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Proceeding of the 4 rd International Symposium“NEW RESEARCH IN BIOTECHNOLOGY” USAMV Bucharest, Romania, 2011In conventional production, seed pathogens are controlled by fungicides but in bio-farmingno effective methods of control are defined. This requires the study of seed pathology indifferent ways of cultivating the crop in order to establish methods of biological controlagainst phytopathogenic seed parasites.382. MATERIAL AND METHODSThis experiment has been carried out in the Plant Protection Laboratory ofAgricultural Institute in Shumen.Test subjects were wheat and barley seeds harvested in 2006, 2007, 2008 and 2009 fromthe institute’s experimental fields, where two six-pole crop rotation fields were set up withcereal and grain legumes, grown by two different technologies – eco-friendly andconventional.The eco-field was fertilized only with manure and no pesticides during vegetation wereapplied. If needed, the application of harmless for the useful micro flora and entomofaunamedicines is allowed, included in the so called “Green list”.With cultures grown by conventional technology, the field is fertilized with mineralfertilizers and pesticide treatment is used against sicknesses and vermins.Those two fields were created on an identical soil type with similar parameters fornutrient reserves. Soil in testing fields is carbonate black soil with high humus content inthe plowing layer (3,7 – 3,74%) and weak alkali reaction (pH 7,7 – 8,1).Materials for phytopathological analysis of crops grown in eco-friendly conditionsand by conventional technology were included in the tests.Seed analysis was carried out by the method of placement in Chapek environment,100 seeds for phytopathological evaluation being set from all four options (wheat andbarley from the eco-field and wheat and barley from the conventional field).After a 7 days cultivation period in a thermostat at t 24-26 0 C pure cultures have beenisolated from the test plates from the conventional methods and the pathogens in sampleshave been defined.The count of infected seeds for different species of fungi has been reported in %and the statistic processing has been carried out by the Mudra (1958) method.3. RESULTS AND DISCUSSIONSAfter the mycological analysis it was determined that microscopic fungi of thefollowing 8 species are present in tested samples –Fusarium, Alternaria, Mucor,Penicillium, Botrytis, Cladosporium, Rhizopus and Helminthosporium.Fig. 1 shows the average percentage of contamination of seeds with the according fungi.It stands out that in the composition of seed micro-flora, the percentage of Fusariumfungi (53%) and Alternaria fungi (32%) is significantly higher than that of other fungi(Mucor, Penicillium, Botrytis, Cladosporium,Rhizopus and Helminthosporium ), whosepercent of contamination varies in a narrow range (1%-6%). Similar results are reported byother authors studying the seed pathology in wheat and barley (Valcheva, A., 2006;Karadjova, I., 1979; Ivanov, M., 1980), who find highest percentage fungal infection withspeciesFusarium and Alternaria.
Proceeding of the 4 rd International Symposium“NEW RESEARCH IN BIOTECHNOLOGY” USAMV Bucharest, Romania, 2011Fig. 2 shows the ratio of different kinds of Fusarium species in samples. The highesttotal percentage is that of seeds contaminated with F.graminearum (50%), followed byF.moniliforme (36%) and F.oxysporum (14%) which shows that among fungi of Fusariumspecies on barley and wheat grown in North-East Bulgaria, most common areF.graminearum.These results differ from Valcheva’s (studied fusariosis on those sameplants in North-West Bulgaria), where for the period 1994-2004 she has found a greaterpercentage of contamination with F.moniliforme.Table 1 shows the mycological status and the total percentage of infected wheat and barleyseeds from the eco- and the conventional fields during the period 2006-2009.Data shows that fungiAlternaria and Fusarium are noted in different quantities in allsamples from both crops in separate years. Most infected with Fusarium fungi are materialsharvested from the conventional field (average wheat – 34%, and barley – 16,5%). Seedsinfected by Alternaria can be found in larger quantities in the eco-field (average wheat –18,5% and barley – 16,5%).The presence of the so called “storage fungi” in the complex of seed parasites (Mucor andPenicillium) is weak (average 0,5 – 3%) and no significant differences are found in separatecrops, as well as the same crops, cultivated in different conditions.Microscopic fungi from the species Botrytis are detected only in wheat samples from theeco-field, and species Cladosporium and Rhizopus are isolated only in barley samples,grown by conventional technology.Seed infection with pathogens from species Helminthosporium is registered in very smallquantities (1,5 – 1,75%) in analyzed materials from the conventional field.Table 2 shows data from statistical processing and compares results from thephytopathological analysis of both crops – wheat and barley grown by the eco- andconventional technologies regarding the total contamination of their seeds with fungi fromthe species Alternaria and Fusarium during the four-year period of the study.Analysis shows that there is a proven difference in resistance against seed pathogens fromthe species Fusarium of wheat and barley grown in eco-conditions.With conventionally grown barley, fungi from the species Alternaria have a proven strongerparticipation in samples, and in eco-wheat this difference is very well insured.4. CONCLUSIONS- The percentage of fungi of the species Fusarium (53%) and Alternaria (32%) inseed micro-flora is significantly higher than that of other fungi (Mucor, Penicillium,Botrytis, Cladosporium, Rhizopus and Helminthosporium ), whose percentage ofcontamination varies in a narrow range (1%-6%).- From fungi of the species Fusarium the highest percentage of infected seeds is that withF.graminearum (50%), followed by F.moniliforme (36%) and F.oxysporum (14%).- Fungi of the species Fusarium and Alternaria are found in all tested samples.- Seeds from the conventional field are more contaminated with fungi Fusarium, while theeco-field is more contaminated with fungi Alternaria.39
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