in a greenhouse. Timothy had a higher competitive ability than meadow fescue and produced more tillers, had a higher shoot weight and a larger leaf area in all strata of the canopy.
Competition for light was important up to the first harvest. The upright growth form of timothy plants during the reproductive phase enabled them to shade the unvernalized and prostrately-growing meadow fescue. Root competition may have been important afterwards. After the first harvest, tiller formation in timothy plants was high, and significantly enhanced when grown with meadow fescue. Meadow fescue produced few new tillers, and its tiller formation was depressed when competing with timothy.     

The Change of Heat Emission and Phenolic Compound Level in Hordeum vulgare (L.) and Festuca pratensis (Huds.) Calli Treated with Bipolaris sorokiniana (Sacc.) Shoem. Phytotoxins

The presented work was conducted on calli of spring barley and meadow fescue that differed in degree of sensitivity to leaf spot pathogen Bipolaris sorokiniana . Callus reaction to fungus phytotoxins was examined on the basis of the amount of total phenolics and heat emission. The study was conducted dynamically – the measurements were performed after 1, 3, 6, 10, 24, 48, 72, 168 and 240 h after the moment when the calli were elicited with fungus metabolites. The greatest metabolic activity of fescue calli was observed between the 6th and the 24th h after treatment with phytotoxins and amounted to 170 % of control values. On the 10th day of culture this activity dramatically decreased in comparison with control (17 %). In the case of barley calli, increased heat emission was registered during the first 10 h of pathogenesis (130–150 % of control values). Calli of both studied plant species also differed in the dynamics of phenolic content changes. In meadow fescue tissue a significant decrease in phenolic level in comparison with control (40 %) was observed after the 7th day of experiment. In barley calli the amount of total phenolics decreased within the first 3 h (60–70% of control). The results obtained show that spring barley and meadow fescue differ in the rate of reaction to B. sorokiniana phytotoxins with regard to changes in metabolic activity and phenolic content. It also suggests a different degree of the plants sensitivity to the studied pathogen on tissue level.     

Competition Between Meadow Fescue (Festuca pratensis Huds.) and Timothy (Phleum pratense L.) at Three Levels of Nitrogen Fertilization, During Three Growing Seasons

Competition between timothy ( Phleum pratense L.) and meadow fescue ( Festucapratensis Huds.) under three levels of nitrogen was studied during three growing seasons under northern climatic conditions, 69° N latitude. Timothy initially had higher competitive abilities, particularly when nitrogen was added, but due to a higher regrowth capacity, meadow fescue was able to compete with timothy increasingly over time. The species differed in their growth patterns. Timothy had a higher proportion of reproductive tillers and a larger leaf area in the upper parts of the canopy at the first harvest, especially at high nitrogen-fertilization. Consequently, timothy shaded meadow fescue during the reproductive stage of growth. After defoliation, regrowth of timothy halted for one to two weeks. Meadow fescue, by contrast, had higher tiller numbers than timothy, a higher number of intact growing points, and resumed shoot-growth rapidly after defoliation. Due to these traits, the competitive abilities of meadow fescue increased each year relative to timothy.     

Effect of Management Intensities and Sward Structures on Dry-matter Production of Meadow Fescue (Festuca pratensis Huds.) in Permanent Grassland

A 3-year experiment was conducted on an extensively managed hay meadow to assess the effect of management intensity and sward density on growth of meadow fescue. Two management treatments, intensive (6 cuts, 240 kg N ha−1 year−1) and extensive (3 cuts, 75 kg N ha−1 year−1), with and without gaps around the meadow fescue plants, were applied.
The highest yields were obtained under frequent defoliation. The yield of meadow fescue when grown in gaps increased four- to fivefold on an area basis in the first growing season, and reached a factor of 17 the following year. However, the difference between the treatments with and without gaps decreased strongly during the third growing season.
The contribution of meadow fescue to the total yield remained high and constant in swards with gaps combined with extensive management for the 3 years. In contrast, in swards with gaps combined with intensive management, the yield contribution of meadow fescue decreased, and in swards without gaps it remained very low under both management regimes.
The results show that meadow fescue was a weak competitor. Its response to management intensity was strongly affected by light intensity and soil water content. Low light intensity and dry top soils enhanced the suppression of meadow fescue.     

Hybridization of radish (Raphanus sativus L.) and oilseed rape (Brassica napus L.) through a flower-culture method

Summary Hybridization between radish and oilseed rape has been cumbersome, requiring elaborate embryo rescue techniques. With a modified flower culture method, we have achieved successful hybridization between radish and (transgenic) oilseed rape without the laborious and technically demandingin vitro ovule or embryo rescue techniques.The hybrid nature of the intergeneric hybrids was demonstrated using morphological traits, and DNA analyses. The described method will facilitate the generation ofRaphanobrassica hybrids useful for biosafety studies of the potential for transgenes to spread in weedyCruciferae as well as for breeding programs aimed at introducing useful radish genes, e.g. nematode resistance genes, into oilseed rape.     

Doubled haploid production of sunflower (Helianthus annuus L.) through irradiated pollen-induced parthenogenesis

Induced parthenogenesis as a possible method of haploidization in sunflower (H. annuus L.) was tested in previous investigations (Todorova et al., 1994) and conditions for reproducible regeneration of gynogenic doubled haploids were established by the present work. Forty eight treatments were studied, involving four pollen donors and four recipient hybrids. Pollen was irradiated with doses of 300 Gy, 600 Gy and 900 Gy. In total, 2279 embryos were cultivated in vitro of which 1107 plants were obtained and 582 of them produced seeds after selfing. The ploidy level of the regenerants was evaluated at the two – three leaf stage and 296 of the plantlets obtained were haploids. Some of them underwent spontaneous diploidization, the others were treated with colchicine solution for chromosome doubling. The diploid plantlets were checked for their gynogenic origin by genetical and biochemical methods. The effectiveness of the method expressed as the number of agronomically useful DH lines to the number obtained that were fertile and resistant to downy mildew, branched and unbranched plants was 8,6% on average. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of low linolenic acid rapeseed (Brassica napus L.) through protoplast fusion

Brassica napus somatic hybrids with low linolenic acid (18:3) content in their seed oil have been produced using fusion partners screened for low 18:3. One somatic hybrid contained only 3.5% 18:3, a level significantly below the mid-parental mean. The low level of 18:3 proved stable in the R₁ generation. Oil content of the lowest 18:3 selection increased from the mid-parental mean (29.3%) in the R₀ generation to 36% in a R₁ field bulk. The R₁ field population also showed some resistance to shattering. This revised version was published online in July 2006 with corrections to the Cover Date.     

Alternative strategies for nitrogen fertilization of overwinter processing spinach (Spinacia oleracea L.) in Southern Italy

To identify the best practice for nitrogen (N) fertilization of overwinter processing spinach, two field experiments were carried out in the Foggia plain (Southern Italy), one of the most vocated area for leafy vegetables production. The field trials were aimed to define and suggest the proper fertilizer dose, typology and the right time of application. Experiment 1 evaluated four N fertilizer doses (0, 150, 225, 300 kg ha⁻¹) in a two-year field trial. Experiment 2 was aimed to assess the effect of the split distribution of prilled urea fertilizer in comparison with the application of nitrification inhibitor (DMPP) containing urea fertilizer, broadcasted at sowing.Spinach yield, yield quality (nitrate – NO₃⁻ – and carotenoids content), N-use efficiency and risk of soil nitrate (NO₃⁻-N) leaching were evaluated. The processing spinach yielded 37.8 and 3.6 t ha⁻¹ of fresh and dry yield, respectively (average of the two experiments). Fresh and dry yield among the fertilizing treatments were similar. Also the β-carotene and the lutein content of spinach leaves (19.5 and 38.1 mg kg⁻¹, respectively) were not affected by the N fertilizer dose. Conversely, the N dose strongly influenced the NO₃⁻ content of the leafy vegetable tissues (1286 mg kg⁻¹ on average, 58% lower than the limits imposed by the EC regulation). As expected, the different rainfall pattern influenced both the leaf NO₃⁻ content and the risk of soil NO₃⁻-N leaching. The results achieved demonstrated that, in order to get a favorable trade-off, among yield, yield quality, N-use efficiency and environmental impact, the processing spinach growers of the Foggia plain area should be encouraged to apply 225 kg N ha⁻¹ as maximum fertilization rate. Also, the split urea fertilizer application appeared as the more effective strategy for N fertilization of overwinter spinach in comparison with the use of the nitrification inhibitor containing urea fertilizer, being the last strategy not able to adequately match the N crop demand.     

Population dynamics of volunteer oilseed rape (Brassica napus L.) affected by tillage

Volunteer plants of oilseed rape (Brassica napus L.) from persistent seeds in soil can affect subsequent crops. Apart from the agricultural disadvantages, the environment and the marketing of the seeds may also be affected, particularly if plants with special ingredients or genetically modified (gm) plants are grown. In order to investigate the influence of soil cultivation and genotype on seed persistence and gene flow via volunteers, a field experiment was set up testing four tillage treatments and two cultivars in a split-plot design. The cultivars tested were near-isogenic to two gm cultivars. To simulate harvesting losses, 10 000 seeds m⁻² were broadcast on a soil in July. The subsequent tillage treatments were combinations of immediate or delayed stubble tillage by a rotary tiller, primary tillage with plough or cultivator, or zero tillage. Over the following year, the fate of the seeds was determined. Immediate stubble tillage with following cultivator or plough resulted in 586 resp. 246 seeds m⁻² in the soil seed bank. After delayed stubble tillage with following plough, 76 seeds m⁻² were found, and no soil seed bank was built up in the zero tillage treatment. Nevertheless, in the zero tillage treatment, several robust volunteer plants survived the herbicide application before the direct drilling in autumn until following spring. In the zero tillage treatment and in the cultivator treatment, 0.19 volunteers m⁻² resp. 0.06 volunteers m⁻² flowered simultaneously to ordinarily sown oilseed rape in the following crop of winter wheat and produced 73 resp. 18 seeds m⁻². Delayed stubble tillage reduced the risk of gene escape via the soil seed bank, while zero tillage resulted in the highest risk of gene escape by pollen and by production of a new generation of seeds. In terms of a labelling threshold for gm food this number of seeds would be below the threshold of 0.9% of transgenic parts in conventially bred food or feed.     

Genotypes of Perennial Ryegrass (Lolium perenne L.) with High Anther-Culture Response through Hybridization

Anther-culture response in Lolium perenne was studied in the hybrid populations from three responsive diploid parent clones to obtain genotypes with superior anther-culture response through hybridization. Genetic variation for anther-culture response was significant both within and between the four hybrid families and their parents. A reciprocal effect was indicated for embryo formation and regeneration percentages for one of the cross combinations. Among 55 hybrid clones tested in two environments, 6 clones were identified with an anther-culture response level superior to their parents. While the parents produced one green plant or less per 100 anthers, these superior clones produced from 11 to 59 green plants/100 anthers, mainly as the result of improved embryo formation and improved percentages of regenerated plants being green. A significant correlation (r = 0.397^**) was observed between embryo formation and percentage of green plants. The results are discussed with regard to the possible transfer of anther-culture response to non-responsive breeding material through hybridization.     

Breeding of widely compatible restorer lines in rice (Oryza sativa L.) through anther culture

Following anther culture of various F₁ hybrids of indica restorer (R) lines/wide compatible varieties (WCVs) and japonica R lines/WCVs, the homozygous diploid plants (2n) generated were test-crossed with indica WA type cytoplasmic-genetic male sterile (CMS) line Zhanshan 97A (WA), indica testers Nanjing 11 and Nante, japonica BT CMS line Hanfeng A (BT), and japonica testers Balilla and Akihikari to identify widely compatible restorer lines. The results of this study showed that among the diploid pollen plants generated from F₁ hybrids of indica R lines/WCVs, 36.7% and 64.7% possessed normal fertility restoration ability (rate of seed-setting > 80%) to Hanfeng A and Zhanshan 97A, respectively. 71.3% and 32.3% had normal fertility restoration ability to Hanfeng A and Zhanshan 97A, respectively, in diploid pollen plants derived from the japonica R lines/WCVs F₁'s anther culture. Several widely compatible R lines were selected from anther culture of F₁ hybrids of indica R lines/WCVs and japonica R lines/WCVs. These widely compatible R lines derived from diploid pollen plants showed good wide compatibility and restoration ability both to WA and BT type CMS lines. Strong standard heterosis of major agronomic traits and yield traits was observed in F₁ test-crosses of widely compatible R lines with Hanfeng A and Zhanshan 97A. The wide compatibility in widely compatible R lines H17, H158 and H281 was studied by a set of three-way crosses. Segregation of the fertile plants with seed-setting rate > 70% and semi-fertile plants with seed-setting rate > 69.9% agreed with a ratio of 1:1, indicating that wide compatibility in these widely compatible R lines is governed by a pair of major genes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reinventing heterosis phenomenon through deployment of alien introgression lines in rice (Oryza sativa L.)

Introgression Lines (ILs) carrying alien genomic segments in the homozygous state may or may not be able to contribute positively to the phenotype on account of replacement of cultivated genome segment, however, the genetic elite in heterozygous condition can be attributed to the presence of both recipient and donor genome complements. Therefore, overdominance or pseudo‐overdominance effect at the heterozygous loci is anticipated. Set of 318 ILs, carrying several genomic segments from “A” genome donor wild species, were used for developing test hybrids with CMS line PMS17A. Of these, three hybrids observed significant yield advantage (>25%) over recurrent parents and checks. Parental ILs of these hybrids viz., IL326, IL901 and IL951 carried 5.62%, 2.52% introgression from Oryza rufipogon and 6.71% from Oryza nivara, respectively. These ILs were also crossed with their recurrent parent to develop introgression line hybrids (ILHs) to observe the contribution of the alien segment(s), in the homozygous and heterozygous state. The traits studied have higher mean value when genomic segments from wild species were in the heterozygous state as compared to the homozygous state.     

The dynamics of lucerne (Medicago sativa L.) yield components in response to defoliation frequency

The productive life of lucerne (Medicago sativa L.) stands depends on the rate of mortality of individual plants. However, self-thinning of plant populations may be compensated for by increases in other yield components, namely shoots/plant and individual shoot mass. Frequent defoliation reduces lucerne yield but it is unclear whether this is caused by an acceleration of plant mortality or changes in these other yield components. To investigate this, crops with contrasting shoot yields were created using constant 28 or 42-day regrowth cycles applied to a ‘Kaituna’ lucerne crop in Canterbury, New Zealand during the 2002/2003 and 2003/2004 growth seasons. Two further treatments switched from 28 to 42 or 42 to 28 days grazing frequency in mid-summer (4th February) of each year. The annual yield of shoot dry matter (DM) ranged from 12 to 23 t/ha for the treatments defoliated consistently each 28 or 42 days, respectively. Plant population was unaffected by treatments and declined exponentially from 130 plants/m² in June 2002 to 60 plants/m² in September 2004. The dynamics of plant and shoot population were associated with the light environment at the base of the canopy. The slope of the size/density compensation (SDC) of plants was −1.67 for the treatment defoliated each 42 days, near the expected self-thinning slope of −1.5 for stands at constant leaf area index (LAI). Self-thinning of shoots resumed after each defoliation when the LAI reached 2.1 and the transmission of photosynthetically active radiation (PAR_t) was 0.20. At this point the proportion of aerial DM in the tallest (dominant) shoots increased non-linearly from 30 to >80%, due to the mortality of intermediary and suppressed shoots. The average maximum shoot population in each rotation was 780 shoots/m² and unaffected by the decline in plant population due to a compensatory increase from 6 to 13 shoots/plant as the stand thinned. A lower asymptote of 43 plants/m² was estimated as the minimum plant population at which yield component compensation would maintain the productive potential of these ‘Kaituna’ stands. Differences in shoot yield were explained (R² = 0.97) by changes in the individual shoot mass (ISM) that were consistently lowered by frequent defoliation treatments. Frequent defoliations reduced crop productivity by limiting the assimilation of biomass into each individual shoot with negligible impact on shoot appearance rate, the number of shoots per plant at an LAI of 2.1 or the rate of plant population decay. Inter-specific competition for light was proposed as the main factor controlling self-thinning of plants and shoots regardless of their individual C:N status.     

Current status and future strategies of in vitro culture techniques for genetic improvement of mungbean (Vigna radiata (L.) Wilczek)

Summary Mungbean is an important source of vegetable protein for the growing population in many developing countries of South East Asia. Its production is limited due to its susceptibility to diseases and insect pests besides many other undesirable agronomic traits. Strategies for increasing and stabilising its production have been to develop varieties resistant to diseases, pests and with other desirable agronomic traits. Genetic improvement of this crop by classical breeding has met with limited success due to the lack of sufficient and satisfactory level of genetic variability within germplasm. Recent advances in biotechnology have offered the opportunity to develop new germplasms. The development of such technologies largely depends on efficient regeneration of sexually mature plants from organs, tissues and protoplasts. An overview of plant regeneration by direct or indirect organogenesis and embryogenesis is presented. The use of in vitro and molecular techniques such as somaclonal variation, screening for various desirable traits, interspecific crossing and genetic transformation to supplement conventional breeding, for genetic improvement of this crop is described. The advantages and limitations of these techniques along with directions for future research are discussed.     

Obtention of haploid embryos and plants through irradiated pollen technique in squash (Cucurbita pepo L.)

The influence of gamma ray doses (25, 50, 75, 100, 200, 300 and 400 Gy) and genotypes (Eskenderany F₁, Acceste F₁, Sakiz, Urfa Yerli) on the induction of haploid embryos obtained by irradiated pollen technique was studied in squash (Cucurbita pepo L.). Different shapes and stages of embryos were derived from seeds extracted from fruits harvested 4–5 weeks after pollination. As a result of the present study, haploid embryos and haploid plants were obtained, with haploid production strongly influenced by gamma ray doses, embryo stages and genotypes. Gamma ray doses of 25 and 50 Gy gave the highest parthenogenetical response. All of the point shape, globular shape, arrow tips and stick-shaped embryos developed into haploid plants. However, only 53.8% of torpedo and 23.1% of heart-shaped embryos gave haploid plants. In contrast, cotyledon-shaped and amorphous-shaped embryos produced only diploid plantlets. The number of embryos per 100 seeds was the highest in ‘Eskenderany F₁’ and ‘Sakiz’ genotypes. After in vitro culture, a total of 93 haploid plantlets were obtained. This revised version was published online in August 2006 with corrections to the Cover Date.     

Enhanced anther culture efficiency of indica rice (Oryza sativa L.) through modification of the culture media

The production of microspore-derived green plants from anther culture of indica rice is generally very low compared with japonica cultivars. A modified anther culture medium, consisting of a higher KNO₃ content (31 mm ) and casein hydrolysate (CH, 500 mg/1) but without ammonium salts, was tested in comparison with a medium consisting of the widely-used N6 medium nitrogen background, using four indica × indica F₁ hybrids as test materials. Green plant regeneration frequency was at least three-fold higher in the microspore-calli derived from the former medium than in those derived from the modified N6 medium. More than 700 microspore-derived plants were raised in the field. Another study was carried out using indica × japonica and indica × javanica F₁ hybrids. The results indicated that a medium with higher (3.5 mm ) ammonium sulphate may induce a higher frequency of anthers with microspore-calli but not necessarily lead to a larger number of green-plant regenerating calli. Subsequently, using the indica cv. ‘IR-43’ as the test material, use of a lower level (1.75 mm ) of (NH₄)₂SO₄, in addition to KNO₃ (31 mm ), was found to be better than CH (500 mg/l) for anther-response as well as green plant regenerability of the derived microspore-calli. Nitrate-nitrogen or ammonium-nitrogen alone elicited poor response. Twenty-five media involving combinations of KNO₃ (20–34 mm ) and (NH₄)₂SO₄ (1–3 mm ) were tested for their effects on anther response. Combinations involving KNO₃ (31–34 mM) and (NH₄)₂SO₄ (2.0–2.5 mm ) were found superior not only for achieving greater anther response but also, for subsequent green-plant regeneration. This contrasts with the 28 mm of KNO₃ and 3.5 mm of (NH₄)₂SO₄ in the widely-used N6 medium developed for japonica rice. Other than potassium nitrate and ammonium sulphate, and potassium phosphate to some extent, the levels of other inorganic salts tested did not make any significant difference to the process of anther response. Based on these results, modified media with three levels of ammonium sulphate were tested for anther culture efficiency of indica × japonica and indica × javanica derivatives (F₃s). Microspore-calli derived from a medium of a lower (1.75 mm ) level of (NH₄)₂SO₄ showed a higher regeneration potential overall than those derived from a higher (3.5 mm ) level. A revised medium has been suggested, on the basis of these results, for the realization of improved anther culture efficiency and, consequently, improved feasibility of using doubled haploids in genetic and breeding research with indica rice.     

Biochemical characterization of white onion landraces (Allium cepa L.) through HPLC analysis of endosperm seed proteins

Water-, salt-, alcohol- and alkali-soluble seed storage proteins, extracted from 21 cipolla bianca di Pompei landraces (Allium cepa L.), were analyzed by anionic exchange-high performance liquid chromatography (AE-HPLC). Chromatographic elution profiles (time range 0–40 min) at 280 nm of water-soluble seed proteins evidenced the presence of 21 peaks, which allowed all the landraces studied to be distinguished from each other. The differences detected were both qualitative (presence/absence of one or more peaks) and quantitative; the water-soluble proteins were useful in differentiating landraces and cultivars while the other seed protein fractions only showed a weak polymorphism. The cluster analysis, based on HPLC data, showed that the landraces clustered with a genetic similarity degree ranging between 69% and 94%. The possibility of discriminating among closely related onion landraces during the course of breeding programmes could allow the identification of biochemical markers linked to useful agronomical traits. As observed by chromatographic analysis, the globulin composition of onion water-soluble seed protein appears to be independent of environmental growth conditions. The biochemical characterization of the available typical onion germplasm may contribute to obtain a community recognition and denomination, such as Denomination of Protected Origin (D.O.P.), Indication of Protected Origin (I.G.P.) or Specificity Attestation (A.S.). The biochemical method here developed resulted of high resolution, cost-effective and time-saving for characterization and genetic purity assessment of the landraces studied.