Effect of light intensity and temperature on the growth and functional compounds in the baby leaf vegetable plant peucedanum japonicum thunb

Abstract

This study was carried out to determine the optimal light intensity and temperature for cultivation of Peucedanum japonicum Thunb., a new baby leaf vegetable, and to improve the functional compounds through short-term stress just before harvesting. Plants were cultivated in a controlled environment at a temperature of 25 ± 1°C and relative humidity of 60 ± 5% for 16 days. Plants 3-5 cm high with 1st and 2nd true leaves were grown with different light intensities or temperatures. Treatments were 50, 100, 250, or 500 µmol·m-2·s-1 PPFD and 18/14°C, 24/20°C and 30/26°C of day and night temperature. At the harvest time of the baby leaf vegetables, growth, chlorophyll content, and functional compounds were investigated. The optimum light intensity for growth of P. japonicum Thunb. was PPFD 250 for 12 days, and the best temperature was 24/20°C. Total phenolic content was higher under high light intensity and low temperature treatment. When the plants were treated for 3 days with temperature (18/14°C and 25/20°C) and light intensity (PPFD 200 and 500) before harvesting, there was no difference in growth, but total phenolic content was high in PPFD 200 or 500 under 18/14°C treatments. Free radical activity (DPPH) was significant for temperature and light treatment. The highest free radical activity was in PPFD 500 under 18/14°C treatments. Therefore, after cultivation at optimal light and temperature, low-temperature treatment for three days before harvesting was effective for enhancing the functional contents.