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Start Over Rights http://creativecommons.org/licenses/by-nc-sa/4.0/ Subject 581

262. Kaolin-based, foliar reflective film protects photosystem II structure and function in grapevine leaves exposed to heat and high solar radiation

Creator:
Dinis, L -T., Ferreira, H., Pinto, G., Bernardo, S., Correia, C. M., and Moutinho-Pereira, J.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, chlorophyll a fluorescence transient, energy flux, Vitis vinifera, 2, and 581
Language:
Multiple languages
Description:
Extreme conditions, such as drought, high temperature, and solar irradiance intensity, are major factors limiting growth and productivity of grapevines. In a field experiment, kaolin particle film application on grapevine leaves was examined during two different summer conditions (in 2012 and 2013) with the aim to evaluate benefits of this practice against stressful conditions hindering photochemical processes. We used chlorophyll a fluorescence to investigate attached leaves. Two months after the application, during the hottest midday, the kaolin-treated plants showed by the JIP test significantly higher quantum yield of PSII photochemistry, flux ratios, maximum trapped excitation flux of PSI, absorption flux, electron transport flux, maximum trapped energy flux per cross section, and performance index than plants under control conditions in the warmer year. On the contrary, the treated plants showed a lower initial slope of relative variable fluorescence and a decrease in the absorption and electron transport per cross section. The JIP test showed higher efficiency of PSII in the plants treated with kaolin mainly in 2013 (higher temperature and drought). Our results supported the hypothesis that the accumulation of active PSII reaction centres was associated with decreased susceptibility to photoinhibition in the kaolin-treated plants and with more efficient photochemical quenching. Grapevines in the Douro Region seems to profit from the kaolin application., L.-T. Dinis, H. Ferreira, G. Pinto, S. Bernardo, C. M. Correia, J. Moutinho-Pereira., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

264. Lanthanum improves salt tolerance of maize seedlings

Creator:
Liu, R. Q., Xu, X. J., Wang, S., and Shan, C. J.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, antioxidant enzyme, lanthanum chloride, salinity, Zea mays, 2, and 581
Language:
Multiple languages
Description:
In this study, the effects of lanthanum were investigated on contents of pigments, chlorophyll (Chl) fluorescence, antioxidative enzymes, and biomass of maize seedlings under salt stress. The results showed that salt stress significantly decreased the contents of Chl and carotenoids, maximum photochemical efficiency of PSII (Fv/Fm), photochemical quenching (qP), and quantum efficiency of PSII photochemistry (ΦPSII), net photosynthetic rate (P N), and biomass. Salt stress increased nonphotochemical quenching (qN), the activities of ascorbate peroxidase, catalase, superoxide dismutase, glutathione peroxidase, and the contents of malondialdehyde and hydrogen peroxide compared with control. Pretreatment with lanthanum prior to salt stress significantly enhanced the contents of Chl and carotenoids, Fv/Fm, qP, qN, ΦPSII, P N, biomass, and activities of the above antioxidant enzymes compared with the salt-stressed plants. Pretreatment with lanthanum also significantly reduced the contents of malondialdehyde and hydrogen peroxide induced by salt stress. Our results suggested that lanthanum can improve salt tolerance of maize seedlings by enhancing the function of photosynthetic apparatus and antioxidant capacity., R. Q. Liu, X. J. Xu, S. Wang, C. J. Shan., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

265. Lead-induced toxicity and interference in chlorophyll fluorescence in Talinum triangulare grown hydroponically

Creator:
Kumar, A. and Prasad, Majeti Narasimha Vara
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
photosynthesis, Indie, India, ceylon spinach, chlorophyll fluorescence, electron transport rate, photosystems, lead, 2, and 581
Language:
Multiple languages
Description:
We investigated the lead (Pb) effect on chlorophyll (Chl) fluorescence and photosynthetic electron transport system in Talinum triangulare (Jacq.) Willd. Plants were exposed to different concentrations of Pb(NO3)2 (i.e. 0, 0.25, 0.5, 0.75, 1.0, and 1.25 mM) for seven days in hydroponic experiments. Pb-treated leaves exhibited a relative decrease in Chl fluorescence induction curve, which resulted in the decrease of maximal fluorescence yield, maximal quantum yield, and effective quantum yield of PSII, while nonphotochemical quenching, quantum yield of regulated and nonregulated energy dissipation of PSII significantly increased during Pb stress. Furthermore, Pb concentrations also caused a decrease in maximal P700 change, photochemical quantum yield, nonphotochemical quantum yield, and ETR of PSI. We suggested that the changes in these parameters were a manifestation of Pb interference in the electron transport chain in both PSII and PSI. The sensitivity of PSII was greater than that of PSI in T. triangulare leaves., A. Kumar, M. N. V. Prasad., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

266. Leaf anatomy and photosynthetic efficiency of Acrostichum danaeifolium after UV radiation

Creator:
Fonini, A. M., Barufi, J. B., Schmidt, É. C., Rodrigues, A. C., and Randi, Á. M.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
chlorofyl, karotenoidy, chlorophyll, carotenoids, mangrovníky, mladé sporofyty, fotosyntetické parametry, anatomie listů, giant leather fern, mangroves, photoresponse, young sporophyte, photosynthetic parameters, Acrostichum danaeifolium, leaf anatomy, photosynthetic efficiency, 2, and 581
Language:
Multiple languages
Description:
This paper reports effects of ultraviolet B (UVB) radiation on leaf anatomy and contents of chlorophyll and carotenoids, as well as photosynthetic parameters, in young sporophytes of Acrostichum danaeifolium Langsd. & Fisch. (Polypodiopsida, Pteridaceae) exposed to UV radiation treatments for 1 h daily for six weeks. The leaves showed large aerenchyma and present chloroplasts in both epidermises. After cultivation under PAR + UVA + UVB, leaves showed curling and malformed stomata on the abaxial face. After the UV treatment, chloroplasts in leaves were arranged against the inner wall of the epidermal cells. Transmission electron microscopy analysis showed some dilated thylakoids and plastoglobuli in chloroplasts and vesicles containing phenolic compounds in the cytoplasm. Differences were not observed between control and UV-treated plants in their contents of chlorophylls, carotenoids, and photosynthetic parameters. A. danaeifolium grown in sunny mangrove environment seems to have mechanisms preventing photosystem damage., A. M. Fonini, J. B. Barufi, É. C. Schmidt, A. C. Rodrigues, Á. M. Randi., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

267. Leaf area estimation in muskmelon by allometry

Creator:
Misle, E., Kahlaoui, B., Hachicha, M., and Alvarado, P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, allometric model, Cucumis melo L., growth analysis, nondestructive methods, 2, and 581
Language:
Multiple languages
Description:
This study developed a method for estimating the leaf area (LA) of muskmelon by using allometry. The best linear measure was evaluated first, testing both a leaf length and width (W). Leaf samples were collected from plants grown in containers of different sizes, leaves of four cultivars, at different develpoment stages, and of different leaf sizes. Two constants of a power equation were determined for relating allometrically a linear leaf measure and LA, in a greenhouse crop. W proved to be a better fit than the leaf length. The maximum attainable W and LA were estimated at Wx = 15.4 cm and LAx = 174.1 cm2. The indicators of fit quality showed that the function was properly related to LA and W as: LA/LAx = Ao × (W/WLx)b; the allometric exponent was b = 1.89, where R 2 = 0.9809 (n = 484), the absolute sum of squares, 0.4584, and the standard deviation of residues, 0.03084, based on relative values calculations (LA/LA x and W/WLx). The relationship was not affected by the cultivar, crop age, leaf size or stress treatment in the seedling stage. The empirical value of allometric constant (A0) was estimated as 0.963. and E. Misle ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

268. Leaf chloroplast ultrastructure and photosynthetic properties of a chlorophyll-deficient mutant of rice

Creator:
Wu, Z. M., Zhang, X., Wang, J. L., and Wan, J. M.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, rýže, photosynthesis, rice, chlorophyll fluorescence, violaxanthin, ultrastructure, 2, and 581
Language:
Multiple languages
Description:
Leaf chloroplast ultrastructure and photosynthetic properties of a natural, yellow-green leaf mutant (ygl1) of rice were characterized. Our results showed that chloroplast development was significantly delayed in the mutant leaves compared with the wild-type rice (WT). As leaves matured, more grana stacks formed concurrently with increasing leaf chlorophyll (Chl) content. Except for the lower intercellular CO2 concentration, the ygl1 plants had a higher leaf net photosynthetic rate, stomatal conductance, and transpiration rate than those of the WT plants. Under equal amounts of Chl, the excitation energy of PSI and PSII was much stronger in the mutant than that in the WT. The ygl1 plants showed higher nonphotochemical quenching and lower photochemical quenching. They also exhibited higher actual photochemical efficiency of PSII with a higher electron transport rate. Under the light of 200 μmol(photon) m-2 s-1, the ygl1 mutant showed lesser deepoxidation of violaxanthin in the xanthophyll cycle than WT, but it increased substantially under strong light conditions. In conclusion, the photosynthetic machinery of the ygl1 remained stable during leaf development. The plants were less sensitive to photoinhibition compared with WT due to the active xanthophyll cycle. The ygl1 plants were efficient in both light harvesting and conversion of solar energy., Z. M. Wu, X. Zhang, J. L. Wang, J. M. Wan., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

269. Leaf gas exchange and grain yield of common bean exposed to spermidine under water stress

Creator:
Torabian, S., Shakiba, M. R., Dabbagh Mohammadi Nasab, A., and Toorchi, M.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, harvest index, number of pods, water deficit, 2, and 581
Language:
Multiple languages
Description:
Three prevalent aliphatic polyamines (PAs) include putrescine, spermidine, and spermine; they are low-molecular-mass polycations involved in many physiological processes in plants, especially, under stressful conditions. In this experiment, three bean (Phaseolus vulgaris L.) genotypes were subjected to well-watered conditions and two moderate and severe water-stressed conditions with and without spermidine foliar application. Water stress reduced leaf relative water content (RWC), chlorophyll contents, stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate, maximal quantum yield of PSII (Fv/Fm), net photosynthetic rate (PN), and finally grain yield of bean plants. However, spermidine application elevated RWC, gs, Ci, Fv/Fm, and PN, which caused an increase in the grain yield and harvest index of bean plants under water stress. Overall, exogenous spermidine could be utilized to alleviate water stress through protection of photosynthetic pigments, increase of proline and carotenoid contents, and reduction of malondialdehyde content., S. Torabian, M. R. Shakiba, A. Dabbagh Mohammadi Nasab, M. Toorchi., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

270. Leaf gas exchange in species of the Theobroma genus

Creator:
Almeida, A.-A. F., Gomes, F. P., Araujo, R. P., Santos, R. C., and Valle, R. R.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, Bahía (Brazílie), Bahía (Brazil), light-response curves, stomatal conductance, transpiration, water-use efficiency, 2, and 581
Language:
Multiple languages
Description:
Species of the Theobroma genus are primarily known by their commercially valuable seeds, especially, T. cacao is one of the most important tropical perennial crops. Beside T. grandiflorum, T. bicolor, and T. angustifolium, T. cacao is the only species of the genus that has been better studied to obtain physiologically relevant information. The main objective of this work was to evaluate the leaf gas exchange in seedlings of seven species of the Theobroma genus, seeking to identify characteristics that could be used in T. cacao breeding programmes. The study was realized under greenhouse conditions using six-month-old seedlings, in which net photosynthetic rate (PN), stomatal conductance (gs), transpiration (E), as well as parameters derived from light curves (PN vs. photosynthetically active radiation) were evaluated. T. cacao, along with T. microcarpum, showed the lowest values of PN, gs, and E, while the highest values were presented by T. speciosum, which showed higher saturation irradiance and lower intrinsic and instantaneous water-use efficiencies, being considered the species less conservative in water use. Therefore, the parameters shown by the different evaluated species could serve to design T. cacao genotypes, through introgression of genes for specific environments such as the cabruca system widespread in southern Bahia, Brazil., A.-A. F. Almeida, F. P. Gomes, R. P. Araujo, R. C. Santos, R. R. Valle., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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