Considerable increase in net photosynthetic rates ribulose-l-5-bisphosphate carboxylase (RuBPC) and phosphoenolpyruvate carboxylase (PEPC) activities, and pigment contents was observed in Helianthus annuus L. plants affected by different types of N-fertilization, but no cultivar variability was found. and water use efficiency (WUE) were enhanced strongly when the plants were treated with a combined compost (12N-12K-12P) or urea while manure induced a rather weak effect. The carboxylase activities changed wifli the N treatment and they were higly correlated with and WUE (r > 0.9). The RuBPC/PEPC ratios fell drastically in urea and 12N-12K-12P treated plants.
Photosynthetic characteristics were compared between plants of low altitude (LA) grown at LA (Palampur; 1 300 m) and at high altitude, HA (Kibber; 4 200 m), and plants naturally occurring at different altitudes (Palampur, 1 300 m; Palchan, 2 250 m; and Marhi, 3 250 m). Net photosynthetic rate (PN) was not significantly different between altitudes. However, the slopes of the curve relating PN to intercellular CO2 concentration (Ci) were higher in plants at Palchan, Marhi, and Kibber compared to those at Palampur, indicating that plants had higher efficiency of carbon uptake (the initial slope of PN/Ci curve is an indication) at HA. They had also higher stomatal conductance (gs), transpiration rate, and lower water use efficiency at HA. gs was insensitive to photosynthetic photon flux density (PPFD) for plants naturally occurring at Palampur, Palchan, and Marhi, whereas plants from LA grown at Palampur and Kibber responded linearly to increasing PPFD. Insensitivity of gs to PPFD could be one of the adaptive features allowing wider altitudinal distribution of the plants. and N. Kumar, S. Kumar, P.S. Ahuja.
High level of phosphoenolpyruvate carboxylase (PEPC) gene was stably inherited and transferred from the male parent, PEPC transgenic rice, into a female parent, japonica rice cv. 9516. Relative to the female parent, the produced JAAS45 pollen lines exhibited high PEPC activity (17-fold increase) and also higher photosynthetic rates (about 36 %-fold increase). The JAAS45 pollen lines were more tolerant to photoinhibition and to photo-oxidative stress. Furthermore, JAAS45 pollen lines, as well as their male parent, were tested to exhibit a limiting C4 cycle by feeding with exogenous C4 primary products such as oxaloacetate (OAA). Thus the PEPC gene and photosynthetic characteristics of PEPC transgenic rice could be stably transferred to the hybrid progenies, which might open a new breeding approach to the integration of conventional hybridization and biological technology. and L. Ling, B. J. Zhang, D. M. Jiao.
Sodium chloride salinity had enhanced the photosynthetic rate, photosystem 2 activity and chlorophyll synthesis in isolated leaf cells of Ipomoea pescaprae up to 200 mM NaCl. The salt treated plants did not show any shift in the mode of photosynthesis.
Chlorophyll content, photosystem 2 functioning (Fv/Fm, Fv/F0), activity of ribulose-1,5-bisphosphate carboxylase/oxygenase, and net photosynthetic rates (PN) of flag leaf blade, sheath, peduncle, and ear organs were assessed in large-ear type (Pin 7) and small-ear type (ND93) wheat cultivars. Some differences were found in photosynthetic properties between different green plant parts, the values of all studied parameters in ear parts being higher in Pin7 than in ND93. Furthermore, ear surface areas and ear PN in 26 wheat genotypes measured at anthesis showed highly significant positive correlation with grain mass per ear. Hence a greater capability of ear photosynthesis may result in a greater grain yield in large-ear type cultivars. and Zhi-Min Wang, Ai-Li Wei, Dan-Man Zheng.
Responses of leaf gas exchange, fluorescence emission, chlorophyll concentration, and morpho-anatomical features to changes in photosynthetic photon flux density (PPFD) were studied in three wild ornamental species of Passiflora L. to select sun and shade species for landscaping projects. Artificial shade was obtained with different shading nylon nets, under field conditions, which allowed the reduction of 25, 50, and 75% of global radiation, along with a control treatment under full sunlight. For Passiflora morifolia the highest mean values of light-saturated net photosynthetic rate (PNmax) and light compensation point (LCP) were observed at 50 and 25% shade, respectively, while the highest values of dark respiration rate (RD) and apparent quantum yield (α) were observed at 75% shade. For Passiflora suberosa litoralis the highest value of P max was observed at full sunlight. The highest mean values for Pmax, RD, and LCP for Passiflora palmeri var. sublanceolata were obtained at 25% shade. The highest values of net photosynthetic rate (PN) for P. morifolia, P. palmeri var. sublanceolata, and P. suberosa litoralis were 21.09, 16.15, and 12.36 μmol(CO2) m-2 s-1, observed at 50 and 75% shade and full sunlight, respectively. The values of the minimal chlorophyll fluorescence (F0) were significantly different in P. suberosa litoralis and P. palmeri var. sublanceolata, increasing with the increase of the irradiance. In contrast, the values of maximum photochemical efficiency of PSII (Fv/Fm) were significantly different only in P. suberosa litoralis, being higher at 75%, progressively reducing with the increase of PPFD levels. The total concentration of chlorophyll (Chl) was higher in shaded plants than in the ones cultivated in full sunlight. On the other hand, the values of Chl a/b ratio were reduced in shaded plants. A significant effect of shade levels on leaf area (LA) and specific leaf area (SLA) was found for the three species, whose highest mean values were observed at 75% shade. The thickness of foliar tissues was significantly higher for the three species at full sunlight and 25% shade. These results suggested that P. morifolia and P. palmeri var. sublanceolata appeared to be adapted to moderate shade conditions. P. suberosa litoralis presented higher plasticity to greater variation of the irradiance levels, while the photoinhibition was one of the limiting factors for this species at full sunlight. and M. V. Pires ... [et al.]
Charactenstícs of the pigment apparatus were studied in plants grown from tubers of the oř 3’’^ doně generation of two cultivars of potato (Solanum tuberosum L) transformed with Agrobacterium tumefaciens strains. The cv. Zvíkov carries pRiA4b T-DNA of A. rhizogenes and the vector plasmid pGA472 T-DNA carrying the gene for kanamycin resistance. The cv. Kamýk carries the vector plasmid pCB1339 which contains the kanamycin resistance gene and the cytokinin synthesis gene. In the field experiments, the plant dry matter, the relative water content, the chlorophyll (Chl) a and b contents, the Chl a/b ratio and the course of slow Chl fluorescence induction curves were not signifícantly different in transformed and control plants. The amoímt of the Chl-protein complexes of the reaction centres of both photosystems separated by electrophoresis was similar for both transformed and control plants. Howevér, the content of oligomeric light-harvesting complex was significantly higher in both the transformants.
Photosynthetic and growth characteristics of the control potato plants cv. Zvíkov and those transformed by Agrobacterium were compared during their cultivation in vitro in agar medium with 1 % saccharose, after having been transplanted into pots with soil, or growing from tubers in soil. The average leaf aiea, fresh and dry matter, chlorophyll a and b ratio, and contents calculated per fresh and diy matter of the leaf area were significantly higher in the control plants raised from tubers and in vitro cultivated than in the transplanted ones. The significant increase in oxygen evolution by leaf fragments was found only in the control potato plants raised from tubers. Differences between photochemical activities of chloroplasts isolated from control and transformed plants were statistically significant only when calculated per fresh leaf matter. Chloroplasts from transformed potato plants grown from tubers and from those cultivated in vitro exhibited higher activities of photosystems (PS) 2 and PS 1 independently on the donors and acceptors of electrons ušed. On the contrary, higher activities of both photosystems were found in chloroplasts isolated from the control plants transferred to soil.
Photosynthetic parameters were studied in Arbutus unedo L. trees growing at either ambient (AC) or elevated EC (mean 465 µmol mol-1) CO2 concentration near a natural CO2 vent in Orciatico, Italy Diurnal courses of net photosynthetic rate (PN), ratio of variable to maximum chlorophyll fluorescence (Fv/Fm), and quantum yield of electron transport through photosystem 2 (Φ2) were measured on sun and shade leaves. The contents of N, C, Ca, K, P, and chlorophyll (Chl) and specific leaf area (SLA) in these leaf categories were also determined. A morning peak and midday depression of PN were found for both AC and EC sun leaves. Long-term EC caused little or no down-acclimation of PN in sum leaves. The estimate of total daily CO2 uptake was lower in AC leaves than in EC leaves. In shade leaves, it reached up to 70 % of the value of sun leaves. The Fv/Fm ratio showed decreasing trend in the morning, reached a minimum at midday (90 % of dawn value), and then increased in the afternoon. The EC had no effect on Fv/Fm either in sun or shade leaves. Plants grown near the CO2 spring had lower Chl content, higher SLA, and higher Ca and K contents than plants grown under AC. and M. Barták, A. Raschi, R. Tognetti.
Two yellow rice mutants VG28-1 and VG30-5 were obtained during the tissue culture process from a rice plant (cv. Zhonghua No.11 japonica) with inserted maize Ds transposon element. Absorption spectra and pigment composition showed that two mutants had no chlorophyll (Chl) b and lower Chl a content in comparison to the wild type (WT). Net photosynthetic rate (PN), total electron transport rate (JF), photochemical quenching (qp), quantum yield of PS2 dependent non-cyclic electron transport (ΦPS2), fraction of Prate, and leaf area were lower but Fv/Fm and apparent quantum yield (AQY) remained at similar levels as in the WT plant. Xanthophyll cycle pool size (V+A+Z) on a Chl basis, and de-epoxidation state were enhanced in the mutants. The mutants had larger amounts of soluble protein and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO), especially the small subunit of RuBPCO, than WT. The characteristics of two rice mutants differed somewhat from the other common Chl b-less mutants originating from mutagenic agent treatments. and Zhi-Fang Li ... [et al.].