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1844. Combined effect of irradiance and water regime on sorghum photosynthesis

Creator:
Xu, Qingzhang and Kirkham, M. B.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
crop breeding programs, drought resistance, photosynthetic photon flux density (PPFD), Sorghum bicolor, and stomatal resistance
Language:
Multiple languages
Description:
Grain sorghum [Sorghum bicolor (L.) Moench. cvs. TX430 and KS82] was grown in a Haynie very fine sandy loam (coarse-silty, mixed, superactive, calcareous, mesic Mollic Udifluvents) under constant 47 % shade or full irradiance in a greenhouse under two watering regimes to see the combined and individual effects of low irradiance (LI) and low water (LW) on the sorghum genotypes. Under the high-irradiance (HI) and high-water (HW) treatment (control) and the LI-HW treatment, TX430 grew taller than KS82. Both LI and LW reduced several times the fresh and dry masses. Under the control conditions, TX430 reached its maximum net photosynthetic rate (PNmax) of 28.93 μmol m-2 s-1 at a photosynthetic photon flux density (PPFD) of 1 707 μmol m-2 s-1, and KS82 reached its PNmax of 28.32 μmol m-2 s-1 at a PPFD of 2 973 μmol m-2 s-1. The fact that TX430 had PNmax under a lower PPFD than KS82 may relate to its taller growth under LI conditions. Hence genotypes of sorghum might be selected for low irradiance using curves relating PN to PPFD. and Qingzhang Xu, M. B. Kirkham.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1845. Combined effects of cadmium and ozone on photosynthesis of Lycopersicon esculentum

Creator:
Degl’Innocenti, E., Castagna, A., Ranieri, A., and Guidi, L.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, ozon, rajčata, kadmium, photosynthesis, ozone, tomatoes, cadmium, chlorophyll a fluorescence, de-epoxidation index, electron transport rate, gas exchange, xanthophyll cycle, Lycopersicon esculentum, 2, and 581
Language:
Multiple languages
Description:
Tomato (Lycopersicon esculentum Mill. cv. Pearson) plants were grown in growth chambers for 25 days with cadmium (Cd) and then exposed briefly to ozone (O3). Gas exchange, chlorophyll a fluorescence, and pigment composition were analysed in leaves at the end of the treatment to assess the effects of a single pollutant and their combination on photosynthesis. The CO2 assimilation rate was dramatically reduced in plants subjected to the combined treatment, while the single effect of Cd appeared less severe than that of O3. The decline of CO2 photoassimilation found in all O3-exposed plants was attributed to both stomatal and nonstomatal limitations. Tomato plants seemed to detoxify Cd to a great extent, but this resulted in growth suppression. In response to O3 exposure, the plants protected their photosystems by heat dissipation of excess energy via the xanthophyll cycle. Cd combined with O3 affected adversely this cycle resulting in an increase in photosynthetic performance under the same experimental light conditions., E. Degl’Innocenti, A. Castagna, A. Ranieri, L. Guidi., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1846. Combined effects of elevated CO2 concentration and drought stress on photosynthetic performance and leaf structure of cucumber (Cucumis sativus L.) seedlings

Creator:
Liu, B. B., Li, M., Li, Q. M., Cui, Q. Q., Zhang, W. D., Ai, X. Z., and Bi, H. G.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
abiotické faktory, chloroplasty, elektronová mikroskopie, abiotic factors, chloroplasts, electron microscopy, mezofyl, akumulace škrobu, stomata, mesophyll, starch accumulation, 2, and 581
Language:
Multiple languages
Description:
Drought stress is one of the main environmental factors limiting plant growth and productivity of many crops. Elevated carbon dioxide concentration (eCO2) can ameliorate, mitigate, or compensate for the negative impact of drought on plant growth and enable plants to remain turgid and functional for a longer period. In order to investigate the combined effects of eCO2 and drought stress on photosynthetic performance and leaf structures, we analyzed photosynthetic characteristics and structure and ultrastructure of cucumber leaves. The decline in net photosynthetic rate under moderate drought stress occurred due to stomatal limitation alone, while under severe drought stress, it was the result of stomatal and nonstomatal limitations. Conversely, eCO2 improved photosynthetic performance under moderate drought stress, increased the lengths of the palisade cells and the number of chloroplasts per palisade cell under severe drought stress, and significantly increased the grana thickness under moderate drought stress. Additionally, eCO2 significantly decreased stomatal density, stomatal widths and stomatal aperture on the abaxial surface of leaves under moderate drought stress. In conclusion, eCO2 can alleviate the negative effects of drought stress by improving the drought resistance of cucumber seedlings through stomatal modifications and leaf structure., B. B. Liu, M. Li, Q. M. Li, Q. Q. Cui, W. D. Zhang, X. Z. Ai, H. G. Bi., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1847. Combined effects of elevated UV-B radiation and the addition of selenium on common (Fagopyrum esculentum Moench) and tartary [Fagopyrum tataricum (L.) Gaertn.] buckwheat

Creator:
Breznik, B., Germ, M., Gaberščik, A., and Kreft, I.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
biomass, chlorophyll, energy conversion, leaf area and thickness, plant height, and UV-A
Language:
Multiple languages
Description:
The combined effects of UV-B irradiation and foliar treatment with selenium on two buckwheat species, common (Fagopyrum esculentum Moench) and tartary [Fagopyrum tataricum (L.) Gaertn.] buckwheat, that underwent different intensity of breeding, were examined. Plants grown outdoors under three levels of UV-B radiation were studied for 9 weeks, from sowing to ripening. At week 7 they were sprayed with solution containing 1 g(Se) m-3 that presumably mitigates UV-B stress. Morphological, physiological, and biochemical parameters of the plants were monitored. Elevated UV-B radiation, corresponding to a 17 % reduction of the ozone layer, induced synthesis of UV absorbing compounds. In both buckwheat species it also caused a reduction in amounts of chlorophyll a during the time of intensive growth, an effect, which was increased in tartary buckwheat in the presence of selenium. The respiratory potential, measured as terminal electron transport system activity, was lower in plants subjected to enhanced UV-B radiation during the time of intensive growth. The effective quantum yield of photosystem 2 was also reduced due to UV-B radiation in both buckwheat species and was mitigated by the addition of Se. Se treatment also mitigated the stunting effect of UV-B radiation and the lowering of biomass in common buckwheat. and B. Breznik ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1848. Combined effects of irradiance and first autumn frost on CO2 assimilation and selected parameters of chlorophyll a fluorescence in Norway spruce shoots

Creator:
Kalina, J., Marek, M.V., and Špunda, V.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
The state of some parameters of photosynthetic activity in Norway spruce (Picea abies [L.] Karst.) seedlings during the first autumn temperature transition to frost was monitored in October 1991. The trees were grown under field conditions of the Beskydy Mts. (North Moravia, The Czech Republic). Simultaneous measurements of Chi a fluorescence and C02 gas exchange revealed two phases in the functional transition of the assimilatory apparatus. Immediately upon the temperature transition to frost a distinct decrease in the radiant energy saturated rate of C02 uptake was observed and radiationless dissipation was indicated by higher values of the nonphotochemical quenching coefficient. The second period of the transition, a period with prolonged influence of frost together with a higher level of irradiance, was connected with a decrease of photosynthetic efficiency. The overwhelming capacity for protective non-photochemical energy dissipation and the complete reduction of acceptor QA occurred especially at medium and high incident irradiance documenting photoinhibitory damage to the photosynthetic apparatus.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1849. Combined effects of light and temperature on growth, photosynthesis, and pigment content in the mat-forming cyanobacterium Geitlerinema amphibium

Creator:
Jodłowska, S. and Latała, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, Geitlerinema amphibium, irradiance, microbial mats, photosynthesis, pigments, temperature, 2, and 58
Language:
Multiple languages
Description:
Geitlerinema amphibium (BA-13), mat-forming cyanobacterium from the southern Baltic Sea, was grown at three irradiances [5, 65, and 125 μmol(photon) m-2 s-1] and three temperatures (15, 22.5, and 30°C). To determine the effect of the investigated factors and their interaction on culture concentration, pigment content, and photosynthetic parameters of cyanobacterium, factorial experiments and two-way analysis of variance (ANOVA) were carried out. Both chlorophyll (Chl) a and phycobilins (PB) were influenced by the irradiance and temperature, but stronger effect was noted in the case of the former one. Chl a and PB concentration per 100 μm of filament dropped above 4-fold with the increasing irradiance. The ratios between individual carotenoids [β-carotene, zeaxanthin, and myxoxanthophyll (Myx)] and Chl a increased significantly with an increase in the irradiance. The greatest fluctuations were observed in the ratio of Myx to Chl a (above 10-fold). Thus, Myx was suggested as the main photoprotective carotenoid in G. amphibium. Based on photosynthetic light response (PI) curves, two mechanisms of photoacclimation in G. amphibium were recognized: a change of photosynthetic units (PSU) number and a change of PSU size. These two mechanisms constituted the base of significant changes in photosynthetic rate and its parameters, such as the compensation point (PC), the initial slope of photosynthetic curve (α), saturation irradiance (EK), maximal photosynthetic rate (Pmax), and dark respiration rate (RD). The greatest changes were observed in PC values (about 15-fold within the range of the factors tested). Studied parameters showed a wide range of changes, which might indicate G. amphibium ability to acclimatize well to irradiance and temperature, and indirectly might explain the successful growth of cyanobacterium in dynamically changing environmental conditions., S. Jodłowska, A. Latała., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1850. Combined stresses of light and chilling on photosynthesis of Fraxinus mandschurica seedlings in northeastern China

Creator:
Li, X. F., Jin, L., Zhu, C. Y., Wen, Y. J., and Wang, Y.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, mírné pásmo, photosynthesis, temperate zone, chlorophyll fluorescence, early-spring chilling, net photosynthetic rate, 2, and 581
Language:
Multiple languages
Description:
The chilling and light stresses were experimentally created to explore photosynthesis of Fraxinus mandshurica seedlings in northeast China. Net photosynthetic rate, stomatal conductance, and transpiration rate decreased significantly with the decline of temperature and light. Significant interaction effects of light and chilling were observed on gas exchange of photosynthesis. The minimal fluorescence yield of the dark-adapted state (F0) increased with increasing light and decreasing temperature. Both high and low light stresses induced the decreases of the maximal quantum yield of PSII photochemistry (Fv/Fm), photochemical quenching coefficient (qP), nonphotochemical quenching (NPQ), and electron transport rate. Decline of Fv/Fm and increased F0 were observed under decreasing temperatures. Decreased NPQ and qP at frost temperature suggest that F. mandschurica failed to dissipate excess light energy. No interactive effects of chilling and light on chlorophyll fluorescence parameters suggests that F. mandschurica seedlings might be adapted to combined stresses of light and chilling., X. F. Li, L. Jin, C. Y. Zhu, Y. J. Wen, Y. Wang., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public