抄録
It has been proposed that cold acclimatization of the plant body enhances the nutritional value of leaf vegetables; however, little is known about the optimal duration of cooling required to enhance the quality of factory-processed vegetables. The ideal low temperature acclimatization period increases ascorbic acid and sugar content without increasing the nitrate ion concentration for a given root area. Here, we investigated the ascorbic acid and sugar contents in spinach with a given root area subject to chilling for different durations; 2, 4, 5, 6, and 7 days. Ascorbic acid and sugar content levels remained stable at the beginning of chilling; however, after 6 days, the levels of both parameters doubled compared to those in the control (no chilling). In comparison, nitrate ion concentration gradually decreased with increasing acclimatization period. Spinach plants acclimatized for 7 days showed similar results as those acclimatized for 6 days. Our results show that the optimal duration for root area chilling to produce high quality spinach is 6 days, when controlling the temperature of the nutrient solution under plant factory conditions.
