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The increasing usage of chemicals for plant protection in recent years has become a serious problem. One of the possible solutions is use of beneficial microorganisms instead of synthetic fungicides, which will contribute to the protection of the environment and human health. Since the fungi Aspergillus flavus and Fusarium graminearum are the most important pathogens that cause maize diseases and produce mycotoxins, the potential of Trichoderma harzianum for biocontrol of both phytopathogens was examined in this paper. The aim of this paper was to study the influence of different carbon and nitrogen combinations in the medium for T. harzianum production. T. harzianum was cultivated in Erlenmeyer flasks and the effect of cultivation broth against selected maize pathogens was tested using well diffusion method. The results of this study showed that the combination of different carbon and nitrogen sources in the T. harzianum cultivation medium statistically significantly affects the production of Trichoderma cultivation broth effective on two tested phytopathogens. Dextrose as a carbon source and soybean flour as a nitrogen source proved to be the best combination in the medium for production of T. harzianum cultivation broth effective on A. flavus and F. graminearum. Maximal inhibition zone diameters of 31 mm and 56.33 mm were registered in those medium formulations for A. flavus and F. graminearum, respectively. These researches represent an important step for further research in which a medium of low market value would be selected. This would reduce the price of the production process but also the final product.

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Bacillus species are promising producers of various compounds that have pronounced antimicrobial, antiviral and antitumor activities. Due to its GRAS status, Bacillus subtilis represents an excellent candidate for the usage in plant pathogens biocontrol. In this research, evaluation of antifungal metabolites biosynthesis by Bacillus subtilis ATCC 6633 and optimization of glycerol-based medium composition, using response surface methodology, for the production of compounds effective against Neurospora crassa were investigated. The results of disc-diffusion method indicate that applied Bacillus strain produces compounds with antifungal activity against tested fungus. In order to find optimal cultivation medium composition, the experiments were carried out in accordance with Box-Behnken design, and optimization was performed using the concept of desirability function combined with previously defined mathematical equation, which describes examined bioprocess. The optimization model predicts that maximum inhibition zone diameter against Neurospora crassa of 32.24 mm is achieved when initial content of glycerol, NaNO 2 and K 2 HPO 4 were 49.68 g/L, 2.90 g/L and 6.49 g/L, respectively. Additionally, the second optimization set was made to minimize the consumption of medium components and costs of medium preparation. The obtained results are the basis for further research aimed to develop medium appropriate for economically justified production of bioactive compounds at industrial scale.

The phenomenon of genotype by environment interaction (GEI) represents permanent interest for breeders, geneticists and biometricians with its practical and theoretical aspects. We investigated GEI for grain yield of medium early maturity maize (Zea mays L.) hybrids from the official variety trial network by the Department of Protection and Recognition of Varieties of the Republic of Serbia that includes experimental maize hybrids on eight sites over two years. Environmental variables explained 77.6% and 60.7% of the GEI variation for two consecutive years, respectively. Factorial regression combined with stepwise procedure revealed the model which includes variables precipitation in July (pr7), minimum temperature in May (mnt5), maximum temperature in May (mxt5) and insolation hours in April (sh4), in 2004, and environmental index (EI) and average temperature in September (mt9) in 2005, to be the most explanatory models in the region of Vojvodina (Serbia) in two consecutive years. These results provide a base for further research in GEI and stability analysis, and are a useful tool in characterizing the sub-regions of maize growing area and extending the existing results to new sites. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 451-03-68/2020-14/200032]