Control of the Light Saturation Point for Photosynthesis in Tomato

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.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.726-731.4274 ◽

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.

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

PLoS ONE ◽

10.1371/journal.pone.0261683 ◽

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.

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

HortScience ◽

10.21273/hortsci.43.2.314 ◽

2008 ◽

Vol 43 (2) ◽

pp. 314-319 ◽

Cited By ~ 1

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.

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

HortTechnology ◽

10.21273/horttech04442-19 ◽

2019 ◽

Vol 29 (6) ◽

pp. 880-888 ◽

Cited By ~ 1

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.

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

Bangladesh Journal of Botany ◽

10.3329/bjb.v48i3.47912 ◽

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.

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Differential Effects of Lichens versus Liverworts Epiphylls on Host Leaf Traits in the Tropical Montane Rainforest, Hainan Island, China

The Scientific World JOURNAL ◽

10.1155/2014/681369 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10

Author(s):

Lingyan Zhou ◽

Fude Liu ◽

Wenjie Yang ◽

Hong Liu ◽

Hongbo Shao ◽

...

Keyword(s):

Tropical Forests ◽

Host Plants ◽

Leaf Surface ◽

Hainan Island ◽

Leaf Traits ◽

Leaf Water Content ◽

Negative Effects ◽

Saturation Point ◽

Chl A ◽

Light Saturation Point

Epiphylls widely colonize vascular leaves in moist tropical forests. Understanding the effects of epiphylls on leaf traits of host plants is critical for understanding ecological function of epiphylls. A study was conducted in a rain forest to investigate leaf traits of the host plantsPhotinia prunifoliacolonized with epiphyllous liverworts and foliicolous lichens as well as those of uncolonized leaves. Our results found that the colonization of lichens significantly decreased leaf water content (LWC), chlorophyll (Chl) a and a + b content, and Chl a/b ofP. prunifoliabut increased Chl b content, while that of liverworts did not affect them as a whole. The variations of net photosynthetic rates(Pn)among host leaves colonized with different coverage of lichens before or after removal treatment (a treatment to remove epiphylls from leaf surface) were greater than that colonized with liverworts. The full cover of lichens induced an increase of light compensation point (LCP) by 21% and a decrease of light saturation point (LSP) by 54% for their host leaves, whereas that of liverworts displayed contrary effects. Compared with the colonization of liverworts, lichens exhibited more negative effects on the leaf traits ofP. prunifoliain different stages of colonization. The results suggest that the responses of host leaf traits to epiphylls are affected by the epiphyllous groups and coverage, which are also crucial factors in assessing ecofunctions of epiphylls in tropical forests.

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The in vitro banana-leaf-fragment technique preserves the photosynthetic apparatus

International Journal of Current Research in Biosciences and Plant Biology ◽

10.20546/ijcrbp.2021.804.001 ◽

2021 ◽

Vol 8 (4) ◽

pp. 1-10

Author(s):

Edilia De la Rosa-Manzano ◽

Manuel Jesús Cach-Pérez ◽

Cecilia Mónica Rodríguez-García ◽

Leticia Peraza-Echeverría ◽

José Luis Andrade ◽

...

Keyword(s):

Culture Medium ◽

Stomatal Density ◽

Photosynthetic Apparatus ◽

Carbon Dioxide Exchange ◽

Saturation Point ◽

Leaf Fragment ◽

Plant Pathogen Interactions ◽

Banana Leaf ◽

Light Saturation Point

In vitro studies of plant-pathogen interactions using leaf-fragments remains controversial compared to those studies under field conditions. The leaf-fragments technique, which predominantly uses benzimidazole in the culture medium to retard senescence, has been reported as reliable, fast, and inexpensive for analysis of aggressiveness and resistance in the Mycosphaerella fijiensis-Musa spp. interaction. However, no data have been published verifying whether in vitro banana leaf fragments maintain photosynthetic activity, which is a requirement for studying this interaction. In this study, maximum quantum efficiency of photosystem II, electron transport rate, transpiration, carbon dioxide exchange, light saturation point, and stomatal density were evaluated in in vitro leaf fragments of the Grand Nain banana genotype. Furthermore, the same parameters were also attained for leaves from plants in the field (during two seasons) and greenhouse conditions. The photosynthetic yield was constant during the experiment in leaf fragments with benzimidazole, and the photosynthetic rates on day 30 were similar throughout the whole experiment. This study supports that the banana-leaf-fragment technique as such protects the photosynthetic apparatus and then is suitable for studies on interactions such as that of M. fijiensis-Musa acuminata.

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PHOTOSYNTHETIC POTENTIAL OF SPUR LEAVES WITHIN AN APPLE CANOPY

HortScience ◽

10.21273/hortsci.25.9.1102 ◽

1990 ◽

Vol 25 (9) ◽

pp. 1102G-1102

Author(s):

Richard J. Campbell ◽

Richard Marini

Keyword(s):

Linear Regression ◽

Light Saturation ◽

Saturation Point ◽

Indicator Variables ◽

Peripheral Position ◽

Non Linear ◽

Photosynthetic Potential ◽

Light Saturation Curves

Light saturation curves were developed for detached, non-fruiting `Stayman' and `Delicious' spur leaves from interior, middle, and peripheral canopy positions throughout the season in 1989 and 1990, respectively. Be inning at bloom, measurements were made every 2 weeks for the first 8 weeks, and monthly thereafter. SLW was calculated simultaneously with photosynthetic measurements. MacArthur-Wilson saturation equations were used with non-linear regression to fit the saturation curves and SLW data, and curves were compared using indicator variables. Even at bloom, saturation curves and SLW differed among positions. The peripheral position bad a greater saturation point and equilibrium rate throughout the season, and the interior and middle positions were equivalent by about 6 weeks after bloom.

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The Effect of KHCO3 on Photosynthesis of Eggplant Seedlings

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.1129 ◽

2013 ◽

Vol 634-638 ◽

pp. 1129-1134 ◽

Cited By ~ 1

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.

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