• Horticultural Science & Technology
• /
• v.31 no.4
• /
• pp.393-399
• /
• 2013

The effect of solution temperature and nitrogen form on cucumber (Cucumis sativus L.) growth, photosynthesis and nitrogen metabolism was investigated in hydroponic culture. Cucumber plants were grown for 35 days in a greenhouse at three constant solution temperatures ($15^{\circ}C$, $20^{\circ}C$, and $25^{\circ}C$) within a natural aerial temperature ($15-30^{\circ}C$). Four nitrate:ammonium ($NO{_3}^-:NH{_4}^+$) ratios (10:0, 8:2, 5:5, and 2:8 $mmol{\cdot}L^{-1}$) at constant nitrogen (N) concentration of $10mmol{\cdot}L^{-1}$ were applied within each solution temperature treatment. Results showed an increasing solution temperature enhanced plant growth (height, dry weight, and leaf area) in most N treatments. Dry weight accumulation was greatest at the 10:0 $NO{_3}^-:NH{_4}^+$ ratio in the $15^{\circ}C$ solution, the 5:5 ratio in the $20^{\circ}C$ solution and the 8:2 ratio in the $25^{\circ}C$ solution. Photosynthetic rate (Pn) response to solution temperature and $NO{_3}^-:NH{_4}^+$ ratio was similar to that of plant growth. Probably, the photosynthate shortage played a role in the reduced biomass formation. Increasing solution temperature enhanced the nitrate reductase (NR) activity, and further reduced shoots nitrate content. Our results indicate that the optimal ratio of nitrate to ammonium that promotes growth in hydroponic cucumber varies with solution temperature.

• Journal of Bio-Environment Control
• /
• v.15 no.1
• /
• pp.84-90
• /
• 2006

This study was conducted to anticipate nitrate reduction state in tree through measurement of nitrate reductase activity (NRA) and investigate the effect of nitrogen concentrations (100, 200, 400, and 600 $mg\;L^{-1}$) on growth, the nitrogen content of various tissue, and NRA of pear (Pyrus pyrifolia cv. Niitaka) seedlings in sand culture. Nutrient solutions used in this experiment were adjusted to pH 6.5 and fixed the ratio of ammonium and nitrate to 1:3 and trickle-irrigated 3 times a day. Tree height and dry weight of various organs in seedlings were higher in low nitrogen concentration (100 and 200 $mg\;L^{-1}$) than in high nitrogen concentration (400 and 600 $mg\;L^{-1}$). The shoot growth in 600 $mg\;L^{-1}$ was extremely poor by nitrogen over supply. Increasing the nitrogen concentration, the concentration of nitrate-N in leaves and roots were insignificantly changed but that of stems increased. The accumulation of total and reduced nitrogen in all organs with increasing concentrations of nitrogen supply were increased at 30 days after treatment but those of all organs at 60 and 90 days after treatment were highest in 600 $mg\;L^{-1}$, whereas there were no significant changes among other nitrogen concentration. The in vivo (${+NO_3}^-$) NRA of all organs did not relate to nitrogen concentration but the in vivo (${-NO_3}^-$) NRA of leaves except roots increased with increasing the nitrogen concentration. Therefore, the proper nitrogen concentration to promote growth and nitrate reduction of pear tree was 200 $mg\;L^{-1}$.

• KSBB Journal
• /
• v.5 no.2
• /
• pp.151-158
• /
• 1990

Investigations on the liability of nitrogen usuage by Nostoc muscorum that has nitrogen fixing ability, and cultured tobacco cells as they were associately cultured on nitrogen-free media and effects of polyamine on the associated culture condition were carried out. In addition, measurement on the activity of nitrate reductase, glutamine synthetase, glutamate dehydrogenase and glutamate synthase that take part in the metabolic pathway of nitrogen fixation product were performed. Among enzymes participating in the metabolic pathway of nitrogen fixation products, the activity of nitrogen reductase stimulated five times in associated culture, and that of glutamine synthetase of N. muscorum increased two times after heterocyst differentiated. Activity of glutamate dehydrogenase increased markedly when cultured tobacco cells were solely incubated on nitrogen-free media, but inhibited when cultured associately. And, glutamate synthase was showed the highest activity in 0.1 mM of spermine treated group.

• The Korean Journal of Ecology
• /
• v.9 no.1
• /
• pp.1-7
• /
• 1986

plastochron index was used as a measure for the nitrate reductase activity (NRA) in Amaranthus retroflexus, Chenopodium album var. centrorubrum and Glycine max. The material plants treated with $NO_3$-N had higher NRA than those treated with ${NH_4}^+$-N. High NRA were found in young tissues which have low PI or LPI in both A. retroflexus and C. album. These results indicated that this enzyme decreased with increasing plastochron index of the extracted tissues. High level of NRA was detected in Glycine max leaves at PI 4.0. On the other hand, there were no significant differences for PI among $NO_3$-treated, ${NH_4}^+$-treated and control in both stems and roots.

• Journal of the Korean Society of Tobacco Science
• /
• v.4 no.1
• /
• pp.1-5
• /
• 1982

The metabolic enzymes, nitrate reductase, amylase and peroxidase and the Photorespiratory enzyme, Slycolate oxidise in Nicotiana tabacum varieties were studied at various growth stages. The enzyme activities of young leaves with rapid growth were different from those of old ones with stationary growth. In young leaves, activity of nitrate reductase was higher than that in mature ones and amylase activity was fairly constant in all stages. Activities of glycolate oxidise and peroxidase were found to be significantly lower in young leaves than in mature ones. Activity of glycolate oxidase in mature middle leaves was 2.45 times higher than that of young ones and inhibited by 36% when the enzyme was treated with 0.16 mM isonicotinic hydrazide.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.7
• /
• pp.752-756
• /
• 2006

The independent anoxic reactor was introduced in biological aerated filters as the regulation of water quality requirement, especially total nitrogen, had been strengthened. The process studied in this work was upflow $Biobead^{(R)}$ process which was used commercial invented for removal of organic materials and nitrification. For the purpose of evaluating the independent anoxic reactor, PCR-DGGE, of the molecular biological methods, was performed. Two types of nitrite reductase genes were selected. One is nirS represented cytocrome $cd_1$ nitrite reductase gene and the other is nirK represented Cu-containing nitrite reductase gene. Denitrifier community in the independent anoxic reactor was analyzed with PCR-DGGE using these two denitrifying functional genes. As the result of the PCR, only nirS gene was detected between nirS and nirK. With the result of the DGGE, specific bands became strong, as the operating days were longer, nitrate loading rate was increased. otherwise those of the initial activated sludge showed various bands. In the consequence of the sequence of DGGE bands, various denitrifiers were sequenced in the initial activated sludge, while specific denitrifiers like alcaligenes faecalis were predominant in the anoxic reactor. Consequently, introduction of the independent anoxic reactor made it possible to achieve 96% denitrification efficiency, and was proper for the modification of BAF process.

• BMB Reports
• /
• v.45 no.6
• /
• pp.342-347
• /
• 2012

Plant mitochondria possess alternative respiratory pathways mediated by the type II NAD(P)H dehydrogenases and alternative oxidases. Here, E3 SUMO ligase was shown to regulate alternative respiratory pathways and to participate in the maintenance of carbon and nitrogen balance in Arabidopsis. The transcript abundance of the type II NAD(P)H dehydrogenases NDA2 and NDB2 and alternative oxidases AOX1a and AOX1d genes was low in siz1-2 mutants compared to that in wild-type. The addition of nitrate or ammonium resulted in a decrease or an increase in the expression of the same gene families, respectively, in both wild-type and siz1-2 mutants. The amount of free sugar (glucose, fructose and sucrose) was lower in siz1-2 mutants than that in wild-type. These results indicate that low nitrate reductase activity due to the AtSIZ1 mutation is correlated with an overall decrease in alternative respiration and with a low carbohydrate content to maintain the carbon to nitrogen ratio in siz1-2 mutants.

• Journal of Plant Biology
• /
• v.34 no.4
• /
• pp.253-260
• /
• 1991

Spirodela polyrhiza and Lemna aequinoctialis often occurred at the sites of high ammonium concentration and at the sites of high nitrate concentration, respectively. We investigated the different distribution between two species in relation to the type of nitrogen sources and their concentrations. Our experiments showed that L. aequinoctialis grew faster than S. polyrhiza in nitrate media with lower than 15 mM concentration. The nitrate uptake was also faster in L. aequinoctialis than in S. polyrhiza. However, neither differences in growth nor in uptake patterns between these two species were observed in ammonium media. Glutamine synthetase (GS), glutamate dehydrogenase (GDH) and glutamate synthetase (GOGAT) activities were higher in L. aequinoctialis. In particular, nitrate reductase activity (NRA) in L. aequinoctialis was 12.1 times as high as that in S. polyrhiza. These results showed that the two species responded varyingly to the types of nitrogen sources and their concentrations. Therefore, the difference in geographic distribution between the two species appeared to reflect the interspecific differences in enzyme activities and, subsequently, nitrogen absorption abilities.

• Journal of Life Science
• /
• v.32 no.8
• /
• pp.659-665
• /
• 2022

Chlorella vulgaris is an important freshwater alga that is widely used as a food source by humans and animals. Recently, Chlorella has received considerable attention with regard to its potential application in aquaculture and the production of biofuels, nutrients, and therapeutic proteins. Recently, our laboratory acquired a new strain of C. vulgaris, PKVL7422, characterized by fast growth, ease of culture, and cultivability under dark conditions. However, the genes involved in its nitrogen assimilation are unknown. In this work, we identified the nitrate reductase (NR) gene of C. vulgaris PKVL7422 using rapid amplification of cDNA ends and genome walking. The NR gene of C. vulgaris PKVL7422 is approximately 8 kb long and composed of 18 introns and 19 exons, which encode 877 amino acids. An alignment analysis of the NR gene showed that it possesses the five domains and several invariant residues found in plant NRs. These results provide new insight into the molecular organization of the NR gene in algae.

• Korean Journal of Soil Science and Fertilizer
• /
• v.20 no.1
• /
• pp.43-53
• /
• 1987

In order to improve effectiveness of rhizobia- legume symbiotic nitrogen fixation, ecological and physiological characteristics of indigenous rhizobia distributed in Korea, that is, symbiotic effectiveness of indigenous soybean rhizobia, nitrate reductase activities of the soybean bacteroid from five different soils, and differences of host-infection abilities among the soybean cultivars under population densities of the same indigenous soybean rhizobia, were investigated. The results were summarized as follows: 1. The number of indigenous soybean rhizobia was ranged from $9.2{\times}10^2$ cells per gram of soil in calcareous soil II to $42.4{\times}10^3$ cells per gram of soil in calcareous soil I in Danyang. 2. The symbiotic effectiveness of indigenous soybean rhizobia from five different soils was high in the case of soybean continuously cultivated, and calcareous soil I that population densities of indigenous soybean rhizobia were observed highly. 3. Inverse relationship was observed between total nitrogenase activity (TNA) and nitrate reductase activity (NRA) from the soybean bacteroids ($r=-0.502^*$), but the correlation between nitrate reductase and specific nitrogenase activities (SNA) could be devided into two groups. It was classified into group I which is high in SNA and low in NRA, and group II which is low in SNA and high in NRA. 4. The infection ability of the indigenous soybean rhizobia in the same soil conditions showed the reciprocal difference among each soybean cultivars. In Kwangkyo and Jangyeup, the symbiotic effectiveness appeared by infection of indigenous soybean rhizobia was higher than it of the other soybean cultivars.