Changes in Nitrate Content and Activities of Nitrate Reductase and Glutamine Synthetase in Hydroponically Grown Leaf Lettuce and Water Dropwort as Influenced by Daylenght, Shading, and Season
1998
Lee, Eung-Ho | Kim, Ki-Deog NHRI, RDA, Suwon 440-310 (Korea Republic)
This study was carred out to investigate the effect of season, plant part, and shading on nitrate content, nitrate reductase, and glutamine synthetase activity of leaf lettuce (Lactuca sativa L.) and water dropwort (Oenanthe stolonifera DC.) grown with hydroponics. Nirate content of the both crops in each plant parts was high in order of stem, petiole and leaf blade. Nitrate content by season was the highest in winter, followed by in autumn, spring and summer. There was no difference in fresh weight of leaf lettrce among no shading, 25%, and 50% shading. Nirate content of the both crops was higher by 14% and 27% under 75% shading, respectively, than those of no shading. The fresh weight of the both crops was higher under 16-hour-daylength condition. Nirate content of the both crops was lower by 26% and 14% at 16-hour-daylength condition than those of 8-hour-daylength condition. The activity of nitrate reductase in the both crops was higher by two times at 16-hour-daylength condition than those of 8-hour-daylength condition. The activity of glutamine synthetase of the both crops was slightly higher than those of nitrate reductase, but the changing trend was similar to nitrate reductase.
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