Abstract
The effects of light intensity and altered red (R)/far-red (FR) photon flux ratio on nitrate concentration and nitrate reductase (NR) activity in komatsuna (Brassica campestris L. cv. ‘Harumi komatsuna’ and ‘Rakuten’) were investigated. Komatsuna was hydroponically grown in full or half strength nutrient solution under different light intensities (PPFD of 165, 290, 350 and 510 μmol · m-2 · s-1) and different R/FR ratios (1.01: control, 0.66: R-intercepted and 1.50: FR-intercepted) conditions. When komatsuna was grown under different light intensities, the nitrate concentration in ‘Harumi komatsuna’ was decreased with increases in light intensity, and the actual NR activity was increased with increase in light intensity. In ‘Rakuten’, the nitrate concentration was decreased and the actual NR activity was increased by increased light intensity at half strength nutrient solution. At full strength nutrient solution, the nitrate concentration was hardly decreased and the actual NR activity did not change with increase in light intensity. When komatsuna was grown under different R/FR ratio conditions, reduction of nitrate concentration was observed only in R-interceptive-treated komatsuna grown with half strength nutrient solution.
