Tomato seeds exposed to space conditions for nearly six years on board the Long Duration Exposure Facility (LDEF) satellite were subsequently germinated and the resultant seedlings grown on earth under controlled conditions for analysis. Photosynthesis, biomass, and water relations were compared between mature plants grown from earth-based control seeds and space-exposed seeds under both well-watered and drought-stressed conditions. No consistent significant differences in photosynthesis and water relations were observed in the two sets of plants at any level of drought stress. Fruit production, however, though limited and variable, was significantly greater in plants grown from space-exposed seeds than in plants grown from earth-based seeds. Overall, exposure of seeds to space had only minor effects on the physiology and growth of plants grown from such seed. and M. S. Marmor, C. E. Martin.
The frequent occurrence of monsoon winds usually leads to the formation of inverted soybean leaves. However, the effect of leaf inversion on photosynthetic capacity remains unclear. The responses of leaf anatomical traits, chlorophyll fluorescence induction kinetics parameters, photosynthetic capacity, and nonstructural carbohydrates of fully expanded leaves to inversion of leaves in two soybean cultivars were studied. Leaf inversion decreased the stomatal size and thickness of developed leaves. The net photosynthetic rate was significantly reduced under leaf inversion, which resulted from reduced excitation energy trapping and electron transport of PSII reaction center. Leaf inversion increased leaf temperature 10 d after leaf inversion but reduced the instantaneous water-use efficiency compared to normally oriented leaves. Due to the decreased light-saturated net photosynthetic rate, the soluble sugars of light-sensitive cultivar decreased significantly. In summary, leaf inversion deactivated the PSⅡ reaction centers, reduced photosynthesis and nonstructural carbohydrates in upper canopy soybean leaves.
Tartary buckwheat (Fagopyrum tataricum Gaertn) has been praised as one of green foods for humans in the 21st century. Effects of fertilization on leaf photosynthetic characteristics and grain yield of tartary buckwheat has not been yet reported in detail. Our experiment was set as a split-plot factorial. The main plots and subplots were designed by fertilizer ratio and rate as: NPK 1:1:1 (A1), NPK 1:4:2 (A2), NPK 1:2:3 (A3), and 300 (B1), 450 (B2), and 600 (B3) kg (NPK) ha-1. Our results showed that the grain yield was significantly and positively correlated with the net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), PAR, stomatal limitation value (Ls), chlorophyll content (SPAD value), and leaf area index (LAI), while significantly and negatively correlated with intercellular CO2 concentration (Ci) and water-use efficiency (WUE). The grain yield, PN, gs, E, PAR, Ls, SPAD, and LAI increased and then decreased with enhanced fertilization, and their maximum values appeared in the A2B2 treatment. The Ci and WUE decreased and then increased with enhanced fertilization, and their minimum values appeared in the A2B2 treatment. Our results suggested that fertilization had significant effects on the leaf photosynthetic capacity and grain yield of tartary buckwheat
Yunqiao1, and the best fertilization strategy was 450 kg ha-1 with NPK 1:4:2., C. Wang, H. Z. She, X. B. Liu, D. Hu, R. W. Ruan, M. B. Shao, L. Y. Zhang, L. B. Zhou, G. B. Zhang, D. Q. Wu, Z. L. Yi., and Obsahuje bibliografii
We carried out a field experiment in order to study effects of fertilization in juvenile plants of three coffee (Coffea arabica) cultivars in Yunnan, SW China. Fertilization treatments included a control without fertilizer (CK), combinations of three NPK fertilization rates [high fertilization (FH), medium fertilization (FM), and low fertilization (FL) with 135, 90, and 45 g per plant per year, respectively], and at two N:P2O5:K2O ratios (R1, 1:0.5:0.8; R2, 1:0.8:0.5). The growth in juvenile plants was not altered by fertilization, with two clear growth peaks being observed in both the height and stem growth rates (RGRs) throughout a year. Both FM and FH resulted in significantly higher RGRs in both height and stem diameter compared to FL and CK in all three cultivars. At the same fertilization rate, the leaf area, branch number, longest branch length, internode number, and biomass of R2 were higher than those of R1, and P significantly affected the root biomass and root to shoot ratio. Compared to the FL treatment, both FM and FH treatments resulted in higher net photosynthetic rates and stomatal conductance across seasons, and in higher intrinsic water-use efficiency during the dry season and at the middle of the wet season. Photosynthetic nitrogen-use efficiency at R2 was higher than that at R1, but no significant differences were observed between the different fertilization rates. Among the three coffee cultivars, Caturra exhibited the highest height, stem diameter, longest branch length, and internode number. Our results indicated that the optimal N:P2O5:K2O ratio was 1:0.8:0.5 for the juvenile growth of coffee plants. Both FM and FH could help optimize the growth and photosynthetic rate of coffee plants, but FM is suitable for the ecological friendly agriculture and economic sustainability at coffee plantations., Z. X. Zhang, Z. Q. Cai, G. Z. Liu, H. Wang, L. Huang, C. T. Cai., and Obsahuje bibliografii
Fibres, cables, wires and fibres can play an important role in design of many machines. One of the most interesting applications is replacement of chosen rigid elements of a manipulator or a mechanism by cables. The main advantage of this design is the achievement of a lower moving inertia, which leads to a higher mechanism speed, and lower production costs. An inverted pendulum attached and driven by two fibres serves as a typical testing system for the investigation of the fibres properties influence of the system dynamic response. Motion of the pendulum of this nonlinear system is investigated using the alaska simulation tool and an in-house program created in the MATLAB system. Since mass of fibres can influence employed types of fibre models, chosen dynamic quantities (e.g. pendulum angle, vibration amplitude etc.), are investigated in dependence on the excitation frequency for various fibres weights. and Obsahuje seznam literatury
The evolution of different foraging strategies, corresponding echolocation signals and adaptations of wing morphologies allowed niche differentiation and sympatric foraging habitat use of bat species. We investigated how different habitat selection transferred into sympatric species groups (“bat communities”). The occurrence of bat species at different transects and landscape structures of five sites of a low mountain range forest in the south west of Germany was determined. Species were present at transects in the following descending order: Pipistrellus pipistrellus > Myotis myotis > Nyctalus leisleri > N. noctula > Myotis daubentonii > Eptesicus serotinus > Plecotus austriacus. We analyzed patterns of habitat use and evaluated differences in community structure. Landscape structures (patch types) influenced more than geographical location of sites within the landscape the bat community structure. Bat communities at individual forest sites disaggregated into different smaller species groups of one to at least eight species at different landscape structures. The results confirm previously proposed models of foraging habitat use of bats. Species groups clustered in correlation with the landscape structures “open area” (clearance or grassland), “closed or open canopy forest”, and “still water”. The highest bat diversity foraged predominantly at open canopy forest, which may fulfil best the requirements of several distinct functional groups (guilds) of bats.
Responses of baldcypress (Taxodium distichum) seedlings to soil moisture were studied to test the hypothesis that flooding may lead to seedling's higher susceptibility to drought. Treatments included a well-watered but drained control (C), continuously flooded (CF), control followed by drought (CD), and flooded followed by drought (FD). Gas exchange values revealed no significant effects on net photosynthetic rate (PN) in response to flooding. In contrast, after the onset of drought, PN was significantly reduced in CD and FD plants. Significant growth reductions under mild drought conditions indicated that baldcypress seedlings were drought sensitive. However, comparison of gas exchange rates and growth responses between CD and FD plants indicated that prior flooding had no detectable effect on subsequent sensitivity of baldcypress to drought. These findings explain baldcypress persistence in wetland habitats characterized by periodic flooding and mild drought. and J. M. Elcan, S. R. Pezeshki.
Greenhouse experiments showed that the preemergence herbicide fluchloralin ušed at recommended level inhibited the activities of nitiite reductase, net photosynthetic rate and DCPIP photoreduction but did not cause appreciable reduction in nitráte reductase activity. Prolonged treatment of groundnut cv. TMV-2 with fluchloralin resulted in accumulation of nitrite in leaves whereas statistically significant changes were not found in leaf crude protein and chlorophyll contents and growth of plants during different stages of growth.
The effects of exogenous sodium nitroprusside (SNP), as nitric oxide donor, and spermidine (Spd) on growth and photosynthetic characteristics of Bakraii seedlings (Citrus reticulata x Citrus limetta) were studied under NaCl stress. In citrus plants, SNP- and Spd-induced growth improvement was found to be associated with reduced electrolyte leakage, malondialdehyde, hydrogen peroxide content, and leaf Na+ and Cl- concentration. However, we found increased leaf Ca2+, Mg2+, and K+ concentrations, relative water content, chlorophyll fluorescence parameters, antioxidant enzyme activities, such as ascorbate peroxidase, catalase, superoxide dismutase and peroxidase, as well as higher photosynthetic rate, intercellular CO2 concentration, stomatal conductance, and transpiration rate under saline regime. Foliar application of SNP and Spd alone mitigated the adverse effect of salinity, while the combined application proved to be even more effective., D. Khoshbakht, M. R. Asghari, M. Haghighi., and Obsahuje bibliografii
The objective of this study was to investigate the effect of elevated (550 ± 17 μmol mol-1) CO2 concentration ([CO2]) on leaf ultrastructure, leaf photosynthesis and seed yield of two soybean cultivars [Glycine max (L.) Merr. cv. Zhonghuang 13 and cv. Zhonghuang 35] at the Free-Air Carbon dioxide Enrichment (FACE) experimental facility in North China. Photosynthetic acclimation occurred in soybean plants exposed to long-term elevated [CO2] and varied with cultivars and developmental stages. Photosynthetic acclimation occurred at the beginning bloom (R1) stage for both cultivars, but at the beginning seed (R5) stage only for Zhonghuang 13. No photosynthetic acclimation occurred at the beginning pod (R3) stage for either cultivar. Elevated [CO2] increased the number and size of starch grains in chloroplasts of the two cultivars. Soybean leaf senescence was accelerated under elevated [CO2], determined by unclear chloroplast membrane and blurred grana layer at the beginning bloom (R1) stage. The different photosynthesis response to elevated [CO2] between cultivars at the beginning seed (R5) contributed to the yield difference under elevated [CO2]. Elevated [CO2] significantly increased the yield of Zhonghuang 35 by 26% with the increased pod number of 31%, but not for Zhonghuang 13 without changes of pod number. We conclude that the occurrence of photosynthetic acclimation at the beginning seed (R5) stage for Zhonghuang 13 restricted the development of extra C sink under elevated [CO2], thereby limiting the response to elevated [CO2] for the seed yield of this cultivar., X. Y. Hao ... [et al.]., and Obsahuje bibliografii