The effects of UV-C radiation on the germination rate and fungal contamination of tall fescue seeds were investigated. Samples from the same seed lot were irradiated in two different ways in two consecutive years. The seeds were irradiated with a Hg vapour lamp using different doses. In the first trial one side of the seeds was irradiated, while in the second trial a mirror was used to irradiate the whole seed surface. The results showed that various doses of UV-C irradiation had an effect on the germination rate, but there were no significant differences in germination percentage between the treatments. Differences in fungal contamination rates were observed when the seeds were irradiated on all sides. The presence of 21 fungal genera was identified on the seeds, the saprotrophic fungi
Authors:R. Kiss, J. Sonkoly, P. Török, B. Tóthmérész, B. Deák, K. Tóth, K. Lukács, L. Godó, A. Kelemen, T. Miglécz, Sz. Radócz, E. Tóth, N. Balogh, and O. Valkó
Covell , S. , Ellis , R. H. , Roberts , E. H. and Summerfield , R. J. ( 1986 ): The influence of temperature on seed germinationrate in grain legumes: I. A comparison of chickpea, lentil, soybean and cowpea at constant temperatures . – J. Exp
Authors:Fruzsina Bakti, Anita Király, Erzsébet Orosz, Márton Miskei, Tamás Emri, Éva Leiter, and István Pócsi
Determination of germinationrates in submerged liquid cultures
To determine germinationrates, 10 8 freshly grown conidia were inoculated into 100 ml MNM without any nutritional supplements, or supplemented with 10 mmol l −1 GSH or the mixture of 20
Authors:S. Aboling, M. Sternberg, A. Perevolotsky, and J. Kigel
The relationship between the soil seed bank at the onset of the growing season and the structure of the ensuing vegetation under grazing was investigated in an eastern Mediterranean grassland. Species responses to two contrasting cattle grazing regimes were studied through plant trait analyses. Traits included plant size, phenology, seed size and germination fraction. Changes in species composition of the soil seed bank and the vegetation were analyzed using a plant functional group approach. The results showed that seed bank and relative cover of tall annual and perennial grasses increased when grazed late in the growing season. The opposite was noted for short annual grasses, annual legumes, annual thistles, annual crucifers and other annual forbs. Grazing treatments little affected plant cover of herbaceous perennials. Tall annual and tall perennial grasses have large seeds and germination rates over 90%. Short annual grasses showed similarly high germination rates but with smaller seeds. Annual legumes were characterized by medium size seeds and lower germination fractions (<50%). Tall annual grasses showed high competition capabilities at late grazed paddocks due to a combination of regeneration traits that included: high germination fraction, larger seed and seedling size, and inflorescence with morphological defenses. It is proposed that in addition to plant size and palatability, regeneration traits such as seed dormancy, seed and seedling size play an important role in determining the vegetation structure under different grazing regimes, thus contributing to the high plant species diversity characteristic to Mediterranean grasslands.
Pathogenic variation was studied in 16 fungal isolates of four Fusarium head blight (FHB) species on two modern Syrian bread and durum wheat cultivars using an in vitro Petri-dish test. Three aggressiveness criteria: germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction were evaluated. Regarding AUDPCstandard, intra- and inter-species variability in aggressiveness was detected. The other two aggressiveness criteria did not distinguish fungal isolates within and among species. It seems that AUDPCstandard may be used to measure aggressiveness of FHB on wheat at early stages. The three aggressiveness parameters were not significantly correlated. Cultivar-specific aggressiveness has not been detected. It was not possible to cluster the isolates based on their species origins because of similarity in pathogenic level among the 16 fungal isolates. Bread wheat was more resistant to FHB infection than durum wheat in vitro. The two tested modern cultivars were shown to exhibit moderate to high FHB resistance levels.
Germinated brown rice received great attention as healthy ingredient and can be used as an alternative source in the malting and brewing industry. The germination capacity, physico-nutritional properties, sugars, and diastase enzyme activity of brown rice affected by germination times and temperature were determined and compared with control. Soaking in water increased the moisture content of brown rice. Germination rate of brown rice was also increased by higher germination time and temperature and reached maximum after 48 h of germination at 35 ºC. However, dry matter loss, grain weight, and density are affected to a lesser extent. Germination significantly (P<0.05) affects the crude protein, fat, fibre, and ash contents. Total carbohydrates content showed linear relationship with germination time and temperature. During germination, hydrolytic enzymes act on starch, reducing its concentration and resulting in higher total and reducing sugars amounts. Increase in germination time and temperature also increased diastase enzyme activity.
The interaction between bread wheat (Triticum aestivum L.) plants and four filamentous species of the Fusarium genus (the causal agent of Fusarium head blight, FHB) was analyzed in an in vitro Petri-dish assay. Pathogenicity criteria as well as germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction were investigated in seeds and six-day-old seedlings showing a moderately level of quantitative resistance, after inoculations with 16 FHB isolates. AUDPCstandard did differentiate FHB isolates and the other two pathogenicity criteria did not. It was not possible to cluster the isolates based on their species origins because of similarity in pathogenic level among the 16 fungal isolates. Cultivar-specific pathogenicity has been detected. The values of disease incidence and disease severity involved in previous artificial head and floret inoculations showed significant correlation with AUDPCstandard: r=0.653** and r=0.559*, respectively. AUDPCstandard could be of potential use in evaluating the pathogenicity of FHB in adult wheat plants.
Salinity is one of the major abiotic stress factors affecting series of morphological, physiological, metabolic and molecular changes in plant growth. The effect of different concentrations (0, 25, 50, 100 and 150 mM) of NaCl on the vegetative growth and some physiological parameters of karkade (Hibiscus sabdariffa var. sabdariffa) seedling were investigated. NaCl affected the germination rate, delayed emergence and retarded vegetative growth of seedlings. The length of seedling as well as the leaf area was significantly reduced. The fresh weight remained lower in NaCl treated seedlings compared to control. NaCl at 100 and 150 mM concentrations had significant effect on the dry matter contents of the treated seedlings. The chloroplast pigments in the treated seedlings were affected, suggesting that the NaCl had a significant effect on the chlorophyll and carotenoid biosynthesis. The results showed that the salt treatments induced an increase in proline concentration of the seedlings. The osmotic potential (ψs) of NaCl treated seedlings decreased with increasing NaCl concentrations. Salt treatments resulted in dramatic quantitative reduction in the total sterol percent compared with control ones. Salt stress resulted in increase and decrease of Na+ and K+ ions, respectively. NaCl salinity increased lipid peroxidation. SDS-PAGE was used to evaluate protein pattern after applying salt stress. High molecular weight proteins were intensified, while low molecular weight proteins were faint. NaCl at 100 and 150 mM concentration distinguished with new protein bands. Salt stress induced a new peroxidase bands and increased the band intensity, indicating the protective role of peroxidase enzyme.
Fens are among the most threatened habitats in Europe as their area has decreased considerably in the last centuries. For successful management and restoration conservationists need detailed knowledge about seed bank formation and seed longevity of plants, as these features are closely related to successional and vegetation dynamical processes. I analysed seed longevity and the germination characteristics of six fen plant species by seed burial experiments. Based on seed weight, seed bank was expected for long-term persistent for the light-seeded Schoenus nigricans, Carex appropinquata, C. pseudocyperus, C. davalliana and Peucedanum palustre and also that for the medium-seeded Cicuta virosa. It was proved that, the latter two species have short-term persistent seed banks, while Carex pseudocyperus has a transient seed bank, therefore these species may only have a limited role in restoration from seed banks. It was found that Schoenus nigricans, Carex appropinquata and C. davalliana have persistent seed banks, because some of their four-year-old seeds have emerged. Fresh seeds had low germination rate in all studied species and majority of seeds emerged after winter, except for Carex pseudocyperus. After the germination peak in spring, the majority of the ungerminated seeds of Schoenus nigricans, Peucedanum palustre, Carex appropinquata, C. davalliana and Cicuta virosa entered a secondary dormancy phase that was broken in autumn. I found the seasonal emergence of the latter three species highly similar.
Seed samples of four Egyptian broad bean cultivars were tested for seed-borne fungi. The deep freezing method was used to isolate twelve seed-borne fungi viz., Alternaria alternata, Aspergillus flavus, A. niger, Botrytis fabae, Cladosporium cladosporioides, Fusarium oxysporum, F. solani,, Penicillium italicum, Rhizoctonia solani, Rhizopus stolonifer, Stemphylium globuliferum and Trichothecium roseum from the broad bean cultivars viz., Giza 3, Giza 429, Giza 843 and Misr 1. Aspergillus flavus, Botrytis fabae, Fusarium oxysporum and Penicillium italicum were the most predominant fungal species. Aqueous extracts from five wild medicinal plants (Asclepias sinaica, Farsetia aegyptia, Hypericum sinaicum, Phagnalon sinaicum, and Salvia aegyptiaca) which were collected from the Sinai Peninsula, Egypt were tested against the predominant fungal pathogens. All the aqueous plant extracts significantly inhibited the mycelial growth of these fungi, but the extract of Asclepias sinaica exhibited the strongest antifungal activity. The maximum seed germination rate was observed in infested Giza 843 and minimum in Misr 1. Treating seeds with plant extract of Asclepias sinaica (10%) enhanced the percentage of seed germination of all cultivars in both laboratory and pot experiments. Maximum root and shoot lengths of seedlings were recorded in Giza 843 during fungal infestation or treatment by plant extract. In greenhouse experiment, the aqueous A. sinaica extract reduced disease severity and total pigments but increased total phenolics and fruit yield.