o:6758 UTICAJ pH VREDNOSTI HRANLJIVOG SUBSTRATA NA MORFOLOŠKE I PATOGENE ODLIKE FUSARIUM OXYSPORUM VAR. ORTHOCERAS FORMA PINI, SA OSVRTOM NA ENCIMA SISTEM INFLUENCE OF THE pH VALUE OF THE NUTRITIOUS MEDIUM ON THE MORPHOLOGIC AND PATOGENIC CHARACTERISTICS OF FUSARIM OXYSPORUM VAR. ORTHOCERAS F. PINI, WITH REFERENCE TO THE ENZYMATIC SYSTEM sr The fungus Fusarium oxysporum S c h l e c h t. emend. Snyder et Hans. var. orthoceras (A p p. et W r.) B i l a i comb. nova f. pini, isolated from the rhysosphere and roots of the layed down black pine seedlings iln the Institute's nursery in Sremčica, was grown ,,in vitro" on a nutritious medium of different, inicial unbuffered pH values of 2-10. It was notliced that the fungus was developing on the mentioned pH values of the medium. At the end of the observation period there occured the neutralization and alcalization of the nutritious medium of the inicial pH values 2-8,5, except in the case of the pH value 10, when a slight dealcalization of the medium took place. In all situations the fungus has shown the basic morphologic characteristics and demonstrated pathogenic properties, causing embryo and radicel decay and sapling laying down. In enzymatic activity the following hydrolytic enzymes were established: cellulase, amylase, protopectinase, gelatinase and peptidase, as well as the oxidative- reductive ones: phenoloxydase, glucose aerodehydrogenase, nitrate and other reductase. It comes out from the above results that the fungus, by its physiological activities, has provided an apsolute pathogenic potential. It represents a continuous danger for black pilne seeds and saplings, demanding a constant application of preventive measures in seedling production in the nurseries. 2024-12-24T12:51:15.382Z 44 yes 46 Vera Plavšić application/pdf 6508726 https://unilib.phaidrabg.rs/o:6758 no yes 1 70 92000001 1984 71A07 Zbornik radova Instituta za šumarstvo 22-23 19 37 Institut za šumarstvo 1984