Effect of NPK fertilizer on the growth of saprophytic fungi in alluvial soil: uticaj NPK dubriva na razvoj saprofitnih gljiva u aluvijumu

The influence of different NPK fertilizer rates on the developement of the saprophytic fungi of the alluvial soil planted with plum culture has been studied over the three-year period (2003-2005). The trial was set up in the experimental plum orchard established by Fruit Research Institute Cacak (Serbia) and at the laboratory of Department of Microbiology, Faculty of Agronomy Cacak (Serbia). The soil was treated with 8:16:24 + 3% of MgO mineral fertilizer in the following treatment variants: variant [N.sub.1]-400 [kgha.sup.-1]; variant [N.sub.2]-600 [kgha.sup.-1]; variant [N.sub.3]-800 [kgha.sup.-1] and variant [N.sub.4]-1000 [kgha.sup.-1], all treatment variants being applied in three replications. Unfertilized soil served as the control. The size of the trial plot was 68 [m.sup.2]. The effect of the studied mineral fertilizer rates was determined three times over the growing season. It was checked by identification of the number of saprophytic fungi by the indirect rarefaction method on Czapek nutritive medium. The results of the study suggested that the number of the saprophytic fungi varied by different fertilizer rates, periods of sampling and years of study. The application of fertilizers brought about increase in the number of the saprophytic fungi. Of all studied treatment variants, the one with highest nitrogen rate (variant [N.sub.4]) exhibited the strongest effect. The influence of the applied fertilizer was highest over the third sampling period. Furthermore, the effect thereof was highest in 2003. The application of 600 [kgha.sup.-1] of mineral fertilizer resulted in the highest plum yield.