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192. Aluminium toxicity modulates nitrate to ammonia reduction
- Creator:
- Lidon, F. C., Ramalho, J. C., and Barreiro, M. G.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Al toxicity, ammonia, fresh and dry mass, maize, nitrate, nitrate reductase, nitrite, nitrite reductase, photosynthesis, and Zea mays
- Language:
- Multiple languages
- Description:
- Two weeks-old maize (Zea mays cv. XL-72.3) plants were exposed to Al concentrations 0 (Al0), 9 (Al9), 27 (Al27) or 81 (Al81) g m-3 for 20 d in a growth medium with low ionic strength. Thereafter, the Al concentration-dependent interactions on root nitrate uptake, and its subsequent reduction to ammonia in the leaves were investigated. Al concentrations in the roots sharply increased with increasing Al concentrations while root elongation correspondingly decreased. Root fresh and dry masses, acidification capacity, and nitrate and nitrogen contents decreased from Al27 onwards, whereas leaf nitrogen, nitrate, nitrite, and ammonia concentrations decreased starting with Al9. Electrolytic conductance increased by 60 % in root tissues from Al0 to Al81 but it did not increase significantly in the leaves. In Al9, Al27, and Al81 plants a decrease in shoot fresh and dry masses was observed. Al concentrations between 0 and 27 g m-3 increased net photosynthetic rate, stomatal conductance, and the quantum yield of photosynthetic electron transport, whereas the intercellular CO2 concentration was minimum in Al27 plants. In the leaves, nitrate reductase (E.C. 1.6.6.1) activity increased until Al27, and nitrite reductase (E.C. 1.6.6.4) activity until Al81. Hence there may be an Al mediated extracellular and intracellular regulation of root net nitrate uptake. Nitrate accumulation in the roots affects the translocation rates and, therefore, the nitrate concentration in the leaves. The in vivo reducing power generated by the photosynthetic electron flow does not limit nitrate to ammonia reduction, and the increase of maximum nitrate and nitrite reductase activities parallels the decreasing nitrate, nitrite, and ammonia concentrations. and F. C. Lidon, J. C. Ramalho, M. G. Barreiro.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
193. Alvarez-Cobelas, M., Reynolds, C. S., Sanchez-Castillo, P., Kristiansen, J. (ed.): Phytoplankton and trophic gradients
- Creator:
- Zachleder, V.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- hydrobiology
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
194. Ambasht, R. S., Ambasht, N. K. (ed.): Modern trends in applied terrestrial ecology
- Creator:
- Květ, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- ecology
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
195. Ambient levels of UV-B in Hawaii combined with nutrient deficiency decrease photosynthesis in near-isogenic maize lines varying in leaf flavonoids: Flavonoids decrease photoinhibition in plants exposed to UV-B
- Creator:
- Lau, T. S. L., Eno, E., Goldstein, G., Smith, C., and Christopher, D. A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- anthocyanins, chlorophyll fluorescence, CO-assimilation, stomatal conductance, and Zea
- Language:
- Multiple languages
- Description:
- Near-isogenic lines of maize varying in their genes for flavonoid biosynthesis were utilized to examine the effects of foliar flavonoids and nutrient deficiency on maximum net photosynthetic rate (PN) and chlorophyll (Chl) fluorescence (Fv/Fm) in response to ultraviolet-B (UV-B) radiation. Plants with deficient (30 to 70 % lower N, K, Mn, Fe, and Zn) and sufficient nutrients were exposed to four irradiation regimes: (1) no UV-B with solar photosynthetically active radiation (PAR), (2) two day shift to ambient artificial UV-B, 8.2-9.5 kJ m-2 d-1 (21-25 mmol m-2 d-1); (3) continuous ambient artificial UV-B; (4) continuous solar UV-B in Hawaii 12-18 kJ m-2 d-1 (32-47 mmol m-2 d-1). The natural ratio of UVB: PAR (0.25-0.40) was maintained in the UV-B treatments. In the adequately fertilized plants, lines b and lc had higher contents of flavonoids and anthocyanins than did lines hi27 and dta. UV-B induced the accumulation of foliar flavonoids in lines hi27 and b, but not in the low flavonoid line dta or in the high flavonoid line lc. In plants grown on deficient relative to adequate nutrients, flavonoid and anthocyanin contents decreased by 30-40 and 40-50 %, respectively, and Chl a and Chl b contents decreased by 30 and 70 %, respectively. The UV-B treatments did not significantly affect PN and Fv/Fm in plants grown on sufficient nutrients, except in the low flavonoid lines dta and hi27 in which PN and Fv/Fm decreased by ∼15 %. PN, Fv/Fm, and stomatal conductance decreased markedly (20-30 %) in all lines exposed to UV-B when grown on low nutrients. The decrease in Fv/Fm was 10 % less in higher flavonoid lines b and lc. The photosynthetic apparatus of maize readily tolerated ambient UV-B in the tropics when plants were adequately fertilized. In contrast, ambient UV-B combined with nutrient deficiency significantly reduced photosynthesis in this C4 plant. Nutrient deficiency increased the susceptibility of maize to UV-B-induced photoinhibition in part by decreasing the contents of photoprotective compounds. and T. S. L. Lau ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
196. Ameliorating effects of three kinds of antioxidants to ozone-polluted painted nettle (Coleus blumei Benth.)
- Creator:
- Zhang, L., Jia, L. L., Sui, J. X., Wen, M. X., and Chen, Y. J.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fluorescence chlorofylu a, výměna plynu, kinetin, Na-askorbát, spermidin, chlorophyll a fluorescence, gas exchange, Na-ascorbate, spermidine, 2, and 581
- Language:
- Multiple languages
- Description:
- Ground concentration of ozone (O3) causes serious threat to plants. In order to protect sensitive plants from O3 pollution, many kinds of antioxidants were assessed in previous studies. In this study, effects of O3 fumigation (a single spike of 120 ± 20 nmol mol-1 for four hours) on an ornamental species (Coleus blumei) was examined in open-top chambers. Before the O3 treatment, plants were sprayed respectively either with a solution of three different antioxidants [Na-ascorbate (NaAsA), kinetin (KIN), and spermidine (Spd)] or with distilled water to compare their protective effects to plants. Our results revealed that O3 fumigation impaired the plasma membrane, decreased chlorophyll (Chl) content, inhibited photosynthesis, induced photoinhibition and photodamage, and caused visible injury. Spraying with KIN, NaAsA or Spd ameliorated the decrease of the Chl content and photosynthetic capability, the impairment of membrane, and visible injury under O3 fumigation. The plants treated with KIN showed the best ability to mitigate the injury caused by O3., L. Zhang, L. L. Jia, J. X. Sui, M. X. Wen, Y. J. Chen., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
197. Ameliorative role of salicylic acid and spermidine in the presence of excess salt in Lycopersicon esculentum
- Creator:
- Fariduddin, Q., Khan, T. A., Yusuf, M., Aafaqee, S. T., and Khalil, R. R. A. E.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- abiotické faktory, antioxidanty, fotosyntéza, abiotic factors, antioxidants, photosynthesis, prolin, kyselina salicylová, spermidin, rajče jedlé, proline, salicylic acid, spermidine, Lycopersicon esculentum, 2, and 581
- Language:
- Multiple languages
- Description:
- Salicylic acid (SA) and polyamines (PA) are widely used to overcome various abiotic stresses including salt (NaCl) stress in plants. In the present investigation, co-application efficacies of SA and PA on the salt stress (200 mM NaCl) were evaluated in Lycopersicon esculentum. After transplantation, at 10-d stage, seedlings were exposed to NaCl through soil and then allowed to grow till 30-d stage. At 31-d stage of growth, plants were sprayed with double distilled water (control) or spermidine (1.0 mM) and/or SA (10-5 M). The salt stress significantly reduced the growth, gas-exchange parameters, but increased antioxidant enzymes and proline content in the leaves. Moreover, the loss caused by salt stress was successfully restored by the following treatment of spermidine and SA., Q. Fariduddin, T. A. Khan, M. Yusuf, S. T. Aafaqee, R. R. A. E. Khalil., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
198. An evaluation of non-destructive methods to estimate total chlorophyll content
- Creator:
- Cassol, D., de Silva, F. S. P., Falqueto, A. R., and Bacarin, M. A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Ceiba, Cucumis, Raphanus, and Zea
- Language:
- Multiple languages
- Description:
- The portable chlorophyll (Chl) meter (CL-01, Hansatech) has been successfully used for a rapid and direct estimation of total Chl content in the leaves of some crops. We compared CL-01 meter readings (Chl value) and Chl contents in leaves of Zea mays, Cucumis sativus, Raphanus sativus, and Ceiba speciosa. Chl index was linearly and positively correlated to Chl content in all the species. and D. Cassol ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
199. An improved method for the simultaneous determination of photosynthetic O2 evolution and CO2 consumption in Rhizophora mucronata leaves
- Creator:
- Ulqodry, T. Z., Nose, A., and Zheng, S.-H.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, carbon dioxide consumption, oxygen evolution, photosynthetic performance, 2, and 581
- Language:
- Multiple languages
- Description:
- The photosynthetic gas-exchange has been assessed traditionally either as O2 evolution or CO2 consumption. In this study, we used a liquid-phase O2 electrode combined with CO2 optodes to examine simultaneously photosynthesis in intact leaves of mangrove Rhizophora mucronata. We verified suitable conditions for leaf photosynthetic rates by assessing pH levels and NaHCO3 concentrations and compared these to the gas-exchange method at various PAR levels. The photosynthetic rate in response to pH exhibited a similar pattern both for O2 evolution and CO2 consumption, and higher rates were associated with intermediate pH compared with low and high pH values. The net photosynthetic quotient (PQ) of R. mucronata leaves ranged from 1.04-1.28. The PQ values, which were never lesser than 1, suggested that photorespiration did not occur in R. mucronata leaves under aqueous conditions. The similar maximum photosynthetic rates suggested that all measurements had a high capacity to adjust the photosynthetic apparatus under a light saturation condition. The simultaneous measurements of O2 evolution and CO2 consumption using the Clark oxygen electrode polarographic sensor with the CO2 optode sensor provided a simple, stable, and precise measurement of PQ under aqueous and saturated light conditions., T. Z. Ulqodry, A. Nose, S.-H. Zheng., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
200. An open Internet of Things (IoT)-based framework for feedback control of photosynthetic activities
- Creator:
- Yuan, S., Tang, H., Fu, L. J., Tan, J. L., Govindjee, G., and Guo, Y.
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, greenhouse, Internet of things, open framework, photosynthesis model, and plant growth chamber
- Language:
- Multiple languages
- Description:
- Active control of photosynthetic activities is important in plant physiological study. Although models of plant photosynthesis have been built at different scales, they have not been fully examined for their application in plant growth control. However, we do not have an infrastructure to support such experiments since current plant growth chambers usually use fixed control protocols. In our current paper, an open IoT-based framework is proposed. This framework allows a plant scientist or agricultural engineer, through an application programming interface (API), in a desirable programming language, (1) to gather environmental data and plant physiological responses; (2) to program and execute control algorithms based on their models, and then (3) to implement real-time commands to control environmental factors. A plant growth chamber was developed to demonstrate the concept of the proposed open framework.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public