Non-disinfected Seeds Research Articles

ПОСІВНІ ЯКОСТІ НАСІННЯ ЕХІНАЦЕЇ ПУРПУРОВОЇ (ECHINACEA PURPUREA (L.) MOENCH.)

The energy of germination and laboratory germination of Echinacea purpurea seeds have been studied, as it is the sowing qualities of seeds that are the basis for successful reproduction of the species in culture. Peculiarities of germination of culture seeds depending on harvest terms are studied. It is noted that the seeds of 2017-2018 are not conditioned and are not recommended for cultivation in medicinal crops in order to obtain quality medicinal raw materials according to generally accepted standards, while the seeds of 2020 harvest have a fairly high quality and belong to the basic category. The article also presents data on the effect of disinfection with ethyl alcohol on the sowing qualities of Echinacea purpurea seeds, the tendency to increase germination energy and germination in the variant with treated seeds. Seeds, endowed with a high rate of laboratory germination, belongs to the category of original and is recommended for further propagation. Such seeds may have good field germination, although this figure will be slightly lower in any case, because the laboratory for growing seeds creates optimal conditions, which is not always possible in the field. This is usually associated with the influence of biotic and abiotic factors: temperature, humidity, light, conditions and timing of sowing, soil fertility, its infestation by pests and pathogens, and so on. In the course of studies of germination energy and laboratory germination, attention was paid to the degree of damage to the seeds of Echinacea purpurea by mold fungi. On average, when determining the energy of germination, the degree of damage by molds was weak, but when determining laboratory germination, a large degree of damage to achenes by molds was additionally manifested. When comparing the degree of fungal infestation of treated and non-disinfected seeds, we noted a low degree of infestation (for disinfected achenes) and a medium degree of infestation (for non-disinfected seeds). When determining the germination energy of disinfected echinacea seeds, the signs of purple lesions were generally invisible.

Effects of Mechanical Weed Control in Barley-Pea Mixture on Colonization of Pea Seeds by Fungi, Part 2

Our study was a mycological evaluation of pea seeds harvested from a barley-pea mixture in which different methods of weed control had been used. The field experiment was carried out during 2010-12 and was conducted using randomized block design in four replicates. Weed control was mechanical and chemical. Fungal colonization tests were carried out on disinfected and non-disinfected seeds. The research showed statistically significant differences in the total number of fungi isolated from disinfected and non-disinfected seeds. The fungus most frequently isolated was Alternaria alternata. Penicillium chrysogenum, Sclerotinia sclerotiorum, and Trichoderma harzianum were isolated only from the non-disinfected seeds. Presented results show that suitably chosen mechanical weed control may be an alternative to chemical weed control in the mixtures of cereals and legumes, and may be particularly important for organic and integrated farming. The best variant of mechanical weed control in the cereal-legume mixture in terms of infection pea seeds by fungi is two passes of spring-tine harrow at the beginning of the tillering stage of barley and two passes at the full tillering stage of barley.

Pathogenic Fungi Transmitted Through Cucumber Seeds and Safely Elimination by Application of Peppermint Extract and Oil

Diseases induced by Fusarium, like damping-off and wilt on cucumber, are serious problems around the world. Samples of cucumber seeds were collected from commercial markets in Egypt and tested for seed-borne fungi. In order to detect the maximum number of internal and external seed-borne fungi, agar plate examination of disinfected and non-disinfected seeds were used. Two species of Fusarium were the most frequent and predominant fungi. Facultative parasites of the genera Alternaria, Rhizoctonia, Helminthosporium and Penicillium were also found. A total 33 isolates of Fusarium spp. were obtained using Komada’s selective medium. Fusarium oxysporum and F. solani were highly frequent. Pathogenicity test indicated that, F. oxysporum isolate (Fem8) was the main causal organism of pre- and post-emergence damping off. Furthermore, it occurred in all seed parts tested. Some infected seeds germinate, but they were either rapidly overgrown by F. oxysporum or they developed into a diseased seedling. The water extract of garlic, peppermint and rheum completely inhibited the conidiospore germination and mycelial growth of F. oxysporum at tested conc. 3, 2 and 3%, respectively. Soaked seeds in 2% peppermint extract and evaporated seeds by vapor of peppermint oil caused a highly reduction in the infection and reduced transmission of the referred fungi from seeds to the growing seedlings. The vigor of cucumber seedlings raised from the treated seeds was better than that developed from untreated ones.

Fungi isolated from Stewartia pseudocamellia Max. seeds and their pathogenesis

The aim of studies was to determine typical composition of fungi occurring on seeds of <i>Stewartia pseudocamellia</i>.The studies conducted on 100 disinfected and 100 nondisinfected seeds of these plants.Isolates of <i>Alternaria alternata</i>, <i>Fusarium oxysporum</i>, <i>Cylindrocarpon radicicola</i> and <i>Rhizoctonia solani</i> were characterized by pathogenicity towards the investigated <i>Stewartia pseudocamellia</i>. In the laboratory experiment, 204 isolations of microorganisms were obtained that belonged to 20 species and form of fungi and bacteria. Among fungi there were both of parasite (<i>Alternaria alternata</i>, <i>Botrytis cinerea</i>, <i>Fusarium</i> spp., <i>Rhizoctonia solani</i>) and typical saprophytic (<i>Cladosporium</i> spp., <i>Penicillium</i> spp., <i>Aspergillus</i> spp., <i>Epicoccum</i> spp., <i>Mucor</i> spp.). The dominant fungus on seeds was <i>Alternaria alternata</i>. Among the investigated isolates only one isolate (R4) <i>Rhizoctonia solani</i>, was strongly pathogenic, isolates (A1) <i>Alternaria alternata</i> were weakly pathogenic to seedlings of <i>Stewartia pseudocamellia</i>.

The Effect of Seed-borne Mycoflora from Sorghum and Foxtail Millet Seeds on Germination and Disease Transmission

The seed-borne mycoflora of sorghum and foxtail millet collected from different growing areas in South Korea were isolated and taxonomically identified using dry inspection, standard blotter and the agar plate method. We investigated the in vitro and in vivo germination rates of disinfected and non-disinfected seeds of sorghum and foxtail millet using sterilized and unsterilized soil. The percent recovery of seed-borne mycoflora from the seed components of sorghum and foxtail millet seeds was determined and an infection experiment using the dominant species was evaluated for seedling emergence and mortality. A higher number of seed-borne fungi was observed in sorghum compared to that of foxtail millet. Eighteen fungal genera with 34 fungal species were identified from the seeds of sorghum and 13 genera with 22 species were identified from the seeds of foxtail millet. Five dominant species such as Alternaria alternata, Aspergillus flavus, Curvularia lunata, Fusarium moniliforme and Phoma sp. were recorded as seed-borne mycoflora in sorghum and 4 dominant species (Alternaria alternata, Aspergillus flavus, Curvularia lunata, Fusarium moniliforme) were observed in foxtail millet. The in vitro and in vivo germination rates were higher using disinfected seeds and sterilized soil. More seed-borne fungi were recovered from the pericarp compared to the endosperm and seed embryo. The percent recovery of seed-borne fungi ranged from 2.22% to 60.0%, and Alternaria alternata, Curvularia lunata and 4 species of Fusarium were isolated from the endosperm and embryo of sorghum and foxtail millet. Inoculation of the dominant seed-borne fungi showed considerable mortality of seedlings. All the transmitted seed-borne fungi might well be a primary source of infection of sorghum and foxtail millet crops.

Mycoflora in Exhumed Seeds ofOpuntia tomentosaand Its Possible Role in Seed Germination

The funicular cover of theOpuntia tomentosaseed limits imbibition; germination occurs only when the funicle is weakened or the funicular valve is removed. We investigated the role of fungi in funicular weakening and seed germination. Seeds that had been either buried in one of two sites or stored in the laboratory were germinated with and without a valve. Disinfected or nondisinfected seeds and their naked embryos were cultivated on agar or PDA. None of the 11 identified fungal genera grew on the disinfected control seeds or the embryos. The mycoflora present on disinfected and nondisinfected exhumed seeds suggest that the fungal colonization occurred in the soil and differed between the burial sites. Exhumed seeds with and without a valve germinated in high percentages, whereas only the control seeds without a valve germinated. Scanning electron micrographs showed that the hyphae penetrated, cracked, and eroded the funicular envelope of exhumed seeds.

Vitality and Healthiness of Barley (Hordeum Vulgare L.) Seeds Treated with Plant Extracts

The aim of presented experiments was to determine the usefulness of plant extracts for dressing of cereal seeds. Water ex- tracts (macerations, infusions) prepared from different morphological parts of 39 plant species were used as dressing preparations. Non-disinfected seeds of two cultivars of barley (Hordeum vulgare L.): Rudzik (brewing barley) and Stratus (common barley) were used for the purpose of dressing. The experiment was conducted as a filter paper test (PN-94 R-65950) while determining the germina- tion viability (1st date) and the germination capacity (2nd date) as well as the healthiness of the seeds. A significant differentiation of the effect of the extracts on vitality and healthiness of seeds was demonstrated depending on the origin of the extract (plant species), the way it was prepared and an interaction between these factors. The germination viability of seeds of brewing barley was influenced mostly by infusions from fruits of Coriandrum sativum, from seeds of Linum usitatissimum, from bark of Quercus robur, from roots of Levisticum officinale, from roots of Arctium lappa and from flowers of Verbascum thapsiforme. The most favourable activity on germination capacity was revealed using the infusions from seeds of L. usita- tissimum, from roots of A. lappa, from fruits of C. sativum and macerations from roots of A. lappa, from fruits of C. sativum and from bark of Q. robur. The infestation of seeds by microflora was reduced by macerations from leaves of Betula verrucosa, from seeds of L. usitatissimum, from fruits of Juniperus communis, and infusions from flowers of Crataegus oxyacantha, from seeds of L. usitatissimum, from leaves of B. verrucosa. The most favourable impact on viability of the seeds of common barley was revealed for infusions from roots of L. officinale, from stig- mas of Zea mays, from flowers of C. oxyacantha and macerations from flowers of Lavandula vera, from leaves of Mentha piperita and from roots of L. officinale. A positive effect on the germination capacity was exerted by infusions from the stigmas of Z. mays, from flowers of C. oxyacantha, from rhizomes of Acorus calamus, from bark of Frangula alnus, and macerations from bark of F. alnus, from leaves of M. piperita, from flowers of C. oxyacantha and from herb of Marrubium vulgare. The contamination of the seeds by microflora was reduced most effectively with infusions from young sprouts of Pinus sylvestris, from roots of Inula helenium, from leaves of Juglans regia, from herb of M. vulgare, from stigmas of Z. mays and macerations from rhizomes of A. calamus, from herb of M. vulgare, from leaves of J. regia, from seeds of L. usitatissimum and from flowers of L. vera.

DILL (ANETHUM GRAVEOLENS L.) SEED STALK ARCHITECTURE AND SEEDS INFESTATION WITH FUNGI

In the years 2002-2004 seeds of dill 'Amat' harvested from four different umbel position were evaluated for their infestation with fungi. On the tested seeds Alternaria alternata, Cladosporium spp., Epicoccum purpurascens, Gonatobotrys simplex and Trichothecium roseum were occurring the most frequently. The seed stalk architecture influenced infestation of disinfected seeds with A. alternata and non-disinfected seeds with Cladosporium spp.

REDUCTION OF FUNGI AND MYCOTOXINS FORMATION IN SEEDS BY GAMMA‐RADIATION

ABSTRACT Ninety samples of maize, chick‐peas and groundnut seeds collected from the Egyptian market were found to be heavily contaminated by molds. Alternaria, Aspergillus, Cladosporium, Eurotium, Fusarium, Mucor, Penicillium and Rhizopus were the most common fungal genera isolated from nondisinfected seeds. Aspergillus alutaceus, A. flavus, Fusarium verticillioides and F. oxysporum were isolated from all surface‐disinfected seeds and were reported to produce ochratoxin A, aflatoxin B1 and zearalenone, respectively. Irradiation at a dose 4.0 kGy reduced the mold growth greatly relative to unirradiated controls. There was no growth at dose 5.0 kGy. On the basis of the radiation survival data, the decimal reduction values D10 for A. alutaceus, A. flavus and F. verticilliodies were 0.70. 2.10 and 0.93 kGy in maize. A dose of 5 kGy inhibited the toxigenic molds and mycotoxin formation in seeds. Aflatoxin B1 and ochratoxin A were detected in maize and chick‐peas, whereas zearalenone was detected in maize samples. Application of radiation at a dose of 6.0 kGy detoxified aflatoxin B1 by 74.3–76.7%, ochratoxin A by 51.3–96.2% and zearalenone by about 78%.

Relationships between seed germination, fumonisin content, and Fusarium verticillioides infection in selected maize samples from different regions of Costa Rica

Thirty‐five maize seed samples from three geographic regions of Costa Rica were analysed for fumonisin content, germinability, and Fusarium verticillioides infection with and without surface disinfection. The concentration of fumonisins in the maize samples varied from 4 ng g−1 to 16 000 ng g−1 with an all over‐all average of 2500 ng g−1. There was a significant difference in fumonisin content between samples from Alajuela and Guanacaste. Germination of the seed samples ranged from 12% to 98% with significant differences between regions. F. verticillioides infection was 12–98% and 13–97% for surface‐disinfected and nondisinfected seeds, respectively. There was a significant negative correlation (r = ‐0.52) between fumonisin content and seed germination, but no significant correlation was found between fumonisin content and F. verticillioides infection, or between F. verticillioides infection and seed germination. Most of the high fumonisin seed samples had some mechanical or insect damage. Whether or not the fumonisins had a direct effect on germination was not further established. It is concluded that the large differences in fumonisin content of maize seeds within and between regions are primarily caused by differences in seed quality, genetic diversity of F. verticillioides strains in natural populations, climatic differences between regions, and varietal differences. Some of the fumonisin levels found in this study coincide with levels associated with risks to humans and animals in other countries.

Fungal Flora of Barley Seeds in Saudi Arabia and Its Control

Twenty-nine species of fungi were isolated from normal and discolored seeds of barley. More species were isolated from discolored seeds and percentage of occurrence of individual fungi was higher in nondisinfected seeds as compared to disinfected seeds. The most common genera found were Ulocladium (four species); Alternaria, Aspergillus, and Drechslera (three species); Curvularia, Fusarium, Mucor, Penicillium, and Syncephalastrum (two species). Diathane was found to be most effective among fungicides tested.

Efficacy of Certain Fungicides and Antibiotics on Seed Mycoflora of Rice

Twenty-six fungi in all were isolated from the non-disinfected seeds, surface-disinfec- ted seeds and from the cotyledons of rice variety IEI 1991 by agar-plate method and blotter technique. Choanephora cucurbitarum. Humicola grizee, Mortierella subtilissima, Papu- laspora sp. and Trichothecium roseum are the new records as seed-borne fungi on this seed. Soods were treated with fifteen organic and inorganic fungicides and five antibiotics (antifungal and antibacterial) in different concentrations at the rate of 0.1, 0.2, 0.3 per cent of seed weight and 50, 100 and 200 ppm respectively and it was observed that Agaliel '3' at 0.3 per cent and Agrimycin-17 at 200 ppm checked several fungi considerably and enhanced per cent seed germination.