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Park Y.H.,Korea Greenhouse Crop Research Institute | Seo B.S.,Korea Greenhouse Crop Research Institute
Horticulture Environment and Biotechnology | Year: 2012

In this study, addition of ascorbic acid (AsA) to a reconstituted system composed of nitrite reductase (NiR) and ferredoxin (Fd) proteins could reduce nitrite at a rate nearly equal to that is obtainable with the NADPH-FNRFd-NiR system. The addition of spinach (Spinacia oleracea L. 'Birohurei') leaf extract (LES) enabled acceleration of nitrite reduction in the former system but not in the latter system. In the AsA-Fd-NiR-LES system, switching the incubation atmosphere from air to N2 gas also accelerated nitrite reduction. We added 15N-labeled nitrite to the system and examined the formation of ammonia by using a 15N-tracing technique. At pH 6.5, we observed quantitative recovery of 15N-labeled ammonia in reference with nitrite reduction, but ammonia loss was apparent in the assay at pH 7.5. © 2012 Korean Society for Horticultural Science.


Park Y.H.,Korea Greenhouse Crop Research Institute | Seo B.S.,Korea Greenhouse Crop Research Institute
Horticulture Environment and Biotechnology | Year: 2011

For verification that ascorbic acid can affect on the process of nitrite reduction, reduced form of ascorbic acid (AsA) dissolved in the pH 7.5 buffer solution was added and vacuum-infiltrated into spinach (Spinacia oleracea L.) leaf sections. The endogenous nitrite was reduced in accordance with AsA oxidation by the higher rate with addition of AsA than that without it. In addition, when 15N-labelled nitrite was added to the leaf sections together with AsA, higher 15N contents were found in ammonia and the reduced soluble form of N (ammonia and amino acids) within short periods in the leaf sections treated with AsA than without it. The crude enzymes in the leaf extract from spinach leaves could reduce nitrate to nitrite in the presence of AsA but the rate was less than that in the presence of NADH. Formation of nitric oxide from nitrite by nitrate reductase in leaf extract in the presence of AsA (at pH 7. 5) was estimated to be insignificant. Addition of AsA and (Fd) ferredoxin to the leaf extract could reduce nitrite at higher rate than that of NADPH(Nicotinamide Adenine Dinucleotide Phospate)-FNR(Ferredoxin NADP+ Reductase) -Fd system. These results suggest the possible electron donation from AsA to nitrite reduction via Fd in the dark. © 2011 Korean Society for Horticultural Science.


Park Y.H.,Korea Greenhouse Crop Research Institute | Ryu H.Y.,Korea Greenhouse Crop Research Institute | Choo H.M.,Korea Greenhouse Crop Research Institute | Kim M.H.,Korea Greenhouse Crop Research Institute | Seo B.S.,Korea Greenhouse Crop Research Institute
Acta Horticulturae | Year: 2014

The objective of this study was to quantify the effect of artificial lighting on yield and growth of strawberry. We used three artificial light treatments, including LED, sodium light, fluorescent light as well as a non-treated Control was only natural light. In addition to natural lighting during the day, plants were exposed to three types of artificial lighting during a 2-h period after sunset. A fourth treatment (control) received no supplemental lighting. Accumulated fruit number and fruit weight were determined as a function of light treatment. Plants were divided into root, leaf, stem, and fruit tissues for dry weight analyses. The effect of light regime on plant length, leaf width, leaf length, leaf number, fresh weight, dry weight, leaf area, chlorophyll content and nitrate content were also quantified. We analyzed plant growth using NAR (net assimilation rate), CGR (crop growth rate), and RGR (relative growth rate) plants that received supplemental lighting had greater accumulated fruit weight compared to that of the control treatment. Plants exposed to LED, fluorescent and sodium light sources had greater accumulated fruit weight (44, 18 and 34% greater, respectively) compared to that of the control treatment. While plants exposed to LED, fluorescent and sodium light sources were 23, 33 and 41% taller than that of control plants. © 2014, International Society for Horticultural Science. All rights reserved.

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