Warming winter and atmospheric nitrogen (N) deposition are expected to have effects on net primary production (NPP) of Chinese fir (Cunninghamia lanceolata) plantation and implications for plantation carbon sequestration. The effects of nongrowing-season warming on plant morphological and physiological traits were investigated in a greenhouse experiment with two-year-old C. lanceolata seedlings. Elevated temperature (ET) during the nongrowing season significantly increased the net photosynthetic characteristics. The strongest effects occurred during warming period from 1 December 2014 to 1 February 2015 (W1). Moreover, the carbohydrate concentration was elevated due to the warming during W1, but it declined during four months of the warming (from 1 December 2014 to 1 April 2015, W2). The seedlings kept under N deposition (CN) showed a positive effect in all the above-mentioned parameters except δ13C. Significant interactions between ET and N deposition were observed in most parameters tested. At the end of the experiment (W2), the seedlings exposed to a combined ET and N deposition treatment exhibited the highest carbon contents. Our results showed that N deposition might ameliorate the negative effects of the winter warming on the carbon content., L. Yu, T. F. Dong, Y. B. Lu, M. Y. Song, B. L. Duan., and Obsahuje bibliografii
Vegetation in grasslands is changing at an unprecedented rate. In the Nebraska Sandhills, this shift is attributed in part to encroachment of the woody species Juniperus virginiana. We investigated changes in resource availability and their feedback on seasonal trends in photosynthetic characteristics of J. virginiana trees scattered in open grasslands vs. a dense 57-year-old stand. Dense stand exhibited lower volumetric soil water content, NH4+, NO3-, and δ13C, as well as foliage δ13C, δ15N, and N content, compared to grasslands. Water potential was higher in trees in grasslands compared to dense stand. J. virginiana in dense stand exhibited similar trends to trees in grasslands for net photosynthetic rate (PN), stomatal conductance, transpiration, maximum photochemical efficiency of PSII, maximum carboxylation velocity, and maximum rate of electron transport. PN peaked early summer and declined in the fall, with trees in open grasslands lagging behind those in dense stand. Plasticity of this species may place it at a competitive advantage in the Sandhills, further altering grasslands vegetation and ecosystem processes., J. Msanne, T. Awada, N. M. Bryan, W. Schacht, R. Drijber, Y. Li, X. Zhou, J. Okalebo, D. Wedin, J. Brandle, J. Hiller., and Obsahuje bibliografii
The influence of different leaf-to-fruit (l-t-f) ratios on leaf net photosynthetic rate (PN) and fruit characteristics in Olea europaea L. cv. Frantoio was evaluated in 2001 and 2002. In both years, at the end of June, at the end of July, and in mid-September (first, second, and third time of treatment, respectively), defoliation or fruit thinning were performed to give l-t-f ratios of 1/1, 3/1, 5/1, and 7/1 (about 5.1, 15.3, 25.6, and 35.8 cm2 of leaf area per fruit, respectively) on girdled and ungirdled peripheral shoots. PN showed substantial seasonal and diurnal variations. In ungirdled shoots, no differences due to the different l-t-f ratios were observed, whereas in girdled shoots PN tended to be lower in shoots with a high l-t-f ratio. In general, the values of leaf transpiration rate (E), stomatal conductance (gs), sub-stomatal CO2 concentration (Ci), and dark respiration rate (RD) were associated with those of PN. The starch and reducing sugar contents and area leaf dry mass (ADM) tended to be higher in leaves on girdled shoots with high l-t-f ratio, whereas in ungirdled shoots no differences related to the different l-t-f ratios were observed. The higher saccharide content in the leaves and the lower PN, in the presence of a high Ci, observed in girdled shoots with a high l-t-f ratio suggests that the depression in PN in these shoots may be the result of a feedback inhibition of the photosynthetic mechanism that regulates such a process. The l-t-f ratio did not have a substantial effect on fruit drop. In ungirdled shoots, the different l-t-f ratios did not produce significant differences in terms of fruit growth and leaf dry matter and saccharide contents, whereas in girdled shoots fruit growth increased as the l-t-f ratio increased, particularly when treatments were applied at the initial stage of fruit development. The percentage of oil in the pulp, on a dry matter basis, was not substantially influenced by girdling and l-t-f ratio. The abundant availability of assimilates seemed to cause earlier fruit ripening and, at the same time, retard fruit senescence (fruit detachment force). Shoot growth was slightly reduced by girdling. The abundant availability of assimilates, induced by girdling associated with high l-t-f ratio, stimulated flower induction. and P. Proietti, L. Nasini, F. Famiani.
The rubber tree (Hevea brasiliensis) is an important tropical crop with a high economic value that has been successfully cultivated in Xishuangbanna, China. Xishuangbanna has a long dry season (November-February) with cold nights and frequent fog events. Thus, it is important to select chilling-tolerant cultivars in order to understand better the role of fog in protecting rubber tree from chilling-induced photodamage. In this study, we examined the photosynthetic responses of six rubber tree cultivars (Lan 873, Yunyan 77-2, Yunyan 77-4, GT1, Reken 523, and Reyan 733-97) to night-chilling stress (0, 5, and 10°C) and two different irradiances (100 and 50% of full sunlight). Our results showed that all six cultivars could withstand nights at 10°C for three days, while night chilling at 0 and 5°C impaired photosynthesis, which was indicated by photoinhibition, decrease of soluble protein content, and accumulation of malondialdehyde. Reken 523 and Reyan 733-97 were more sensitive to night chilling than other cultivars. Low irradiance (50% of full sunlight) after the chilling treatment apparently mitigated the effect of night-chilling stress. It indicates that frequent fog events after cold nights might greatly contribute to the success of rubber tree cultivation in Xishuangbanna., Y.-H. Tian, H.-F. Yuan, J. Xie, J.-W. Deng, X.-S. Dao, Y.-L. Zheng., and Seznam literatury
Water stress usually impairs photosynthesis and plant growth. Acacia tortilis subsp. raddiana is well adapted to dry environments. The aim of the present study was to determine the impact of a progressive decrease in soil water content on photosynthetic-related parameters at the young seedling stage. Drought-induced plant responses occurred according to two types of kinetics. Water potential, stomatal conductance, and transpiration rates were rapidly affected by a decrease in soil water content, while chlorophyll fluorescence-related parameters and chlorophyll concentrations decreased only when soil water content was lower than 40%. The maximal efficiency of PSII photochemistry in the dark-adapted state remained unaffected by the treatment, whatever the stress duration. A. raddiana accumulated high concentrations of soluble sugars in relation to a stress-induced early stimulation of sucrose-phosphate synthase activity, while stimulation of invertase and sucrose synthase led to fructose accumulation only at the end of the stress period. We suggested that sugar accumulation may be involved in osmotic adjustment and protection of stressed tissues. A. raddiana was thus able to protect its photosynthetic machinery under drought conditions and may be considered as a promising species for revegetation of dry areas., S. Kebbas, S. Lutts, F. Aid., and Obsahuje bibliografii
Anticipating warming related to climate change, commercial mango plantations in China have been shifting from lower to higher elevations. Such a practice may expose mangoes to climatic conditions that could affect photosynthesis. Photosynthesis research on mango has previously examined mature plantations but exploring adequate functions before the time of fruit production is necessary for later crop success. Therefore, we established two main commercial mango cultivars, Tainong No. 1 and Jinhuang, at 450 m and 1,050 m and examined their photosynthetic performance. Our results showed that photosynthetic capacity parameters, including maximum photosynthetic rate, apparent quantum yield, maximum carboxylation rate, and photosynthetic electron transport rate, were significantly different between cultivars due to elevation and positively correlated with leaf nitrogen per area. Moreover, the seasonal gas exchange of the two cultivars showed variations due to elevation, particularly during the warmer seasons. Therefore, elevation affects the photosynthetic performance of these mango cultivars.
The present study was conducted to determine the effect of exogenous application of brassinolide (BR) on Leymus chinensis grown under shade, i.e., control (100% natural light), mild shade (70% natural light), and moderate shade (50% natural light). Shade substantially enhanced the plant growth, synthesis of photosynthetic pigments, photosynthetic efficiency, and chlorophyll (Chl) fluorescence attributes of L. chinensis as compared with control. The order of increase was mild shade > moderate shade > natural light except Chl content, where the order of increase was moderate shade > mild shade > natural light. Likewise, application of BR resulted in further exacerbation of plant height, plant fresh and dry mass, but less in case of Chl and carotenoids contents, gas-exchange characteristics, and Chl fluorescence attributes. The results conclude that shade significantly enhanced plant growth through alterations in physiological attributes of L. chinensis, while, application of BR may not further improve the plant growth under shade., A. J. Yang, S. A. Anjum, L. Wang, J. X. Song, X. F. Zong, J. Lv, A. Zohaib, I. Ali, R. Yan, Y. Zhang, Y. F. Dong, S. G. Wang., and Obsahuje bibliografii
Agronomic traits, photosynthetic pigments, gas exchange, and chlorophyll (Chl) fluorescence parameters of red stem buckwheat (Fagopyrum dibotrys Hara) mutants induced by γ-radiation were compared with green control at seedling stage. Plant height, number of first-class branches, and rhizome biomass were inhibited significantly (p<0.01). Chl a, Chl b, and Chl a+b contents decreased with elevated dose of γ-rays, while increasing carotenoid content indicated that buckwheat was capable of adjusting to the radiation damage. Decrease in net photosynthetic rate was the result of both stomatal and non-stomatal limitations. Fluorescence parameters, such as F0, Fm, Fv/Fm, Fv/F0, ΦPS2, electron transport rate, and photochemical quenching declined significantly (p<0.01) as compared with control due to photoinhibition, while non-photochemical quenching increased to enhance thermal dissipation. Lower parameters implied that leaf tissue was damaged significantly by high dose of γ-radiation and therefore leaf senescence was accelerated. and C. F. Jia, A. L. Li.
The influence of various concentrations of imazapic residues (0-800 μg kg-1) on the growth, chlorophyll content, and photosynthetic characteristics of maize seedlings was studied in a greenhouse pot experiment. Plant height, root length, shoot dry mass, root dry mass, and total dry mass of maize declined with the increase of imazapic residue concentrations. The root/shoot ratio initially decreased and then increased in presence of imazapic, which indicated that the effects of imazapic residues on plant height and root length might differ in maize seedlings. Lowered chlorophyll content and net photosynthetic rate were observed in leaves of maize seedlings in all treatments and indicated a dose-response relationship to imazapic concentrations. Intercellular carbon dioxide concentration, transpiration rate, and stomatal conductance also declined to varying extents, but the chlorophyll a/b ratio increased gradually together with the increase of imazapic residue concentrations. Generally, the maize seedlings were negatively affected by the imazapic residues in soil. Response of root length and biomass to imazapic residues could be the important index for maize variety selection., W. C. Su, L. L. Sun, R. H. Wu, Y. H. Ma, H. L. Wang, H. L. Xu, Z. L. Yan, C. T. Lu., and Obsahuje bibliografii
Lowering irradiance can delay the flower stalk, i.e., spike development, in order to schedule flowering time of Phalaenopsis; however, the effect on photosynthetic performance and spiking inhibition remains poorly understood. We compared light and shade treatments of Phalaenopsis aphrodite subsp. formosana in order to determine how limiting light affects day-night changes in the photosynthetic capacity of leaves and the carbon pool of leaves and stems resulting in delayed spiking. The low irradiance treatment [20 μmol(photon) m-2 s-1] for six weeks did not affect potential functions of photosynthetic apparatus estimated by chlorophyll a fluorescence analysis, but it significantly reduced the net CO2 uptake and O2 evolution rates, carbohydrate and organic acid concentrations, and amplitudes of CAM activity in new and fully expanded leaves of Phalaenopsis and delayed the spiking compared with the control kept at 150 μmol(photon) m-2 s-1. The shortened stem contained a remarkably high sucrose concentration, accounting for more than 80% of total soluble sugars for both treatments throughout the day. Moreover, the sucrose concentration was unaffected by the lowering of irradiance. The relationship between the sucrose content and spiking seemed to be loose; the major factor(s) for spiking in Phalaenopsis remained to be ascertained as the flower stalk bud is attached to the shortened stem., Y.-C. Liu, C.-H. Liu, Y.-C. Lin, C.-H. Lu, W.-H. Chen, H.-L. Wang., and Obsahuje seznam literatury