Effect of natural biostimulants on yield and nutritional quality: an example of sweet yellow pepper (Capsicum annuum L.) plants.

Background: Modifications in growing techniques can affect the yield and nutritional quality of various cultivated plant species. Owing to its high nutritional value, pepper (Capsicum annuum L.) was used in this study as a model plant to investigate the effect of natural biostimulants on yield and fruit quality parameters under conditions of reduced fertilisation.

Results: A positive influence of biostimulant treatment on yield parameters was observed. The overall increase in the pigment content of leaves after biostimulant application agreed well with the higher total and commercial yields of treated pepper cultivars compared with their controls. The results showed that natural biostimulants had a positive effect on the vitamin C and total phenolic contents in pepper fruits during the hot summer season. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) antioxidant activities were also significantly higher (P < 0.05) in treated plants and correlated strongly with all measured quality parameters except total phenolic content.

Conclusion: Generally, biostimulants improved the antioxidant activity, vitamin C and phenolic contents in fruits as well as the pigment content in leaves of treated compared with non-treated pepper plants grown hydroponically. Thus the application of biostimulants could be considered as a good production strategy for obtaining high yields of nutritionally valuable vegetables with lower impact on the environment.