Effects of photosynthetic models on the calculation results of photosynthetic response parameters in young Larix principis-rupprechtii Mayr. plantation

Accurately predicting the crown photosynthesis of trees is necessary for better understanding the C circle in terrestrial ecosystem. However, modeling crown for individual tree is still challenging with the complex crown structure and changeable environmental conditions. This study was conducted to explore model in modeling the photosynthesis light response curve of the tree crown of young Larix principis-rupprechtii Mayr. Plantation. The rectangular hyperbolic model (RHM), non-rectangular hyperbolic model (NRHM), exponential model (EM) and modified rectangular hyperbolic model (MRHM) were used to model the photosynthetic light response curves. The fitting accuracy of these models was tested by comparing determinants coefficients (R2), mean square errors (MSE) and Akaike information criterion (AIC). The results showed that the mean value of R2 of MRHM (R2 = 0.9687) was the highest, whereas MSE value (MSE = 0.0748) and AIC value (AIC = -39.21) were the lowest. The order of fitting accuracy of the four models for Pn-PAR response curve was as follows: MRHM > EM > NRHM > RHM. In addition, the light saturation point (LSP) obtained by MRHM was slightly lower than the observed values, whereas the maximum net photosynthetic rates (Pmax) modeled by the four models were close to the measured values. Therefore, MRHM was superior to other three models in describing the photosynthetic response curve, the accurate values were that the quantum efficiency (α), maximum net photosynthetic rate (Pmax), light saturation point (LSP), light compensation point (LCP) and respiration rate (Rd) were 0.06, 6.06 μmol·m-2s-1, 802.68 μmol·m-2s-1, 10.76 μmol·m-2s-1 and 0.60 μmol·m-2s-1. Moreover, the photosynthetic response parameters values among different layers were also significant. Our findings have critical implications for parameter calibration of photosynthetic models and thus robust prediction of photosynthetic response in forests.

Influence of anthropogenic impact of vehicles on roadside forest plantations

The article presents studies of the growth and development of forest stands along highways as a result of man-made impacts from road transport emissions. The obtained mathematical model describing the dynamics of the growth of the biomass of stands of various bonities of roadside stands during the period of light saturation is presented. In this regard, the obtained mathematical model describing the dynamics of the growth of the biomass of stands of various bonitets of roadside forest stands during the period of light saturation is presented. The use of the bonus in research to characterize the growth rate of forest roadside plantings depending on the distance to highways and the density of traffic flows on them allows us to characterize the amount of toxic pollutants entering forests. This allows us to assess the process of expanding the environmentally unfavorable zone along the highway. The article presents the possibility of calculating the concentration of pollutants, based on the model of turbulent diffusion, reduced, after some assumption, to the model of Gaussian distribution in atmospheric air. The dependence on the calculation of the intensity of emissions of pollutants, taking into account the composition of the traffic flow, is given.

Fitomonitorizarea intensităţii fotosintezei, respiraţiei şi transpiraţiei la pomii de păr

The paper presents the results regarding the phytomonitoring of physiological processes in pear trees. The modern RTM-48A phytomonitor was used, which allowed the measurement of indices in the form of a film-phytodiagram that allows the diagnosis of the properties of genotype and physiological con-dition of plants. The light saturation curve for photosynthesis in pear plants was determined as a result of the evaluation of the intensity of photosynthesis, respiration, transpiration, stomata conductivity as a func-tion of temperature, humidity and CO2 content in the air. The minimum value of light at which the photo-synthesis process is initiated has been established. As the light intensity increases (1/3 of the total light) the intensity of photosynthesis increases after the essential optimization of the process has taken place.

Isolation, growth, and nitrogen fixation rates of the Hemiaulus-Richelia (diatom-cyanobacterium) symbiosis in culture

Nitrogen fixers (diazotrophs) are often an important nitrogen source to phytoplankton nutrient budgets in N-limited marine environments. Diazotrophic symbioses between cyanobacteria and diatoms can dominate nitrogen-fixation regionally, particularly in major river plumes and in open ocean mesoscale blooms. This study reports the successful isolation and growth in monocultures of multiple strains of a diatom-cyanobacteria symbiosis from the Gulf of Mexico using a modified artificial seawater medium. We document the influence of light and nutrients on nitrogen fixation and growth rates of the host diatom Hemiaulus hauckii Grunow together with its diazotrophic endosymbiont Richelia intracellularis Schmidt, as well as less complete results on the Hemiaulus membranaceus-R. intracellularis symbiosis. The symbioses rates reported here are for the joint diatom-cyanobacteria unit. Symbiont diazotrophy was sufficient to support both the host diatom and cyanobacteria symbionts, and the entire symbiosis replicated and grew without added nitrogen. Maximum growth rates of multiple strains of H. hauckii symbioses in N-free medium with N2 as the sole N source were 0.74–0.93 div d−1. Growth rates followed light saturation kinetics in H. hauckii symbioses with a growth compensation light intensity (EC) of 7–16 µmol m−2s−1and saturation light level (EK) of 84–110 µmol m−2s−1. Nitrogen fixation rates by the symbiont while within the host followed a diel pattern where rates increased from near-zero in the scotophase to a maximum 4–6 h into the photophase. At the onset of the scotophase, nitrogen-fixation rates declined over several hours to near-zero values. Nitrogen fixation also exhibited light saturation kinetics. Maximum N2 fixation rates (84 fmol N2 heterocyst−1h−1) in low light adapted cultures (50 µmol m−2s−1) were approximately 40–50% of rates (144–154 fmol N2 heterocyst−1h−1) in high light (150 and 200 µmol m−2s−1) adapted cultures. Maximum laboratory N2 fixation rates were ~6 to 8-fold higher than literature-derived field rates of the H. hauckii symbiosis. In contrast to published results on the Rhizosolenia-Richelia symbiosis, the H. hauckii symbiosis did not use nitrate when added, although ammonium was consumed by the H. hauckii symbiosis. Symbiont-free host cell cultures could not be established; however, a symbiont-free H. hauckii strain was isolated directly from the field and grown on a nitrate-based medium that would not support DDA growth. Our observations together with literature reports raise the possibility that the asymbiotic H. hauckii are lines distinct from an obligately symbiotic H. hauckii line. While brief descriptions of successful culture isolation have been published, this report provides the first detailed description of the approaches, handling, and methodologies used for successful culture of this marine symbiosis. These techniques should permit a more widespread laboratory availability of these important marine symbioses.

On Methodology for Designing Architectural Lighting of Production Site Interior Part 111: Results and Conclusions

This is the final, third part, on the presentation of Chapter 4 and the results of the Vladimir Voronov thesis [1], successfully defended at the Moscow Architectural Institute in 1985 and devoted to the author’s method of designing architectural lighting for industrial interiors with three main upper lantern types of natural daylight and artificial lighting. The method was developed on the basis of longterm analytical calculations and numerous experiments conducted according to all the laws of statistics in natural conditions and in the camera “Mirror-type artificial sky” created by the author using planar and volumetric (on mock-ups) light modelling with careful measurement of lighting parameters characterizing various states, qualities and options for luminance composition, light saturation of the interior space, contrast of lighting, etc. The conclusions of the dissertation give a general picture of the research work performed, the main meaning of which is the belief that the design of lighting in industrial (and in any other) interiors is not limited to providing elementary normalized lighting parameters, but is a complex, sophisticated, and creative task of architectural design where the light – natural and artificial – is the main “actor”, providing functional and aesthetic qualities to the interior.

Quantitative relationship between solar radiation intensity and average daily value of photosynthesis light saturation for phytoplankton in the deep-water area of the Black Sea

According to data obtained during expeditions in the Black Sea (1987–1993), linear relationship between the light flux density incident on the sea surface (E0) and the starting point of photosynthesis light saturation (En opt) is revealed. For calculations, measurements of phytoplankton photosynthesis rate obtained by the radiocarbon method were used. The equation of the relationship between the values reported is presented for the first time for the Black Sea. En opt is the average daily, optimal value of photosynthesis light saturation. The parameters of photosynthesis – light curve, determined in short-period exposures under constant illumination, differ from the parameters obtained in long-term experiments under conditions of variable illumination. This is due to different effects of the intensity and dose on the phytoplankton photosynthesis rate. The values of photosynthetic parameters for a certain time are integrated into a single value which is the optimum for the entire period observed. The approximation of daily data integrated is carried out both separately for seasons and in general for the period of 1987–1993. Using statistical processing of data of average daily values of the intensity of solar radiation incident on the sea surface, slope of the photosynthesis – light curve, and maximum photosynthesis rate, the approximation is determined for the functional dependence of En opt on E0. The equation is applicable in the range of light intensity 3 to 75 mol quanta·m−2·day−1. It describes with high reliability a change of average daily value of photosynthesis light saturation in the Black Sea during different seasons of the year. The equation includes a parameter easily accessible for measurement. It can be used in analysis of physiological characteristics of phytoplankton and calculation of integrated phytoplankton productivity in euphotic layer with using both satellite and expedition data.

Growth and Photosynthetic Capacity of Basil Grown for Indoor Gardening under Constant or Increasing Daily Light Integrals

In the quest to identify minimum daily light integrals (DLIs) that can sustain indoor gardening, we evaluated DLIs less than the recommended ranges for commercial production of basil (Ocimum basilicum). Experiments were conducted for 8 weeks to evaluate the effect of providing a constant vs. an increasing DLI over time (DLIInc) on growth and photosynthetic capacity of green (‘Genovese Compact’) and purple (‘Red Rubin’) basil grown hydroponically under a constant ambient temperature of 21 °C. Plants were grown under a 14 h·d–1 photoperiod and were subjected to the following DLI treatments: 4 (DLI4), 6 (DLI6), 8 (DLI8), or 10 (DLI10) mol·m–2·d‒1 (80, 119, 159, and 197 µmol·m‒2·s‒1, respectively); DLIInc was used as a fifth treatment and was achieved by transitioning hydroponic systems systematically to treatments with greater DLIs every 2 weeks. In general, regardless of cultivar, leaf area, leaf number, and overall growth [shoot fresh weight (SFW) and shoot dry weight (SDW)] were similar for plants grown under DLIInc to DLI4 and DLI6 during weeks 2, 4, and 6. However, plants grown under DLIInc produced the same leaf area as those grown under DLI10 at week 8. Nonetheless, across weeks, growth was significantly less under DLIInc compared with DLI10, but similar to that produced by DLI8 at week 8. Photosynthetic responses were significant only at week 8, for which leaves of plants grown under DLI8, DLI10, and DLIInc had 15% to 25% greater maximum gross carbon dioxide (CO2) assimilation (Amax) than plants grown under DLI4. The light saturation point of photosynthesis was unaffected by DLI, but showed a general increasing trend with greater DLIs. Overall, our results suggest that providing a constantly high DLI results in greater growth and yield than increasing the DLI over time. In addition, we found that changes in Amax and the light saturation point are not good indicators of the capacity of whole plants to make use of the available light for photosynthesis and growth. Instead, morphological and developmental traits regulated by DLI during the initial stages of production are most likely responsible for the growth responses measured in our study.

Effects of light stress and light recovery on two maize (Zea mays L.) cultivars

The responses of a density-tolerant (ZD909) and a density-intolerant (DY405) maize cultivar to weak light stress and light recovery were compared. Photosynthetic characteristics and chlorophyll fluorescence parameters were analyzed under three light treatments: natural light (control), 44% shading and 66% shading. The light-saturation point and light-compensation point of both the maize cultivars decreased, whereas the apparent quantum efficiency increased during the shade period and the decreasing degree of light-saturation point and light-compensation point and the increasing degree of apparent quantum efficiency of the ZD909 were both higher than those of DY405. The weak light stress in the spike stage had a greater influence on the photosynthetic characteristics and chlorophyll fluorescence parameters of DY405, which indicated DY405 was less able to adapt to a weak light environment compared with ZD909.

Growth and Needle Properties of Young Pinus koraiensis Sieb. et Zucc. Trees across an Elevational Gradient

A better understanding of the response of plant growth to elevational gradients may shed light on how plants respond to environmental variation and on the physiological mechanisms underlying these responses. This study analyzed whole plant growth and physiological and morphological properties of needles in young Pinus koraiensis Sieb. et Zucc. trees at thirteen points along an elevational gradient ranging from 750 to 1350 m above sea level (a.s.l.) at the end of a growing season on Changbai Mountain in northeastern China. Sampling and analyses indicated the following; (1) many needle properties of P. koraiensis varied with forest type along the elevational gradient though some needle properties (e.g., intrinsic water use efficiency, concentration of chlorophyll, and leaf mass per area) did not change with elevation and forest types; (2) growth was significantly influenced by both forest type and elevation and growth of saplings in P. koraiensis and mixed broadleaved forests was greater than that in evergreen forests and increased with elevation in both forest types; (3) in P. koraiensis and mixed broadleaved forests, there were significant correlations between growth properties and light saturation point, leaf water potential, mean within-crown humidity, annual precipitation, cumulative temperature (≥5 ∘ C), within-crown air temperature, and atmospheric pressure; while in evergreen forests, the leaf C, leaf P content, net rate of light saturation in photosynthesis, water content of soil, within-crown humidity, annual precipitation, cumulative temperature (≥5 ∘ C), within-crown air temperature, and total soil P content displayed a significant relationship with plant growth. These results may help illuminate how P. koraiensis responds to environmental variation and evaluate the adaptive potential of Pinus koraiensis to climate change. Data presented here could also contribute to the more accurate estimation of carbon stocks in this area and to refinement of a plant trait database.