Foliar biostimulant from Kappaphycus alvarezii enhances growth and development of peppermint plants (Mentha × piperita)

This study aimed to evaluate the morphophysiological and biochemical effects of foliar application of Kappaphycus alvarezii aqueous extracts in the development of peppermint (Mentha × piperita) plants grown in a greenhouse in Brazil. Extracts at concentrations of 1%, 3%, 5%, and 7% (v/v) produced in São Paulo state (Kal-SP, southeastern Brazil) and Santa Catarina state (Kal-SC, southern Brazil) were utilized. Morphological and biochemical responses exhibited a dose-dependent relationship, with distinct responses according to the investigated variables. For plant height, the highest averages were recorded with 5% Kal-SP and 1% and 7% Kal-SC, while 7% Kal-SP and 7% Kal-SC showed the highest number of nodes. Additionally, 7% Kal-SP and 1% and 3% Kal-SC produced the greatest aerial biomass. Biochemically, the algal biostimulant at 1% was the most effective in increasing the contents of total soluble sugars (Kal-SC), total starch ( Kal-SP and Kal-SC), total carbohydrates ( – Kal-SC), total protein (Kal-SP), total amino acids , and total flavonoid contents (both Kal). Furthermore, the aqueous extracts of K. alvarezii also modulated the biogenic amine contents of peppermint plants. Taken together, the findings demonstrated the potential of the algal biostimulant to enhance plant development and increase beneficial biochemical compounds in peppermint, suggesting its applicability in agricultural practices aiming at improving crop quality and yield.