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292. 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

293. 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

294. 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

295. Leaf cuticular waxes and physiological parameters in alfalfa leaves as influenced by drought

Creator:
Ni, Y., Guo, Y. J., Han, L., Tang, H., and Conyers, M.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, drought resistance, lucerne, photosynthesis, stomatal conductance, 2, and 58
Language:
Multiple languages
Description:
Drought significantly constrains higher yield of alfalfa (Medicago sativa L.) in arid and semiarid areas all over the world. This study evaluated the responses of leaf cuticular wax constituents to drought treatment and their relations to gas-exchange indexes across six alfalfa cultivars widely grown in China. Water deficit was imposed by withholding water for 12 d during branching stage. Cuticular waxes on alfalfa leaves were dominated by primary alcohols (41.7-54.2%), alkanes (13.2-26.9%) and terpenes (17.5-28.9%), with small amount of aldehydes (1.4-3.4%) and unknown constituents (4.5-18.4%). Compared to total wax contents, the wax constituents were more sensitive to drought treatment. Drought decreased the contents of primary alcohol and increased alkanes in all cultivars. Alkane homologs, C25, C27, and C29, were all negatively correlated with photosynthetic rate, transpiration rate, stomatal conductance, and leaf water potential. Under drought conditions, both stomatal and nonstomatal factors were involved in controlling water loss from alfalfa leaves. No direct relationship was observed between wax contents and drought resistance among alfalfa cultivars. An increase in alkane content might be more important in improving drought tolerance of alfalfa under water deficit, which might be used as an index for selecting and breeding drought resistant cultivars of alfalfa., Y. Ni ... [et al.]., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

296. Leaf development, gas exchange characteristics, and photorespiratory activity in maize seedlings

Creator:
Kutschera, U., Pieruschka, R., and Berry, J. A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, leaf development, maize seedlings, photorespiration, and photosynthesis
Language:
Multiple languages
Description:
Five decades ago, a novel mode of CO2 assimilation that was later described as C4-photosynthesis was discovered on mature leaves of maize (Zea mays L.) plants. Here we show that 3- to 5-day-old developing maize leaves recapitulate the evolutionary advance from the ancient, inefficient C3 mode of photosynthesis to the C4 pathway, a mechanism for overcoming the wasteful process of photorespiration. Chlorophyll fluorescence measurements documented that photorespiration was high in 3-day-old juvenile primary leaves with non-specialized C3-like leaf anatomy and low in 5-day-old organs with the typical "Kranz-anatomy" of C4 leaves. Photosynthetic gas (CO2)-exchange measurements on 5-day-old leaves revealed the characteristic features of C4 photosynthesis, with a CO2 compensation point close to zero and little inhibition of photosynthesis by the normal oxygen concentration in the air. This indicates a very low photorespiratory activity in contrast to control experiments conducted with mature C3 sunflower (Helianthus annuus L.) leaves, which display a high rate of photorespiration. and U. Kutschera ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

297. 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

298. 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

299. Leaf gas exchange of Pachyrhizus ahipa and P. erosus under water and temperature stress

Creator:
Leidi, E. O.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carbon isotope discrimination, photosynthesis, stomatal conductance, transpiration, water-use efficiency, and yambean
Language:
Multiple languages
Description:
Gas exchange, water relations, and leaf traits were studied in the tuberous-root producing legumes ahipa (Pachyrhizus ahipa) and yambean (P. erosus) under different environmental conditions. Differences in leaf traits (hairiness, leaf area, areal leaf mass, stomatal density) and paraheliotropism were found between ahipa and yambean. Under sufficient water supply, the increase in air temperature and decrease in air humidity increased stomatal conductance (gs) and net photosynthetic rate (PN) in yambean but reduced them in ahipa. In a drying soil (14 d after irrigation), inter-specific variation in gas exchange was only observed in the early morning, and yambean showed a greater sensitivity to water restriction than ahipa. High gs at low humidity increased PN of P. erosus but resulted in lower water-use efficiency (WUE). However, long-term WUE, estimated by leaf carbon isotope discrimination, showed little variation between species. Daily-irrigated ahipa and yambean grown in the greenhouse did not show significant differences in gas exchange. However, leaf temperature was significantly greater in yambean than in ahipa while a steepper relationship between E and PN and gs was observed in ahipa.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

300. Leaf gas exchange, phosphorus uptake, growth and yield responses of cotton cultivars to different phosphorus rates

Creator:
Wang, J., Chen, Y., Wang, P., Li, Y. S., Wang, G., Liu, P., and Khan, A.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
enzymatická aktivita, index listové plochy, fotosyntéza, enzymatic activity, leaf area index, photosynthesis, net assimilation rate, photosynthetic pigments, 2, and 581
Language:
Multiple languages
Description:
Growth and physiological responses of cotton (Gossypium hirsutum L.) cultivars with different phosphorus (P) efficiencies under variable P environment are poorly known. Therefore, this study explored effects of normal P [P+, 70 kg(P2O5) ha-1] and without P (P-, 0 kg ha-1) on yield, growth, and physiology of different P-efficient cultivars [low-efficient Xinluzao 13 (L1) and Xinluzao 26 (L2); medium-efficient Xinluzao 10 (M1) and Xinluzao 24 (M2); high-efficient Zhongmiansuo 42 (H1) and Xinluzao19 (H2)]. Cotton growth and yield was higher in H1 and H2 cultivars under P+ compare to P-. Leaf photosynthesis, intercellular CO2 concentration, stomatal conductance, and net assimilation rate increased under P+ and in high-efficient cultivars. Greater Rubisco activity and higher soluble sugar content further promoted P uptake and utilization efficiency which resulted in a higher yield under normal P+ than that at P- treatment. High-P-efficient cultivars have the potential to increase the yield by improving cotton growth and physiological attributes under P+., J. Wang, Y. Chen, P. Wang, Y. S. Li, G. Wang, P. Liu, A. Khan., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public