Effects of selected biostimulants on qualitative and quantitative parameters of nine cultivars of the genus Capsicum spp.

Despite the growing popularity of biostimulants among farmers, a major problem remains with their variable effects on individual species and varieties of cultivated crops. Therefore, it is important to know how to choose a suitable product for the given growing conditions while simultaneously considering species and varietal variability in crop cultivation. The goal of this study is to highlight different reactions of plants to the applied preparations within the monitored representatives of the Capsicum genus, with an emphasis on intervarietal variability. The experiments with two monitored and one control variants occurred during the growing seasons of 2020 and 2022 in Slovakia’s southwest region, characterized by a European continental climate with warm and dry summers. Seven varieties of Capsicum annuum and two varieties of Capsicum chinense were chosen based on actual growers’ preferences: “Žitava,” “Szegedi 80,” “Karkulka,” “Hodoníska sladká,” “Habanero Orange,” “Habanero Chocolate,” “Kristián,” “Damián” and “Kurtovska kápia.” In the present study, we observed the effects of selected commercial biostimulants – the combination of Energen Fulhum Plus and Energen Fruktus Plus in the first variant and the biostimulant Humix® Universal in the second variant – on bell pepper fruits. We evaluated three productivity parameters: fresh fruit weight per variety, weight of one fruit and number of bell pepper fruits per plant. From the qualitative parameters, we evaluated the content of ascorbic acid, capsaicin, carotenoids, and the American Spice Trade Association color value. The monitored biostimulants had variable effects in all pepper varieties, while some of them statistically significantly increased and others significantly decreased the monitored parameters. In conclusion, we state that the application of verified biostimulants did not have a uniform effect on the observed varieties of the Capsicum genus. Therefore, based on our results, we cannot generalize the effect of a specific biostimulant on a specific crop genus or species.