Influence of the sources of carbon and nitrogen on morphological pathogenic characteristics of Fusarium oxysporum var. orthoceras f. pini

The influence of carbon and nitrogen sources on the morphological and pathogenic properties of the fungus Fusarium oxysporum var. orthoceras f. pini was investigated. An isolate of the fungus from rhizosphere and from the roots of lodged sprouts of black pine from the nursery in Sremcica was used as a test organism. The following substrates were used as carbon sources:arabinose, glucose, mannose, dextrose, sorbose, galactose, saccharose, lactose, maltose, starch, cellulose and pectin, and as nitrogen sources:K, Na and ammonium nitrate, asparaginic acid, alanine, glycine, tryptophane, methionine, peptone and gelatin. Each of the above C and N sources were added to the nutrient. On the basis of the obtained results the following is concluded: 1)The investigated fungus is capable of existing in various nutritive substrates. The character of morphological and pathogenic stability of the microorganism is shown then. Regardless of the substrate, the fungus retains the following structure components: formation of hyphae of coremium type, called "ribbons", numerous chlamydospores(mainly terminal, rarely intercalary), very numerous cylindric, uni-, rarely bi-cellular microconidia (on short stalks of single hyphae, as well as of hyphae within the ribbons) and single macroconidia (with 2 and 3 septa). 2)The fungus has always constant pathogenic properties. The dominant pathogenicity form "in vitro" is the moist rot of embryo with endosperm. The pathogen also causes the moist rot of the rootlet, cotyledons and, to a somewhat lower degree, causes lodging of the sprouts too. The fungus macerates certain tissue categories. Occurrence of colouring browning) of the infected tissues was noticed too. 3)Regarding the capability of using various substrates, the fungus is a great threat in the production of the coniferous seeding material.