Abstract
To study the effect of the growth temperature on the nitrate concentration and nitrate reductase (NR) activity in komatsuna (Brassica rapa L. var. perviridis), cv. ’Harumi-komatsuna’ and ’Rakuten’ plants were hydroponically grown under growth temperatures of 10/5, 15/10, 20/15, 25/20, 30/25, and 35/30°C, and a 12-hr photoperiod at a PPFD of 300µmol・m−2・s−1. Generally, the nitrate concentration in ’Rakuten’ plants was higher than that in ’Harumi-komatsuna’. As the growth temperature increased, the nitrate concentration increased and NR activity decreased in both cultivars. A negative correlation between NR activity and the nitrate concentration was observed. Under high temperature conditions, the NR activity decreased, and, therefore, the nitrate concentration in komatsuna plants increased.
