Light quality (red:far-red ratio): does it affect photosynthetic activity, net CO2 assimilation, and morphology of young white clover leaves?

2000 ◽  
Vol 77 (10) ◽  
pp. 1425-1431 ◽  
Author(s):  
V Heraut-Bron ◽  
C Robin ◽  
C Varlet-Grancher ◽  
D Afif ◽  
A Guckert
Keyword(s):  
Leaf Area ◽  
White Clover ◽  
Leaf Morphology ◽  
Photosynthetic Activity ◽  
Red Light ◽  
Co2 Assimilation ◽  
Assimilation Rate ◽  
Light Emitting ◽  
Net Co2 Assimilation ◽  
R:Fr Ratio

We assessed the effects of red:far-red (R:FR) ratio on net CO2 assimilation, photosynthetic activity, and morphology of young white clover leaves developed under a simulated canopy light environment. Isolated cuttings of Trifolium repens L. were grown in controlled conditions under two irradiances in combination with two R:FR ratios. We used far-red light emitting diodes to reduce the R:FR ratio on leaves that were successively developing on the main stolon and were subject to strong competition for light within a sward. A leaf that developed under a low R:FR ratio had a lower chlorophyll content than the controls. However, this change had no consequences on the net CO2 assimilation rate and on the biomass allocated to shoots. The low R:FR ratio modified the leaf morphology by increasing the leaf area. A leaf that developed in lower irradiance had a lower net CO2 assimilation rate and a greater leaf area and petiole length than leaves that developed in higher irradiance. Therefore, irradiance was the main factor limiting the leaf CO2 assimilation under a canopy. Capture of light by clover leaves was improved by FR light only via modifications of leaf morphology, because there were no significant effects of FR light on photosynthesis.

scholarly journals Salt tolerance and regulation of gas exchange and hormonal homeostasis by auxin-priming in wheat

2013 ◽  
Vol 48 (9) ◽  
pp. 1210-1219 ◽  
Author(s):  
Muhammad Iqbal ◽  
Muhammad Ashraf
Keyword(s):  
Abscisic Acid ◽  
Gas Exchange ◽  
Acid Concentration ◽  
Spring Wheat ◽  
Indoleacetic Acid ◽  
Co2 Assimilation ◽  
Assimilation Rate ◽  
Co2 Assimilation Rate ◽  
Net Co2 Assimilation Rate ◽  
Net Co2 Assimilation

The objective of this work was to assess the regulatory effects of auxin-priming on gas exchange and hormonal homeostasis in spring wheat subjected to saline conditions. Seeds of MH-97 (salt-intolerant) and Inqlab-91 (salt-tolerant) cultivars were subjected to 11 priming treatments (three hormones x three concentrations + two controls) and evaluated under saline (15 dS m-1) and nonsaline (2.84 dS m-1) conditions. The priming treatments consisted of: 5.71, 8.56, and 11.42 × 10-4 mol L-1 indoleacetic acid; 4.92, 7.38, and 9.84 × 10-4 mol L-1 indolebutyric acid; 4.89, 7.34, and 9.79 × 10-4 mol L-1 tryptophan; and a control with hydroprimed seeds. A negative control with nonprimed seeds was also evaluated. All priming agents diminished the effects of salinity on endogenous abscisic acid concentration in the salt-intolerant cultivar. Grain yield was positively correlated with net CO2 assimilation rate and endogenous indoleacetic acid concentration, and it was negatively correlated with abscisic acid and free polyamine concentrations. In general, the priming treatment with tryptophan at 4.89 × 10-4 mol L-1 was the most effective in minimizing yield losses and reductions in net CO2 assimilation rate, under salt stress conditions. Hormonal homeostasis increases net CO2 assimilation rate and confers tolerance to salinity on spring wheat.

scholarly journals Foliar phosphorus supply and CO2 assimilation in common bean (Phaseolus vulgaris L.) under water deficit

2006 ◽  
Vol 18 (3) ◽  
pp. 407-411 ◽  
Author(s):  
Mauro G. dos Santos ◽  
Rafael V. Ribeiro ◽  
Marcelo G. Teixeira ◽  
Ricardo F. de Oliveira ◽  
Carlos Pimentel
Keyword(s):  
Phaseolus Vulgaris ◽  
Common Bean ◽  
Water Deficit ◽  
Co2 Assimilation ◽  
Assimilation Rate ◽  
Phaseolus Vulgaris L ◽  
Co2 Assimilation Rate ◽  
Net Co2 Assimilation ◽  
Foliar Phosphorus ◽  
Regulation Of Photosynthesis

Two common bean cultivars were grown in pots under greenhouse conditions. Plants were submitted to a foliar Pi spray two days before suspending irrigation, what enhanced net CO2 assimilation rate of Ouro Negro cultivar but did not change significantly the photosynthesis of Carioca cultivar under both water deficit and rehydration periods. The results revealed that a foliar Pi spray induced an up-regulation of photosynthesis in common bean under mild water deficit, with this effect being genotype-dependent.

scholarly journals Filtering Light-Emitting Diodes to Investigate Amber and Red Spectral Effects on Lettuce Growth

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1075
Author(s):  
Bo-Sen Wu ◽  
Sarah MacPherson ◽  
Mark Lefsrud
Keyword(s):  
Plant Growth ◽  
Photosynthetic Activity ◽  
Light Emitting Diode ◽  
Red Light ◽  
Plant Productivity ◽  
Plant Performance ◽  
Light Emitting ◽  
Amber Light ◽  
Light Spectra ◽  
Future Work

Red and blue light are the principal wavelengths responsible for driving photosynthetic activity, yet amber light (595 nm) has the highest quantum efficiency and amber-rich high pressure sodium lamps result in superior or comparable plant performance. On this basis, we investigated how lettuce plant growth and photosynthetic activity were influenced by broad and narrow light spectra in the 590–630 nm range, by creating amber and red light-emitting diode (LED) spectra that are not commercially available. Four different light spectra were outfitted from existing LEDs using shortpass and notch filters: a double peak spectrum (595 and 655 nm; referred to as 595 + 655-nm light) that excluded 630-nm light, 595-nm, 613-nm, and 633-nm light emitting at an irradiance level of 50 W·m−2 (243–267 µmol·m−2·s−1). Shifting LED wavelengths from 595 nm to 633 nm and from 595 nm to 613 nm resulted in a biomass yield decrease of ~50% and ~80%, respectively. When 630-nm light is blocked, lettuce displayed expanded plant structures and the absence of purple pigmentation. This report presents a new and feasible approach to plant photobiology studies, by removing certain wavelengths to assess and investigate wavelength effect on plant growth and photosynthesis. Findings indicate that amber light is superior to red light for promoting photosynthetic activity and plant productivity, and this could set precedence for future work aimed at maximizing plant productivity in controlled environment agriculture.

scholarly journals Interaction between soil salinity and nitrogen on growth and gaseous exchanges in guava

2018 ◽  
Vol 13 (3) ◽  
pp. 1
Author(s):  
Idelfonso Leandro Bezerra ◽  
Hans Raj Gheyi ◽  
Reginaldo Gomes Nobre ◽  
Geovani Soares de Lima ◽  
João Batista dos Santos ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Stem Diameter ◽  
Assimilation Rate ◽  
Gas Exchanges ◽  
Internal Co2 ◽  
N Dose ◽  
Number Of Leaves

This study evaluated the growth and gas exchanges of guava, cv. ‘Paluma’ cultivated in salinized soil and subjected to different nitrogen (N) doses in a protected environment in the municipality of Campina Grande-PB. The experimental design was randomized blocks, in a 5 x 4 factorial arrangement with three replicates, and the treatments resulted from the combination of five salinity levels in the soil saturation extract - ECse (2.15, 3.15,4.15, 5.15 and 6.15 dS m-1) and four N doses (70, 100, 130 and 160% of the recommended N dose). The dose referring to 100% of N corresponded to 541.1 mg of N dm-3 of soil. At 120 and 180 days after (DAT), plant growth was evaluated based on stem diameter (SD), leaf area (LA) and number of leaves (NL). At 210 DAT, the following variables of leaf gas exchanges were evaluated: stomatal conductance (gs), internal CO2 concentration (Ci), transpiration (E) and CO2 assimilation rate (A). ECse above 2.15 dS m-1 reduced stem diameter, leaf area, number of leaves, stomatal conductance, internal CO2 concentration, transpiration and CO2 assimilation rate, in both evaluation periods. N dose above 70% of the recommendation (378.7 mg N dm-3 of soil) did not mitigate the deleterious effects caused by the salt stress on the growth and gas exchanges of guava plants.

scholarly journals Blue Light-emitting Diode Light Irradiation of Seedlings Improves Seedling Quality and Growth after Transplanting in Red Leaf Lettuce

HortScience ◽  
2010 ◽  
Vol 45 (12) ◽  
pp. 1809-1814 ◽  
Author(s):  
Masahumi Johkan ◽  
Kazuhiro Shoji ◽  
Fumiyuki Goto ◽  
Shin-nosuke Hashida ◽  
Toshihiro Yoshihara
Keyword(s):  
Leaf Area ◽  
Blue Light ◽  
Antioxidant Activities ◽  
Light Emitting Diode ◽  
Red Light ◽  
Seedling Quality ◽  
Carotenoid Content ◽  
Light Emitting ◽  
Leaf Lettuce ◽  
Led Lights

In this study, we determined the effects of raising seedlings with different light spectra such as with blue, red, and blue + red light-emitting diode (LED) lights on seedling quality and yield of red leaf lettuce plants. The light treatments we used were applied for a period of 1 week and consisted of 100 μmol·m−2·s−1 of blue light, simultaneous irradiation with 50 μmol·m−2·s−1 of blue light and 50 μmol·m−2·s−1 of red light, and 100 μmol·m−2·s−1 of red light. At the end of the light treatment, that is 17 days after sowing (DAS), the leaf area and shoot fresh weight (FW) of the lettuce seedlings treated with red light increased by 33% and 25%, respectively, and the dry weight of the shoots and roots of the lettuce seedlings treated with blue-containing LED lights increased by greater than 29% and greater than 83% compared with seedlings grown under a white fluorescent lamp (FL). The shoot/root ratio and specific leaf area of plants irradiated with blue-containing LED lights decreased. At 45 DAS, higher leaf areas and FWs were obtained in lettuce plants treated with blue-containing LED lights. The total chlorophyll (Chl) contents in lettuce plants treated with blue-containing and red lights were less than that of lettuce plants treated with FL, but the Chl a/b ratio and carotenoid content increased under blue-containing LED lights. Polyphenol contents and the total antioxidant status (TAS) were greater in lettuce seedlings treated with blue-containing LED lights than in those treated with FL at 17 DAS. The higher polyphenol contents and TAS in lettuce seedlings at 17 DAS decreased in lettuce plants at 45 DAS. In conclusion, our results indicate that raising seedlings treated with blue light promoted the growth of lettuce plants after transplanting. This is likely because of high shoot and root biomasses, a high content of photosynthetic pigments, and high antioxidant activities in the lettuce seedlings before transplanting. The compact morphology of lettuce seedlings treated with blue LED light would be also useful for transplanting.

scholarly journals Intrinsic Fluctuations in Transpiration Induce Photorespiration to Oxidize P700 in Photosystem I

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1761
Author(s):  
Riu Furutani ◽  
Amane Makino ◽  
Yuij Suzuki ◽  
Shinya Wada ◽  
Ginga Shimakawa ◽  
...  
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
Co2 Assimilation ◽  
Proton Gradient ◽  
Assimilation Rate ◽  
Oxidation Level ◽  
Co2 Assimilation Rate ◽  
Net Co2 Assimilation Rate ◽  
Net Co2 Assimilation ◽  
Intrinsic Fluctuations

Upon exposure to environmental stress, the primary electron donor in photosystem I (PSI), P700, is oxidized to suppress the production of reactive oxygen species that could oxidatively inactivate the function of PSI. The illumination of rice leaves with actinic light induces intrinsic fluctuations in the opening and closing of stomata, causing the net CO2 assimilation rate to fluctuate. We examined the effects of these intrinsic fluctuations on electron transport reactions. Under atmospheric O2 conditions (21 kPa), the effective quantum yield of photosystem II (PSII) (Y(II)) remained relatively high while the net CO2 assimilation rate fluctuated, which indicates the function of alternative electron flow. By contrast, under low O2 conditions (2 kPa), Y(II) fluctuated. These results suggest that photorespiration primarily drove the alternative electron flow. Photorespiration maintained the oxidation level of ferredoxin (Fd) throughout the fluctuation of the net CO2 assimilation rate. Moreover, the relative activity of photorespiration was correlated with both the oxidation level of P700 and the magnitude of the proton gradient across the thylakoid membrane in 21 kPa O2 conditions. These results show that photorespiration oxidized P700 by stimulating the proton gradient formation when CO2 assimilation was suppressed by stomatal closure.

Sign in / Sign up

Export Citation Format

Share Document