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Species of the genus Alternaria are significant wheat contaminants during production, transport and storage, requiring biocontrol measures which typically rely on the bacteria from the Bacillus genera. As these are among the most beneficial and exploited biocontrol agents, in this study, the inhibitory activity of indigenous Bacillus spp. was as­sessed against the Alternaria alternata isolate originating from the wheat seed. Two of the fifteen Bacillus s pp. i ncluded i n t he s tudy s howed t he i nhibitory effect. Specifically, 25.0−55.0% inhibition of A. alternata growth was achieved when the isolate coded as NB11 was applied in 106−109 cells mL-1 concentrations. On the other hand, when applied in 107−109 cells mL-1 concentrations, the isolate coded as NB16 inhibited A. alternata growth by 35.2−51.1%, but was ineffective at lower concentrations. Thus, these in vitro assays indicate that both Bacillus spp. (NB11 and NB16) isolated from the wheat rhizosphere can be applied in practice in the control of A. alternata.

The present study focused on detecting bacteria of the Xanthomonas spp. complex (X. euvesicatoria, X. vesicatoria, X. perforans and X. gardneri) and examining their influence on certain quality parameters of pepper seed collected from the territory of Smederevska Palanka (Serbia). The analysis included 27 non-commercial pepper seed genotypes (including chili and sweet pepper) collected in 2021. Several parameters of the quality of analyzed pepper seed (germination energy, total germination, moisture and seed health) were determined. The results showed that out of a total of 27 analyzed samples of pepper seed, the presence of X. euvesicatoria was detected in 13 of them. The presence of X. vesicatoria, X. gardneri and X. perforans was not confirmed. Germination energy of infected seed was 52-84%, and of bacteria-free seed 63-90%; total germination of infected seed was 66-91%, and of bacteria-free seed 80-95%. Seed moisture of infected seed samples was 6.1-12%, and of bacteria-free seed 6.2-8.1%. These parameters did not show significant statistical difference (p>0.05). The presence of seed-borne fungi Fusarium sp. accounted for up to 3% in 25 samples, while it was up to 6% in the remaining two; Alternaria sp. ranked from 1-4% in 25 samples, and up to 5% in only two samples. The results led to a conclusion that the bacterium X. euvesicatoria is the predominant pathogen of the Xanthomonas spp. complex, but it did not affect the quality parameters of the tested pepper seed.