Effects of Biostimulant Applications on Growth Performance, Chlorophyll Content and Biochemical Characteristics of Stinging Nettle (Urtica dioica L.) Microgreens

Abstract

This study evaluated the effects of selected plant-derived biostimulants on the emergence, growth, yield, chlorophyll content, antioxidant capacity, total phenolic content and colour characteristics of stinging nettle (Urtica dioica L.) microgreens grown under controlled conditions. Garlic, willow, wheat and banana peel extracts were applied as natural biostimulant treatments, while distilled water was used as the control. The experiment was conducted in a climate chamber using a randomised plot design with three replications. Time to 50% emergence, time to 100% emergence, microgreen height, stem diameter, individual fresh weight, total yield, SPAD chlorophyll value, total phenolic content, antioxidant capacity and L*, a*, b* and colour index values were determined. The treatments significantly affected most of the measured growth and quality parameters. Wheat extract resulted in the earliest 50% emergence and the highest chlorophyll content, reaching 52.66 SPAD units. Garlic extract produced the highest microgreen yield (581.3 g m⁻²) and also recorded the highest total phenolic content and antioxidant capacity, with 192.54 mg GAE g⁻¹ and 80.94 μmol TE g⁻¹, respectively. Willow extract was effective in improving microgreen height, stem diameter and individual microgreen fresh weight. The control treatment generally showed the lowest performance for growth, yield and biochemical traits. Principal component analysis indicated that the first two components explained 94.68% of the total variation among treatments. Correlation analysis showed positive relationships among yield, chlorophyll content, phenolic content and antioxidant capacity. The findings suggest that garlic, willow and wheat extracts can improve specific growth and quality attributes of stinging nettle microgreens under controlled production conditions.