Fertilizing the Flame: Effects of AB Fertilizer Concentration on Vegetative Growth, Fruit Yield, and Capsaicin Biosynthesis in Capsicum frutescens

Abstract

The Capsicum crops, known for their diverse phytochemical composition and pungency, are significantly influenced by agricultural practices. This study presents research on the 'cili padi' variety of Capsicum frutescens, a relatively unexplored species, grown hydroponically on a cocopeat medium using a high-quality AB fertilizer with varied nutrient concentrations. The research focused on analysing plant growth patterns, fruit yield, and capsaicinoid levels throughout the growth cycle. This involved detailed morphological measurements, productivity assessments, and the use of cyclic voltammetry for capsaicinoid quantification. The findings revealed that vegetation growth, yield, and metabolite parameters were closely linked to fertilizer concentration. Notably, an increase in nutrient availability led to improvements in plant growth metrics, fruit yield, and capsaicin levels. However, these benefits peaked within a specific fertilizer concentration range (1.5-2.1 E.C.-mS/cm) before declining, indicating the existence of toxicity thresholds. The study highlights the critical importance of balanced fertilization in hydroponic cultivation of C. frutescens, as it simultaneously enhances productivity and pungency quality. Interestingly, the research uncovered a threshold in nutrient concentration that optimizes nitrate conversion into capsaicin, beyond which overall plant growth continues to increase with higher fertilizer quantities. This finding necessitates further investigation into the metabolic and transport pathways that limit phytochemical production in these plants. Additionally, the capsaicinoid concentrations achieved in this study resulted in only moderately pungent Scoville ratings, suggesting a variance in biosynthetic capacity between this specific local species and more commonly studied pepper types. In summary, this research underscores the importance of a well-calibrated fertilization strategy to effectively boost both yield and pungency quality in C.frutescens . The insights gained from this study contribute significantly to our understanding of optimal hydroponic cultivation practices for enhancing the desirable traits of this unique chili variety.