## 3 Results and Discussion
### Antifungal Activity of Calendula officinalis Water Extract In Vitro
#### 3.3.2 Influence of _Calendula officinalis_ Water Extract on Fungal Biomass Production  
There was a significant inhibition of _A. niger_ biomass production after 7 days of incubation when 15% and 10% _Calendula officinalis_ water extract were added to the culture medium. The reduction in pathogen biomass was 15.50% and 9.17%, respectively. On the other hand, as in the previous experiment on Petri dishes, the study extract did not significantly affect the inhibition of _Penicillium_ sp. biomass production.  
Studies on the inhibitory effect of plant extract on the growth of pathogenic fungi biomass have been reported by some researchers. [PERSON] et al. [40] evaluated the potential of water extracts of _Partheinum hysterophorus_, a plant in the _Asteraceae_ family, against three pathogenic fungi: _Drechslera tetranera_, _Phoma glomerata_, and _A. niger_. The lower extract concentrations proposed in the experiment caused a decrease in fungal biomass production,  
Figure 1: Effect of adding _Calendula officinalis_ water extract on the mycelial growth of _Aspergillus niger_. N15, N10, N5—addition of _Calendula officinalis_ water extract to the medium in doses of 15%, 10%, and 5% (\(v/v\)), respectively; Values marked with the same letters do not differ significantly at \(p<0.05\) ([PERSON]’s post hoc test); mean value (\(n=3\)) \(\pm\) SD.  
Figure 2: Effect of adding _Calendula officinalis_ water extract on the mycelial growth of _Penicillium_ sp. N15, N10, N5—addition of _Calendula officinalis_ water extract to the medium in doses of 15%, 10%, and 5% (\(v/v\)), respectively; Negative values denote stimulation of fungal biomass production; Values marked with the same letters do not differ significantly at \(p<0.05\) ([PERSON]’s post hoc test); mean value (\(n=3\)) \(\pm\) SD.  
and this response was species-specific. In contrast, increasing extract concentrations increased fungal biomass production at all harvest intervals. [PERSON] and [PERSON] [20] showed that water extracts of walnut (_Iqglans regia_) leaves, birch (_Betula verrucosa Elrh._) bark, and nettle (_Ulrica dioica_ L.) herb strongly reduced the biomass production of _Fusarium culmororum_ (29.60-53.70%) and _Botrytis cinerea_ (17.90-53.80%), while in some variants of the experiment tested extracts showed a stimulating effect on the biomass growth of _Alternaria alternata_, _Phoma exiqua_, and _Sclerotina sclerootinum_. [PERSON] and [PERSON] [41] tested the antifungal activity of _Moringa oleifera_ Lam. seed oil and extract against _Fusarium oxysporum_, _F. solani, Alternaria solani, A. alternate_, _Rhizoctonia solani, Sclerotium rolfsii_ and _Macrophonina phaseolina_, and the researchers showed that study oil and extract had an inhibitory effect on the growth of pathogen biomass.  
The results presented in the paper and reports by other researchers indicate that a particular plant extract can reduce the biomass production of one pathogen and have no effect or even stimulate the growth of another. Therefore, testing a broad spectrum of product-specific microorganisms is appropriate when designing new foods with plant extracts. This will make it possible to create foods of high quality and high safety for the consumer.