Bioactive Content of Salvia plebeia R. Br. Enhanced by Pre-Harvest Exposure to Low Temperatures in a Closed-type Plant Production System

Abstract

The study aim here is to discover a short-term low-temperature method before harvest that can increase the bioactive content of Salvia plebeia R. Br. grown in a closed-type plant production system (CPPS) while maintaining the marketable quality of this herb. Salvia plebeia R. Br. was cultivated for 36 d in a CPPS with a deep floating technique and a recycling system. Low- temperature treatments (15°C) were applied for 1, 3, 5, 10, and 15 days prior to harvest (D1, D3, D5, D10, and D15). The fresh weights of the roots did not differ significantly among the low-temperature treatments. However, the leaf length, leaf width, leaf shape index and fresh and dry weights of the shoots decreased in D5, D10, and D15. The chlorophyll fluorescence decreased for up to three days of the low-temperature treatment and then increased after five days at the low temperature. The total phenolic and flavonoid contents were highest in D3. The findings here suggest that in order to increase the content of bioactive compounds without decreasing the growth of Salvia plebeia R. Br, exposing the plants to low temperatures three days before harvest is a viable strategy.