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62. Comparison of parameters estimated from A/Ci and A/Cc curve analysis
- Creator:
- Zeng, W., Zhou, G. S., Jia, B. R., Jiang, Y. L., and Wang, Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, A/Ci curve analysis, A/Cc curve analysis, mesophyll conductance, parameter estimation, and photosynthesis
- Language:
- Multiple languages
- Description:
- The parameters estimated from traditional A/Ci curve analysis are dependent upon some underlying assumptions that substomatal CO2 concentration (Ci) equals the chloroplast CO2 concentration (Cc) and the Ci value at which the A/Ci curve switches between Rubisco- and electron transport-limited portions of the curve (Ci-t) is set to a constant. However, the assumptions reduced the accuracy of parameter estimation significantly without taking the influence of Ci-t value and mesophyll conductance (gm) on parameters into account. Based on the analysis of Larix gmelinii's A/Ci curves, it showed the Ci-t value varied significantly, ranging from 24 Pa to 72 Pa and averaging 38 Pa. t-test demonstrated there were significant differences in parameters respectively estimated from A/Ci and A/Cc curve analysis (p<0.01). Compared with the maximum ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax), the maximum electron transport rate (Jmax) and Jmax/Vcmax estimated from A/Cc curve analysis which considers the effects of gm limit and simultaneously fits parameters with the whole A/Cc curve, mean Vcmax estimated from A/Ci curve analysis (Vcmax-Ci) was underestimated by 37.49%; mean Jmax estimated from A/Ci curve analysis (Jmax-Ci) was overestimated by 17.8% and (Jmax-Ci)/(Vcmax-Ci) was overestimated by 24.2%. However, there was a significant linear relationship between Vcmax estimated from A/Ci curve analysis and Vcmax estimated from A/Cc curve analysis, so was it Jmax (p<0.05). and W. Zeng ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
63. Comparison of photosynthesis and antioxidative protection in Sedum album and Sedum stoloniferum (Crassulaceae) under water stress
- Creator:
- Habibi, G. and Hajiboland, R.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, CAM-cycling, hydrogen peroxide, Δtitratable acidity, 2, and 58
- Language:
- Multiple languages
- Description:
- a1_Photosynthetic gas exchange, dry mass production, water relations and inducibility of crassulacean acid metabolism (CAM) pathway as well as antioxidative protection during the C3-CAM shift were investigated in Sedum album and Sedum stoloniferum from Crassulaceae under water stress for 20 days. Leaf relative water content (RWC), leaf osmotic and water potential decreased with increasing water stress in both studied species. Significant reduction in dry matter production and leaf thickness was detected only in S. stoloniferum after 20-d water stress. Δtitratable acidity and phosphoenolpyruvate carboxylase (PEPC) activity in S. album responded to drought at early stages of stress treatment, continued to increase throughout the entire stress period and reached levels 15 times higher than those in well-watered plants. In S. stoloniferum, however, both parameters responded later and after a transient increase declined again. In S. stoloniferum, in spite of increase by drought stress, net night-time CO2 assimilation was negative resembling a C3-like pattern of gas exchange. Catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) activities increased in plants subjected to mild water stress while declined as the stress became severe. Although malondialdehyde (MDA) content was higher in drought-stressed S. stoloniferum, the increase in the concentration of hydrogen peroxide (H2O2) that may act as a signal for C3-CAM transition was higher in S. album compared with S. stoloniferum. In drought-stressed plants, SOD activity showed a clear diurnal fluctuation that was more steadily expressed in S. album. In addition, such pattern was observed for CAT only in S. album. We concluded that temporal and diurnal fluctuation patterns in the activity of antioxidant enzymes depended on duration of drought stress and was related to the mode of photosynthesis and degree of CAM induction., a2_According to our results, S. stoloniferum developed a low degree of CAM activity, e.g. CAM-cycling metabolism, under drought conditions., G. Habibi, R. Hajiboland., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
64. Comparison of the photosynthetic characteristics of four Lycoris species with leaf appearing in autumn under field conditions
- Creator:
- Liu, K., Tang, C. F., Zhou, S. B., Wang, Y. P., Zhang, D., Wu, G. W., and Chang, L. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, chlorophyll fluorescence, diurnal change, Lycoris species, photosynthesis, 2, and 58
- Language:
- Multiple languages
- Description:
- The diurnal trends of gas exchange and chlorophyll fluorescence parameters in four Lycoris species (L. houdyshelii, L. aurea, L. radiata var. pumila and L. albiflora) were determined and compared with a portable photosynthesis analysis system. Our study revealed that L. houdyshelii had the lowest light compensation point (LCP), while the other three species had higher LCP (12.37-14.99 μmol m-2 s-1); L. aurea had the highest light saturation point (LSP) (1,189 μmol m-2 s-1), and L. houdyshelii and L. albiflora had lower LSP with the values being 322 and 345 μmol m-2 s-1, respectively, and L. radiata var. pumila showed the intermediate LSP. Both the species L. houdyshelii and L. albiflora exhibited a typical and obvious decline in net photosynthetic rate (PN) during midday, which was not observed in L. aurea. This indicated a possible photoinhibition in L. houdyshelii and L. albiflora as the ratio of variable to maximum fluorescence (Fv/Fm) values were higher in these two species. The minimal fluorescence (F0) values were lower in L. aurea and L. radiata var. pumila. The diurnal changes of transpiration rate (E) in all four species presented only one peak, appearing between 11:00 h or 13:00 h. By using simple correlation analyses, it was observed that the environmental factors affecting PN were different among four species and the main factors were photosynthetic photon flux density (PPFD) and relative humidity especially for L. aurea and L. radiata. The results of studying indicated that the four species could be divided into two groups. The species L. radiata var. pumila and L. aurea were more adapted to a relatively high irradiance, and L. houdyshelii and L. albiflora could be grown in moderate-shade environment in order to scale up their growth and productivity., K. Liu ... [et al.]., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
65. Compensatory growth and photosynthetic responses of Pharbitis purpurea seedlings to clipped cotyledon and second leaf
- Creator:
- Zheng, W., Yang, J. Y., Luan, Z. H., Wang, P., Zhang, H. X., and Zhou, D. W.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, clipping, compensatory growth, photosynthesis, primary leaf, remnant cotyledon, and seedling
- Language:
- Multiple languages
- Description:
- Leaf tissue damaging to seedlings can limit their subsequent growth, and the effects may be more extensive. Compensatory photosynthesis responses of the remnant cotyledon and primary leaf of Pharbitis purpurea to clipping and the effect of clipping on seedling growth were evaluated in a pot-cultivated experiment. Three treatments were conducted in the experiment, which were clipped cotyledon (CC), clipped second leaf (CL), and control group (CG). The area, thickness, mass, and longevity of the remaining cotyledon of CC exhibited over-compensatory growth. In contrast, seedlings of CC had under-compensatory growth in seedling height, root length, seedling mass, and root to shoot ratio. However, the traits of remnant cotyledon and seedling in CL treatment exhibited equal-compensatory growth. Net photosynthetic rate of the cotyledon of CC was significantly higher than those of CL and CG treatments, and the diurnal changes in photosynthetic rates showed significantly different patterns which were unimodal curve (CC) and bimodal curve (CL and CG), respectively. There was no significant difference between CL and CG treatment. Net photosynthetic rate of the primary leaf of CL was significantly higher than that of CG treatment. However, the photosynthetic rates of primary leaves of CL and CG treatments showed similar photosynthetic patterns characterized by a bimodal curve. P. purpurea seedlings used a compensatory growth strategy in the remaining cotyledon or the primary leaf to resist leaf loss and minimize any adverse effects. and W. Zheng ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
66. Consequences of light absorptance in calculating electron transport rate of desert and succulent plants
- Creator:
- Stemke, J. A. and Santiago, L. S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, chlorophyll fluorescence, crassulacean acid metabolism, desert plants, photosynthesis, and succulence
- Language:
- Multiple languages
- Description:
- The proportional light absorptance by photosynthetic tissue (α) is used with chlorophyll (Chl) fluorescence methods to calculate electron transport rate (ETR). Although a value of α of 0.84 is often used as a standard for calculating ETR, many succulent plant species and species with crassulacean acid metabolism (CAM) have photosynthetic tissues that vary greatly in color or are highly reflective, and could have values of α that differ from 0.84, thus affecting the calculation of ETR. We measured ETR using Chl fluorescence and α using an integrating sphere in 58 plant species to determine the importance of applying a measured value of α when calculating ETR. Values of α varied from 0.55-0.92 with a mean of 0.82 across species. Differences between ETR values calculated with measured α values ranged from 53% lower to 12% greater than ETR values calculated with a standard α value of 0.84 and were significantly different in 39 out of 58 species. While measurements of ETR using Chl fluorescence represent a rapid and effective assessment of physiological performance, the value of α needs to be considered. Measurements of α, especially on species with light-colored or reflective photosynthetic tissue, will allow more accurate determination of photosynthesis in succulent and CAM species. and J. A. Stemke, L. S. Santiago
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
67. Contrasting leaf characteristics of trees and lianas in secondary and mature forests in southwestern China
- Creator:
- Han, L., Xie, L.-J., Dai, K.-J., Yang, Q., and Cai, Z.-Q.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, leaf morphology, liana, photosynthetic rate, secondary forest, and tree
- Language:
- Multiple languages
- Description:
- We compared variation in sun-canopy leaf anatomy, morphology and photosynthetic rates of coexisting woody species (trees and lianas) in an 8-year-old secondary forest (SF) and mature forest (MF) in the wet season in Xishuangbanna, SW China. Variability of leaf traits of 66 species within growth-form groups in each forest was quantified using coefficients of variation (CV). For the mean values, the woody species in the SF had significantly higher leaf thickness and stomatal density, but lower nonmesophyll/mesophyll ratios than those in the MF. The average leaf area and leaf mass area (LMA) in the studied woody species did not change greatly during the successional process, but differed significantly between the growth forms, with trees having higher values than lianas. The light-saturated photosynthetic rate per unit leaf area (Aa) of the woody species in the SF ranged from 11.2 to 34.5 μmol m-2 s-1, similarly to pioneer tree species from literature data in southeast Asia. The Aa and photosynthetic nitrogen-use efficiency (PNUE) were significantly higher than those in the MF; whereas Aa in the MF ranged between 9 to 21 μmol m-2 s-1, with similar values between lianas and trees. For all woody species in both SF and MF, there were no significant differences in the average values of the CV of all measured variables for both lianas and trees. However, considerable variation in leaf anatomy, morphology, and photosynthetic rates within both growth forms and forests existed, as well as substantial variation in leaf size and stomatal density. We concluded that the tropical woody species formed a heterogeneous functional group in terms of leaf morphology and physiology in both secondary and mature forests. and L. Han ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68. Contribution of leaf nitrogen to photosynthetic gas exchange in contrasting rice (Oryza sativa L.) cultivars during the grain-filling period
- Creator:
- Shimoda, S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, carbon discrimination, nitrogen supply, photosynthetic CO2 assimilation, stomatal conductance, 2, and 58
- Language:
- Multiple languages
- Description:
- Photosynthetic parameters and leaf carbon isotope composition (δ13C) in contrasting rice genotypes in relation to supplemental nitrogen (N) application and water management during the grain-filling period were compared. The changes in stomatal conductance (gs) and ratio of intercellular to ambient CO2 mole fraction (Ci/Ca) depended on the leaf nitrogen concentration (leaf N) in both ‘Hinohikari’ (temperate japonica genotype) and ‘IR36’ (indica genotype). In ‘Hinohikari’, δ13C reflects photosynthetic gas exchange during the grain-filling period, which is indicated by the significant response of δ13C to leaf N. In contrast, in ‘IR36’ δ13C did not depend on leaf N. This varietal difference in δ13C to leaf N can be attributed to a difference in the timing of leaf senescence. In ‘IR36’, leaf N and photosynthetic parameters decreased more rapidly, indicating earlier senescence and a shorter grain-filling period in comparison with ‘Hinohikari’. The significant increase in shoot dry mass in ‘Hinohikari’ resulting from supplemental N application, compared with nonsignificant effect observed in ‘IR36’, suggests that the timing of senescence in relation to the grainfilling period has a preponderant influence on productivity., S. Shimoda., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
69. Coordinate expression of light-harvesting chlorophyll a/b gene family of photosystem II and chlorophyll a oxygenase gene regulated by salt-induced phosphorylation in Dunaliella salina
- Creator:
- Chen, W. M., Jin, N., Shi, Y., Su, Y. Q., Fei, B. J., Li, W., Qiao, D. R., and Cao, Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, Dunaliella salina, high salinity, light-harvesting chlorophyll a/b proteins, phosphorylation, and simultaneous regulation
- Language:
- Multiple languages
- Description:
- As a stress factor, salt induces the phosphorylation of light-harvesting chlorophyll (Chl) a/b proteins (LHCII) in Dunaliella salina. In this study, we found that the salt-induced phosphorylation of LHCII was not affected by phosphatase, and that salt simultaneously regulated both the phosphorylation of LHCII and the expression of genes encoding light-harvesting Chl a/b proteins of photosystem II (lhcb) and the gene encoding Chl a oxygenase (cao) in dark-adapted D. salina. The mRNA accumulation patterns of lhcb and cao were similar, which further affected the size of LHCII and the ratio of Chl a to Chl b. Therefore, we inferred this simultaneous regulation is one of the mechanisms of D. salina to adapt to the high-salinity environment. and W. M. Chen ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
70. Cristo Redentor z pohledu botanického
- Creator:
- Miloslav Studnička
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Biologické vědy, botanika, rostlinné endemity, fyziologie rostlin, botany, native plants, plant physiology, Brazílie, Brasil, Corcovado, Tijuca, 2, and 57/59
- Language:
- Czech
- Description:
- Článek přibližuje botanickou exkurzi do Brazílie na horu Corcovado (710 m n. m.), nacházející se u pobřeží Atlantského oceánu, na vrcholu se sochou Krista Vykupitele (Cristo Redentor). Území leží v národním parku Tijuca, který byl zřízen na ochranu tropického deštného lesa, zde nazývaného mata atlântica (atlantský les). Autor představuje některé významné skupiny zdejší flóry, vybrané endemické taxony či rostliny se zajímavou životní strategií., This article presents a botanical excursion up Mount Corcovado (710 m a. s. l.) on the Atlantic coast of Brazil, with the statue of Christ the Redeemer (Cristo Redentor) at the top. The territory belongs to the Tijuca National Park, established to protect the tropical rain forest - called mata atlântica (Atlantic forest). Several important groups of local flora, selected endemic taxons and also plants with interesting life strategies are presented here., and Miloslav Studnička.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public