Several expressions of severity of leaf area infected by powdery mildew, Erysihpe graminis f. sp. hordei, were regressed on predictor variables, date of observation, growth stage of plant after Feekes, and the 7 day sums of meteorological data either before the date of observation or preceding 7 day the date of observation in spring barley. Development of epidemic better coincided with the sums of meteorological data preceding the date of observation probably due to greater influence of environmental factors before infection than during latent period of disease. We ascertained significant positive influence of date of observation, growth stage of plants and temperature, and adverse influence of sunshine within the course of epidemic. In general, the development was successfully predicted only for severity expressions with Gompertz transformations providing efficient straightening of the course of epidemic. Predictive regressions based on temperature, sunshine, and the development stage of plant were developed. Regressions differed both in significance and in necessary number of predictors according to description of infected area. Gompertz transformation of proportion of leaf area infected by powdery mildew fluffs and necrosis related to field resistance of host plant, was indicated as the best predictable value. The transformation enabled to specify a simple and highly significant linear model regressing powdery mildew occurrence only on 7 days sum of day degrees preceding 7 days the date of observation. Possibilities of further precisions of prediction equations are discussed. It is suggested that more detail analysis of phenomenons underlying regressed variables and more detailed records of environmental predictors may enhance the significance of predictions.
By inoculation of selected symbiotic microorganisms (Rhizobium bacteria, VA-mycorrhizal fungi) the growth of peas was increased under temperate climates on different field sites.Effective Rhizobium bacteria increased the dry matter yield at flowering of 0.21 t/ha, that was 7.7 % (average of 6 experiments). The com yield was increased in average of 32 field experiments of 0. 2 t/ha (5,6 %) and in 52 practise experiments in agricultural farms of 0.41 t/ha (16 %).VA-mycorrhizal fungi affected the nodulation of the Rhizobium indigenous population, encouraged the mineral nutrition (P, K, Mg) and reduced the root infection with pathogens.A combined inoculation of Rhizobium bacteria and VA-mycorrhizal fungi did not lead to synergistic growth stimulations.To inoculate plants with Rhizobium bacteria the seed inoculation with peat preparates was carried out as the best way. The inoculation of mycorrhizal fungi was done with peat-bentonite-mixture preparates on the seeds or as granules in the seed row.
In a Pasteuria population found in pea cyst nematodes, Heterodera goettingiana, at Munster/Germany (HGP) the developmental cycle is similar to that in the three nematode-parasitic Pasteuria species described so far. In contrast to P. penetrans and P. nishizawae, however, infection takes place in the second-stage juveniles, in which also the whole developmental cycle is completed. Females or cysts of H. goettingiana were never found to be infected; in males spores attached to the cuticle were rarely observed. In comparison to the Pasteuria species parasitizing Meloidogyne resp. Heterodera elachista and other cyst nematodes, the reproduction rate of 500 spores/nematode is extremely low. Distinction of the different Pasteuria species or isolates by light microscopy is difficult. HGP spores show obvious morphological differences to P. thornei only which is parasitizing Pratylenchus.
The behaviour of Salmonella enteritidis during the Feta cheese making process was investigated. Two lots of pasteurized whole ewe's milk were inoculated to contain 10(6) cfu/ml of S. enteritidis (strain AS1 and AS2) and were processed into Feta cheese following standard procedures. All samples were examined for S. enteritidis both quantitavely and qualitatively, while moisture, fat, water activity and pH were also measured. S. enteritidis was enumerated in duplicate samples by surface plating on SS agar. Selected salmonella-like colonies were identified biochemically and serologically. The enumerations have shown that S. enteritidis was initially entrapped in the curd. Then the growth of S. enteritidis gradually decreased and no Salmonellae were quantitavely enumerated after the 23rd day. However S. enteritidis was detected qualitatively in samples taken until the 38th day.
The effect of potassium sorbate on the growth and penicillin acid production of Aspergillus ochraceus and Penicillium aurantiogriseum was studied. Yeast extract sucrose (YES) broth at initial pH values of 5.5 or 7.0, and containing different concentrations of potassium sorbate was inoculated with fungal spores and incubated for 35 days at 28 degrees C. In all cases, although the pH changes in sorbate-containing media were delayed, patterns were similar to those of the cultures without sorbate. This was most evident when the highest concentration of potassium sorbate was used. Potassium sorbate also inhibited mycelial growth. Penicillic acid production was initially delayed by the presence of potassium sorbate but this inhibition was eventually overcome (30-35 days) and penicillic acid levels at the end of the experiment were similar or higher then the controls. Generally cultures growing in culture media at an initial pH of 5.5 produced less toxin than those growing at pH 7.0.
Nitrification potential of five soils of north Kamataka viz., black soil, red soil, paddy soil, forest soil and a sodic soil amended with urea and ammonium sulphate (@ 4 mg NH+4-N 10 g-1 soil) was studied. Both the fertilizers significantly enhanced the nitrification potential of all the soils. Addition of urea enhanced nitrification potential significantly over addition of ammonium sulphate in all die soils except red soil. The lowest nitrification potential was recorded in forest soil irrespective of the addition of ammoniacal fertilizers. The change in nitrification potentials of soils with respect to physico-chemical properties are also discussed.
The effect of soil infection with F. oxysporum and/or R. solani on the rhizosphere microflora, growth, nodulation and nitrogen fixation of Rhizobium inoculated and uninoculated broad bean plants was studied. The obtained results generally, indicated that soil fungal infection reduced the numbers of total bacteria, actinomycetes and sporeformers in the rhizosphere soil of broad bean plants (either inoculated or uninoculated), comparing with those grown in the uninfected ones. However, total fungal counts were higher in the rhizosphere of Rhizobium inoculated or uninoculated plants grown in the pathogenic fungi infected soils than in the rhizosphere of those grown in the uninfected ones. In addition, the recorded numbers of formed nodules/plant, dry weight/plant (root and shoots) and nitrogen content of Rhizobium inoculated or uninoculated broad bean plants grown in fungi infected soils were generally lower than in those grown in uninfected ones. The lowest numbers of nodule/plant were found in those grown in F. oxysporum infected soil.The antagonistic effect of fungal culture filtrates of either F. oxysporum or R. solani towards the seven species of Rhizobium or Bradyrhizobium was studied. None of the seven species of Rhizobium or Bradyrhizobium was affected by R. solani culture filtrate. However, growth of five species were inhibited by culture filtrate of F. oxysporum. The highest inhibitory effect was recorded in case of R. leguminosarium.Several sporeforming bacteria and actinomycetes isolated from the rhizosphere of healthy broad bean plants were found to be antagonistic towards F. oxysporum or R. solani (in vitro). The application of highly antagonistic isolates of sporeformers or actinomycetes to fungi infected soils resulted in marked reduction in the percentage of diseased broad bean plants (in vivo).
The crude fibrinolytic enzyme preparation from Fusarium oxysporum N.R.C. 1 was purified into two enzymes by ammonium sulphate precipitation followed by chromatography on Sephadex G-100 and DEAE-cellulose. Both fibrinolytic enzymes were more active on human than on bovine fibrin. The activity of the ''major'' enzyme component on human fibrin was 72-fold that of the ''minor'' enzyme component. Both enzymes had the same temperature (37-degrees-C) and pH (6.98) optima. The ''minor'' enzyme component was more stable than the ''major'' one against heat and pH treatments. Both enzymes were significantly activated With Co2+ and inhibited with EDTA.
