Number of results to display per page
Search Results
4222. Resistance of spinach plants to seawater stress is correlated with higher activity of xanthophyll cycle and better maintenance of chlorophyll metabolism
- Creator:
- Sun, J., Jia, X. Y., Guo, S. R., Li, J., and Shu, S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, chlorophyll metabolism, photoinhibition, seawater, spinach, and xanthophyll cycle
- Language:
- Multiple languages
- Description:
- The relationship between the activity of xanthophyll cycle and chlorophyll (Chl) metabolism was investigated using two cultivars, Helan No. 3 (seawater-tolerant cultivar) and Yuanye (seawater-sensitive cultivar), of spinach (Spinacia oleracea L.) plants cultured in Hoagland's nutrient solution, with or without seawater (40%). The results showed that, in plants of two cultivars with seawater, the xanthophyll cycle seems to show a principal protection mechanism against photoinhibition under seawater stress. Furthermore, accumulation of reactive oxygen species (ROS) in chloroplasts of two cultivars was enhanced by seawater to lower the activity of porphobilinogen deaminase. Namely, the conversion of porphobilinogen into uroporphyrinogen III involved in Chl biosynthetic processes was inhibited by seawater. In Helan No. 3 spinach plants with seawater, higher activity of xanthophyll cycle in the leaves dissipated more excess light energy, which appeared to lower the levels of ROS in chloroplasts. As a consequence, the Chl biosynthesis in Helan No. 3 leaves with seawater showed only a weak inhibition and the activity of chlorophyllase (Chlase) was not affected by seawater stress. In contrast, a more pronounced accumulation of ROS in chloroplasts of Yuanye leaves, which possess lower xanthophyll cycle activity, severely inhibited Chl biosynthesis and remarkably enhanced the activity of Chlase, which aggravates the decomposition of Chl. These results suggest that higher activity of xanthophyll cycle in seawater-tolerant spinach plays a role in maintaining Chl metabolic processes, probably by decreasing the levels of ROS, when the plants are cultured in the nutrient solution with seawater (40%). and J. Sun ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4223. Response of bell-pepper (Capsicum annuum L.) photosynthesis, growth, and flower and fniit setting to night temperature
- Creator:
- Bhatt, R. M. and Sriniivasa Rao, N. K
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Net photosynthetic rate growth and flower and firoit settíng pattems were studied in two cultivars of bell-pepper (Ccpsicum annuum L. cv. Arka Mohini, a detenninate type and Arka Basant, an indetenninate type) grown at two different night temperatures. and growdi were higher at high night temperature (27/22 <*C, day/night) dian at low night temperature (27/17 °C) in bodl cultivars. The flower and fitiit numbers were higher in die plants grown at 27/17 °C than at 27/22 oC.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4224. Response of bell-pepper (Capsicum annuum L.) to defoliation. Photosynthesis, dry matter and fruit growth
- Creator:
- Bhatt, R. M. and Srivinasa Rao, N. K.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- The effect of defolíation on net photosynthetic rate (Pn), dry matter production and fruit growth was studied in bell-pepper (Capsicum annuum L. cv. Arka Gaurav). Considerable differences in were observed between defoliated and non-defoliated plants. Defolíation influenced the total dry matter production, leaf area and the relative growth rate of the plants. The bell-pepper has the capacity to compensate photosynthetically for a certain degree of defolíation without reducing the biological yield. No significant differences in the dry matter of fruits per plant were foímd between defoliated and non-defoliated plants.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4225. Response of dominant grassland species in the temperate steppe of Inner Mongolia to different land uses at leaf and ecosystem levels
- Creator:
- Liu, M., Gong, J. R., Pan, Y., Luo, Q. P., Zhai, Z. W., Yang, L. L., and Xu, S.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- osmoregulace, osmoregulation, výměna plynu, efektivita využívání vody, gas exchange, water-use efficiency, 2, and 581
- Language:
- Multiple languages
- Description:
- In order to study the responses of dominant species to different land uses in the semiarid temperate grassland of Inner Mongolia, we tested the physiological responses of Stipa grandis, Leymus chinensis, and Artemisia frigida to mowing, grazing exclusion, and grazing land uses at the leaf and ecosystem levels. The grazing-exclusion and mowing sites released CO2, but the grazing site was a net carbon sink. L. chinensis and S. grandis contributed more to the ecosystem CO2 exchange than A. frigida. At the grazing-exclusion and mowing sites, Leymus chinensis and Stipa grandis both exhibited a higher light-saturation point and higher maximum photosynthetic rate than that at the grazing site, which increased photosynthesis and growth compared to those at the grazing site. In contrast, A. frigida possessed a higher nitrogen content than the other species, and more of the light energy used for photosynthesis, particularly at the grazing site., M. Liu, J. R. Gong, Y. Pan, Q. P. Luo, Z. W. Zhai, L. L. Yang, S. Xu., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4226. Response of effective quantum yield of photosystem 2 to in situ temperature in three alpine plants
- Creator:
- Braun, V. and Neuner, G.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence induction, heat, Loiseleuria procumbens, photoinhibition, Saxifraga paniculata, Soldanella pusilla, and temperature optimum
- Language:
- Multiple languages
- Description:
- The response of effective quantum yield of photosystem 2 (ΔF/Fm') to temperature was investigated under field conditions (1 950 m a.s.l.) in three alpine plant species with contrasting leaf temperature climates. The in situ temperature response did not follow an optimum curve but under saturating irradiances [PPFD >800 µìmol(photon) m-2s-1] highest ΔF/Fm' occurred at leaf temperatures below 10°C. This was comparable to the temperature response of antarctic vascular plants. Leaf temperatures between 0 and 15°C were the most frequently (41 to 56%) experienced by the investigated species. At these temperatures, ΔF/Fm' was highest in all species (data from all irradiation classes included) but the species differed in the temperature at which ΔF/Fm' dropped below 50% (Soldanella pusilla >20°C, Loiseleuria procumbens >25°C, and Saxifraga paniculata >40°C). The in situ response of ΔF/Fm' showed significantly higher ΔF/Fm' values at saturating PPFD for the species growing in full sunlight (S. paniculata and L. procumbens) than for S. pusilla growing under more moderate PPFD. The effect of increasing PPFD on ΔF/Fm', for a given leaf temperature, was most pronounced in S. pusilla. Despite the broad diurnal leaf temperature amplitude of alpine environments, only in S. paniculata did saturating PPFD occur over a broad range of leaf temperatures (43 K). In the other two species it was half of that (around 20 K). This indicates that the setting of environmental scenarios (leaf temperature×PPFD) in laboratory experiments often likely exceeds the actual environmental demand in the field. and V. Braun, G. Neuner.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4227. Response of gas exchange and yield components of field-grown Triticum aestivum L. to elevated ozone in China
- Creator:
- Feng, Z.-Z., Yao, F.-F., Chen, Z., Wang, X.-K., Zheng, Q.-W., and Feng, Z.-W.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- apparent quantum yield, diurnal pattern of O3, net photosynthetic rate, irradiance, stomatal conductance, and yield components
- Language:
- Multiple languages
- Description:
- To assess photosynthesis and yield components' response of field-grown wheat to increasing ozone (O3) concentration (based on diurnal pattern of ambient O3) in China, winter wheat (Triticum aestivum L.) cv. Jia 403 was planted in open top chambers and exposed to three different O3 concentrations: O3-free air (CF), ambient air (NF), and O3-free air with additional O3 (CF+O3). Diurnal changes of gas exchange and net photosynthetic rate (PN) in response to photosynthetic photon flux density (PPFD) of flag leaves were measured at the filling grain stage, and yield components were investigated at harvest. High O3 concentration altered diurnal course of gas exchange [PN, stomatal conductance (gs), and intercellular CO2 concentration (Ci)] and decreased significantly their values except for Ci. Apparent quantum yield (AQY), compensation irradiance (CI), and saturation irradiance (SI) were significantly decreased, suggesting photosynthetic capacity was also altered, characterized as reduced photon-saturated photosynthetic rate (PNmax). The limit of photosynthetic activity was probably dominated by non-stomatal factors in combination with stomatal closure. The significant reduction in yield was observed in CF+O3 treatment as a result of a marked decrease in the ear length and the number of grains per ear, and a significant increase in the number of infertile florets per ear. Even though similar responses were also observed in plants exposed to ambient O3 concentration, no statistical difference was observed at current ambient O3 concentration in China. and Z.-Z. Feng ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4228. Response of intact cyanobacterial cells and their photosynthetic apparatus to Cd2+ ion treatment
- Creator:
- Tůmová, E. and Sofrová, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll, dodecylmaltoside, heavy metals, photochemical activities, photosynthetic pigment content, photosystems 1 and 2, Synechococcus, and toxic metals
- Language:
- Multiple languages
- Description:
- Intact cells of Synechococcus elongatus were treated with different concentrations (0.1 and 1.0 mM = Cd0.1, Cd1.0) of CdCl2 for 24 h. Cd0.1 treatment stimulated growth of the cell culture and chlorophyll (Chl) a concentration in the culture. Cd1.0 inhibited both the above mentioned parameters. The oxygen evolving activity of intact cells (H2O → BQ) as well as of isolated thylakoid membranes, TM (H2O → DCPIP; H2O → PBQ + FeCy) decreased after 24 h of Cd1.0 cultivation to 7 %. Photosystem 1 (PS1) activity was less sensitive to the effect of Cd2+ than PS2 activity. CdCl2 concentration in cultivation media after 24 h of cultivation proved that the cyanobacterium cells take up these ions to a large extent from the cultivation medium. After 24 h of the Cd1.0 treatment only 12 % of the amount of Cd2+ originally added to the cultivation medium was found. The ratio of external-antenna pigments, phycocyanin, and allophycocyanin to Chl increased approximately twofold with growing Cd2+ concentration in the cultivation medium. This ratio was found in both TM and dodecylmaltoside extracts. and E. Tůmová, D. Sofrová.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4229. Response of invasive Chromolaena odorata and two coexisting weeds to contrasting irradiance and nitrogen
- Creator:
- Quan, G. M., Mao, D. J., Zhang, J. E., Xie, J. F., Xu, H. Q., and An, M.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, gas exchange, invasive species, irradiance, nitrogen supply, pigment, 2, and 581
- Language:
- Multiple languages
- Description:
- a1_Chromolaena odorata is a widespread exotic weed in southern China and other regions of the world. To better understand its invasive strategies, we compared leaf pigment contents and gas-exchange traits of the invader with its two coexisting species (native Urena lobata and invasive Bidens pilosa) under combined conditions of irradiance (full, medium, and low) and nitrogen (full, medium, and low) supplies. The chlorophyll (Chl) a+b content of U. lobata was the highest and the Chl a/b ratio of C. odorata was the lowest among the three weed species. In most treatments, leaf pigment, light-saturated photosynthetic rate (P max), and light saturation point (LSP) of all the species increased, while their Chl a/b ratios decreased with the increasing nitrogen. The P max and LSP of U. lobata were greater than those of the coexisting weeds under full irradiance (FI), but significantly declined with the decreasing irradiance. The invasive weeds, especially C. odorata, showed lower P max and LSP under FI, but they showed slight decrease under low irradiance. Compared to U. lobata, C. odorata exhibited the lower light compensation point (LCP) in most treatments, higher LSP under low and medium irradiance, and lower dark respiration rate under FI. In addition, all the three species showed similar responses to different irradiance and nitrogen conditions, mean phenotypic plasticity index (MPPI) of most photosynthetic variables of the two invasive species was lower than that of U. lobata. These results suggested that C. odorata behaved as a facultative shadetolerant weed, being able to grow in moderately sheltered environments; the lower MPPI might be one of the important competitive strategies during its invasion. However, its invasion should be limited to some very shady habitats., a2_In the field, control should be mainly directed against populations growing in the open or nutrient-rich habitats, where its expansion speed could be much faster. Deep shade by intact canopies or luxuriant forests might be an effective barrier against its invasion., G. M. Quan, D. J. Mao, J. E. Zhang, J. F. Xie, H. Q. Xu, M. An., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4230. Response of photosynthesis and chlorophyll fluorescence quenching to leaf dichotocarpism in Ligustrum vicaryi, an ornamental herb
- Creator:
- Yang, Y. Q., Yi, X. F., and Prasad, P.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll, CO2 uptake, energy utilization, photoprotection, sunflecks, and thermal dissipation
- Language:
- Multiple languages
- Description:
- Net photosynthetic rate of yellow upper leaves (UL) of Ligustrum vicaryi was slightly, but not significantly higher than that of green lower leaves (LL). Diurnally, maximum photochemical efficiency of photosystem 2, PS2 (Fv/Fm) of LL did not significantly decline but the UL showed fairly great daily variations. Yield of PS2 of UL showed an enantiomorphous variation to the photosynthetically active radiation and was significantly lower than in the LL. Unlike Fv/Fm, the efficiency of energy conversion in PS2 and both non-photosynthetic and photosynthetic quenching did not differ in UL and LL. Significant differences between UL and LL were found in contents of chlorophyll (Chl) a, b, and carotenoids (Car) and ratios of Chl a/b, Chl b/Chl (a+b), and Car/Chl (a+b). Leaf colour dichotocarpism in L. vicaryi was mainly caused by different photon utilization; sunflecks affected the LL. and Y. Q. Yang, X. F. Yi, P. Prasad.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public