Effect of biostimulants on the growth, yield and nutritional value of Capsicum annuum grown in an unheated plastic tunnel

Abstract Recent years have witnessed an increased interest in the cultivation and consumption of peppers. Therefore, new solutions are being sought to provide pepper plants with the most favorable conditions for growth and development. In view of the above, the aim of this study was to evaluate the effect of selected biostimulants on the biometric parameters, yield and nutritional value of Capsicum annuum fruit. The research hypothesis postulates that biostimulants can increase the yield and improve the nutritional quality of pepper fruit. The experiment was conducted in an unheated plastic tunnel. The experimental materials comprised three sweet (‘Solario F1’, ‘Turbine F1’ and ‘Whitney F1’) and two hot (‘Cyklon’ and ‘Palivec’) cultivars of C. annuum. It was found that the combined application of environmentally-friendly microbial-based biostimulants (BB Soil, BB Foliar, Multical, MK5 and Biocin F) did not clearly improve the morphological traits of pepper fruit, yield or the concentrations of sugars and organic acids in fruit, therefore their use is not economically justified. Hot peppers had a higher content of dry matter, total sugars and L-ascorbic acid than sweet peppers. The analyzed biostimulants increased nitrate (V) concentrations in the fruit of both hot and sweet peppers. ‘Turbine F1’ and ‘Solario F1’ were particularly prone to nitrate (V) accumulation in fruit, therefore the use of biostimulants should be limited in their cultivation. Pepper fruits with the largest horizontal diameter and the thickest skin should be preferred because these traits are associated with high sugar content