scholarly journals Photosynthetic Characteristics of Four Wild Dendrobium Species in China

HortScience ◽  
2014 ◽  
Vol 49 (8) ◽  
pp. 1023-1027
Author(s):  
Gang-Yi Wu ◽  
Jun-Ai Hui ◽  
Zai-Hua Wang ◽  
Jie Li ◽  
Qing-Sheng Ye
Keyword(s):  
Glycolate Oxidase ◽  
Photosynthetic Pathway ◽  
Light Saturation ◽  
Saturation Point ◽  
Apparent Quantum Yield ◽  
Bisphosphate Carboxylase ◽  
Photosynthetic Physiology ◽  
Light Saturation Point ◽  
Second Peak ◽  
Dendrobium Densiflorum

Photosynthetic physiology of Dendrobium nobile, Dendrobium pendulum, Dendrobium chrysotoxum, and Dendrobium densiflorum was studied. A bimodal diurnal variation of the net photosynthetic rate (Pn) was observed in the four Dendrobium species with the first peak [5.09 to 6.06 μmol (CO2) per m−2·s−1] ≈1100 hr and the second peak [3.83 to 4.58 μmol (CO2) per m−2·s−1] at 1500 hr. No CO2 fixation was observed at night. For all four Dendrobium species, the light compensation point (LCP) was 5 to 10 μmol·m−2·s−1, light saturation point (LSP) ranged from 800 to 1000 μmol·m−2·s−1, apparent quantum yield (AQY) was 0.02, and CO2 compensation points (CCP) and saturation point (CSP) were 60 to 85 μmol·mol−1 and 800 to 1000 μmol·mol−1, respectively. Carboxylation efficiency (CE) values ranged from 0.011 to 0.020. The optimum temperature for photosynthesis was between 26 and 30 °C. The measurement of Pn seasonal variation indicated that July to August had the higher Pn for Dendrobium species. Additionally, the chlorophyll a/b (Chl a/b) ratios of the leaves were 2.77 to 2.89. Measurement of key enzymes in the photosynthetic pathway indicated relatively high Ribulose-1,5-bisphosphate carboxylase (RuBPCase) and glycolate oxidase (GO) activities but very low phosphoenolpyruvate carboxylase (PEPCase) activities. It suggested that these four Dendrobium species are typical semishade C3 plants.

The Photosynthetic Characteristics of Moso Bamboo (Phyllostachys pubescens) for Different Canopy Leaves

2013 ◽  
Vol 726-731 ◽  
pp. 4274-4279
Author(s):  
Yong Hui Cao ◽  
Ben Zhi Zhou ◽  
Xiao Ming Wang ◽  
Gang Wang
Keyword(s):  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Lower Layer ◽  
Middle Layer ◽  
B Value ◽  
Phyllostachys Pubescens ◽  
Light Saturation ◽  
Saturation Point ◽  
Low Light ◽  
Light Saturation Point

The carbon sequestration ability of different ages of Phyllostachys pubescens was analyzed at three canopy layers with a LI-6400 portable photosynthesis system. Under different photosynthetically active radiation (PAR), the net photosynthetic rate (Pn) of upper and middle layers of 3-year old bamboo were significantly higher than that of lower layer. When the light was greater than 800 umol·m-2·s-1, the Pn of bamboo in middle layer was in the order of 3-year-old > 4-year- old >2-year-old >7-year-old bamboo. When the light was greater than 500 umol·m-2·s-1, Pn of lower layer was in the order of 3-year old > 4-year old >2-year old, while in the order of 3-year-old > 2-year -old >4-year-old bamboo during the low light range (PAR<200 umol·m-2·s-1).The chlorophyll a/b value, maximum net photosynthetic rate, light compensation point and light saturation point values change were reduced gradually with the decrease of canopy height.

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

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261683
Author(s):  
Xuemei Ma ◽  
Qiang Liu ◽  
Zhidong Zhang ◽  
Zewen Zhang ◽  
Zeyu Zhou ◽  
...  
Keyword(s):  
Response Curve ◽  
Light Response ◽  
Hyperbolic Model ◽  
Photosynthetic Response ◽  
Light Saturation ◽  
Saturation Point ◽  
Individual Tree ◽  
Mean Square Errors ◽  
Light Saturation Point ◽  
Fitting Accuracy

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.

scholarly journals Photosynthesis of Birch Genotypes (Betula L.) Under Varied Irradiance and CO2 Concentration

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 314-319 ◽  
Author(s):  
Mengmeng Gu ◽  
James A. Robbins ◽  
Curt R. Rom ◽  
Hyun-Sug Choi
Keyword(s):  
Water Deficit ◽  
Co2 Concentration ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Water Deficit Stress ◽  
Growth Enhancement ◽  
Light Saturation ◽  
Saturation Point ◽  
Light Saturation Point

Net CO2 assimilation (A) of four birch genotypes (Betula nigra L. ‘Cully’, B. papyrifera Marsh., B. alleghaniensis Britton, and B. davurica Pall.) was studied under varied photosynthetic photon flux density (PPFD) and CO2 concentrations (CO2) as indicators to study their shade tolerance and potential for growth enhancement using CO2 enrichment. Effect of water-deficit stress on assimilation under varied PPFD and (CO2) was also investigated for B. papyrifera. The light saturation point at 350 ppm (CO2) for the four genotypes varied from 743 to 1576 μmol·m−2·s−1 photon, and the CO2 saturation point at 1300 μmol·m−2·s−1 photon varied from 767 to 1251 ppm. Light-saturated assimilation ranged from 10.4 μmol·m−2·s−1 in B. alleghaniensis to 13.1 μmol·m−2·s−1 in B. davurica. CO2-saturated A ranged from 18.8 μmol·m−2·s−1 in B. nigra ‘Cully’ to 33.3 μmol·m−2·s−1 in B. davurica. Water-deficit stress significantly reduced the light saturation point to 366 μmol photon m−2·s−1 but increased the CO2 saturation point in B. papyrifera. Carboxylation efficiency was reduced 46% and quantum efficiency was reduced 30% by water-deficit stress in B. papyrifera.

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

2019 ◽  
Vol 29 (6) ◽  
pp. 880-888 ◽  
Author(s):  
Elisa Solis-Toapanta ◽  
Celina Gómez
Keyword(s):  
Leaf Area ◽  
Photosynthetic Capacity ◽  
Dry Weight ◽  
Growth And Yield ◽  
Growth Responses ◽  
Light Saturation ◽  
Saturation Point ◽  
Shoot Dry Weight ◽  
Light Saturation Point ◽  
Over Time

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.

The Effect of KHCO3 on Photosynthesis of Eggplant Seedlings

2013 ◽  
Vol 634-638 ◽  
pp. 1129-1134 ◽  
Author(s):  
Ying Chang Li ◽  
Jian Jun Hao
Keyword(s):  
Stomatal Conductance ◽  
Photosynthetic Rate ◽  
Impact Factors ◽  
C3 Plants ◽  
Transport Activity ◽  
Saturation Point ◽  
Rubisco Activity ◽  
Bisphosphate Carboxylase ◽  
Electron Transport Activity ◽  
Light Saturation Point

The low concentration of CO2 in the atmosphere is one of the main factors to restrict photosynthesis of C3 plants. The effect of KHCO3 on photosynthesis of eggplant seedlings was studied in order to improve photosynthesis of C3 plants. The results showed that KHCO3 could significantly enhance the photosynthetic rate of eggplant seedlings. 500mg/L KHCO3 was the most optimal concentration to improve photosynthetic rate of eggplant seedlings. KHCO3 could increase light saturation point, CO2 saturation point, carboxylase efficiency and lower CO2 compensate point of eggplant seedlings. KHCO3 could improve stomatal conductance and electron transport activity. There was phosphoenolpyruvate carboxylase (PEPC) in leaves of eggplant seedlings, but PEPC activity was low. KHCO3 could improve ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity and PEPC activity. From impact factors, HCO3- could enhance photosynthetic rate. K+ could raise stomatal conductance of eggplant seedlings. HCO3- could improve activity of PEPC . Both HCO3- and K+ could increase Rubisco activity.

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

2019 ◽  
Vol 48 (3) ◽  
pp. 513-520
Author(s):  
Hongyu Zhang ◽  
Ping Tian ◽  
Nan Mel ◽  
Pengxiang Sui ◽  
Wenke Zhang ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Quantum Efficiency ◽  
Light Stress ◽  
Light Saturation ◽  
Saturation Point ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Apparent Quantum Efficiency ◽  
Weak Light ◽  
Light Saturation Point

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.

scholarly journals Transcriptome-wide gene expression plasticity in Stipa grandis in response to grazing intensity differences

2020 ◽  
Author(s):  
Zhenhua Dang ◽  
Yuanyuan Jia ◽  
Yunyun Tian ◽  
Jiabin Li ◽  
Yanan Zhang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Metabolic Pathways ◽  
Molecular Mechanisms ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Grazing Intensity ◽  
Glycolate Oxidase ◽  
Bisphosphate Carboxylase ◽  
Grazing Intensities

Organisms have evolved effective and distinct adaptive strategies to survive. Stipa grandis is one of the widespread dominant species on the typical steppe of the Inner Mongolian Plateau, and is regarded as a suitable species for studying the effects of grazing in this region. Although phenotypic (morphological and physiological) variations in S. grandis in response to long-term grazing have been identified, the molecular mechanisms underlying adaptations and plastic responses remain largely unknown. Accordingly, we performed a transcriptomic analysis to investigate changes in gene expression of S. grandis under four different grazing intensities. A total of 2,357 differentially expressed genes (DEGs) were identified among the tested grazing intensities, suggesting long-term grazing resulted in gene expression plasticity that affected diverse biological processes and metabolic pathways in S. grandis. DEGs were identified that indicated modulation of Calvin–Benson cycle and photorespiration metabolic pathways. The key gene´expression profiles encoding various proteins (e.g., Ribulose-1,5-bisphosphate carboxylase/oxygenase, fructose-1,6-bisphosphate aldolase, glycolate oxidase etc.) involved in these pathways suggest that they may synergistically respond to grazing to increase the resilience and stress tolerance of S. grandis. Our findings provide scientific clues for improving grassland use and protection, and identify important questions to address in future transcriptome studies.

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