Carbon dioxide exchange and phytochrome control of flowering in Xanthium pennsylvanicum

1976 ◽  
Vol 54 (24) ◽  
pp. 2881-2887 ◽  
Author(s):  
P. K. Bassi ◽  
E. B. Tregunna ◽  
P. A. Jolliffe
Keyword(s):  
Carbon Dioxide ◽  
Red Light ◽  
Light Treatment ◽  
Carbon Dioxide Exchange ◽  
Low Intensity ◽  
Apparent Relationship ◽  
Light Effects ◽  
High Concentrations ◽  
Subsequent Flowering ◽  
Bud Morphology

The presence of CO2 at sufficiently high concentrations is necessary for red light night interruptions to affect flowering in Xanthium pennsylvanicum L. The present study investigated the involvement of CO2 exchange in the effects of night interruptions on flowering. Brief red or far-red treatments were applied to Xanthium plants under inductive night conditions, and flowering response was assessed according to bud morphology 10 days after light treatment. The occurrence of flowering depended on the timing, wavelength, and intensity of the light treatments and on the CO2 concentration during the treatments. During the night interruptions CO2 exchange was measured in single attached leaves. CO2 exchange was influenced by the conditions during the night interruptions, but there was no apparent relationship between the patterns of CO2 exchange observed and the subsequent flowering responses to the night interruptions. Brief (10–60 s) high-intensity red light interruptions at 350 ppm CO2 had much less effect on CO2 exchange than did 5 min of low-intensity red light interruptions given at 20 ppm CO2. The brief light interruptions inhibited flowering, while the longer interruptions at low CO2 concentrations were ineffective. Moreover, far-red reversal of red light effects was not accompanied by alterations in CO2 exchange. It appears that the action of CO2 in night interruptions is not associated with CO2 exchange during the interruptions.

Die Wirkung von Phytochrom auf die Bildung von Einzelcarotinoiden in etiolierten Horde um -Keimlingen / The Influence of Phytochrome on the Formation of Individual Carotenoids in Etiolated Hordeum Seedlings

1975 ◽  
Vol 30 (1-2) ◽  
pp. 67-68 ◽  
Author(s):  
Hans K. Kleudgen ◽  
Hartmut K. Lichtenthaler
Keyword(s):  
White Light ◽  
Accumulation Rate ◽  
Red Light ◽  
Light Treatment ◽  
Light Effects ◽  
Short Time ◽  
Β Carotene

Abstract Short time red pulses, given 6 times for 5 min within 36 h, induce in etiolated barley seedlings an enhanced synthesis of the main chloroplast carotenoids β-carotene, violaxanthine, lutein and neoxanthine. The level of antheraxanthine and zeaxanthine decreases by red light treatment. These red light effects are reverted by subsequent short time far-red pulses. The results show that the white light induced change in the accumulation rate of individual carotenoids is initiated and regulated by active phytochrome Pfr . In the case of neoxanthin and zeaxanthin the red light effects cannot be fully reverted by far-red; this points to very fast phytochrome reaction.

scholarly journals Preliminary study of the production of metabolites from in vitro cultures of C. ensiformis

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Juan F. Saldarriaga ◽  
Yuby Cruz ◽  
Julián E. López
Keyword(s):  
Antioxidant Activity ◽  
Bioactive Compounds ◽  
Culture Medium ◽  
Red Light ◽  
Light Treatment ◽  
Different Types ◽  
Light Effects ◽  
Preliminary Study ◽  
The Ideal

Abstract Background Canavalia ensiformis is a legume native to Central and South America that has historically been a source of protein. Its main proteins, urease, and lectin have been extensively studied and are examples of bioactive compounds. In this work, the effect of pH and light effects on the growth of C. ensiformis were analyzed. Also, the bioactive compounds such as phenols, carotenoids, chlorophyll a/b, and the growth of callus biomass of C. ensiformis from the effect of different types of light treatments (red, blue and mixture) were evaluated. Likewise, the antioxidative activity of C. ensiformis extracts were studied and related to the production of bioactive compounds. For this, a culture of calluses obtained from seeds were carried out. For the light experiments, polypropylene boxes with red, blue, combination (1/3, 3/1 and 1/1 R-B, respectively) lights and white LED were used as control. In each treatment, three glass containers with 25 ml of MS salts containing 0.25 g of fresh callus were seeded. Results The results have shown that the pH of the culture medium notably affects the increase in callogenic biomass. It shows that the pH of 5.5 shows better results in the callogenic growth of C. ensiformis with an average increase of 1.3051 g (198.04%), regarding the initial weight. It was found that the pH 5.5 and the 1/3 R-B LED combination had higher production of bioactive compounds and better antioxidant activity. At the same time, the red-light treatment was least effective. Conclusions It was possible to find the ideal conditions of important growth under conditions of pH and light of C. ensiformis. Likewise, it is evaluated whether the production of compounds of interest, such as phenolic compounds and carotenoids, occurs under these conditions. The highest production of calluses occurs in the 1/3 R-B LED combined light treatment, which showed a significant increase in biomass, followed by B. From this study, it could be demonstrated that C. ensiformis produces compounds such as phenols and carotenoids in vitro culture that are essential for the antioxidant activity of the plant.

scholarly journals Single Wavelengths of LED Light Supplement Promote the Biosynthesis of Major Cyclic Monoterpenes in Japanese Mint

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1420
Author(s):  
Takahiro Ueda ◽  
Miki Murata ◽  
Ken Yokawa
Keyword(s):  
Blue Light ◽  
Solid Phase ◽  
Glandular Trichomes ◽  
Red Light ◽  
Glandular Trichome ◽  
Pulse Amplitude ◽  
Light Treatment ◽  
Led Light ◽  
Trichome Formation ◽  
Japanese Mint

Environmental light conditions influence the biosynthesis of monoterpenes in the mint plant. Cyclic terpenes, such as menthol, menthone, pulegone, and menthofuran, are major odor components synthesized in mint leaves. However, it is unclear how light for cultivation affects the contents of these compounds. Artificial lighting using light-emitting diodes (LEDs) for plant cultivation has the advantage of preferential wavelength control. Here, we monitored monoterpene contents in hydroponically cultivated Japanese mint leaves under blue, red, or far-red wavelengths of LED light supplements. Volatile cyclic monoterpenes, pulegone, menthone, menthol, and menthofuran were quantified using the head-space solid phase microextraction method. As a result, all light wavelengths promoted the biosynthesis of the compounds. Remarkably, two weeks of blue-light supplement increased all compounds: pulegone (362% increase compared to the control), menthofuran (285%), menthone (223%), and menthol (389%). Red light slightly promoted pulegone (256%), menthofuran (178%), and menthol (197%). Interestingly, the accumulation of menthone (229%) or menthofuran (339%) was observed with far-red light treatment. The quantification of glandular trichomes density revealed that no increase under light supplement was confirmed. Blue light treatment even suppressed the glandular trichome formation. No promotion of photosynthesis was observed by pulse-amplitude-modulation (PAM) fluorometry. The present result indicates that light supplements directly promoted the biosynthetic pathways of cyclic monoterpenes.

737 Prediction of drop out in an adjunctive light treatment trial in patients with non-seasonal depression and evening chronotype

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A287-A288
Author(s):  
Joey W Chan ◽  
Y K Wing ◽  
S P Lam ◽  
Shirley Xin Li ◽  
J Zhang
Keyword(s):  
Clinical Characteristics ◽  
Red Light ◽  
Bright Light ◽  
Fold Increase ◽  
Light Therapy ◽  
Light Treatment ◽  
Drop Out ◽  
Sleep Diary ◽  
Significant Difference ◽  
Seasonal Depression

Abstract Introduction Drop out during treatment hampers therapeutic effect of interventions. The current study examines the possible predictors of drop out during the five-week light treatment in patients with unipolar non-seasonal depression and evening-chronotype. Methods Baseline characteristics including demographics, sleep diary parameters, light treatment prescribed, and early clinical outcomes changes were compared between the Drop out and Non drop out group. Logistic regression analysis was used to examine predictors for drop out. All data were analyzed in a modified intention to treat analysis with last observation carried forward approach. Results A total of 91 subjects (Female 79%, 46.3 ± 11.8 years old) were included in the analysis. There was no significant difference in the baseline demographic and clinical characteristics between the Drop out and Non drop out group. There was also no significant difference in the improvement of clinical parameters over the first week among the two groups. However, treatment non-adherence (in terms of compliance of less than 80% of prescribed duration) over the first treatment week predicts a five-fold increase in risk of drop out during light therapy. (OR: 5.85, CI: 1.414–24.205, p=0.015) after controlling for potential confounders including age, gender, treatment group, patient expectation, and treatment-emergent adverse events. Conclusion This study found that baseline clinical characteristics including depression severity and improvement of depressive symptoms in the initial week did not differ between the Drop out and Non drop out group. The drop out was also not affected by the type of light (dim red versus bright red light), indirectly supporting dim red light as a valid placebo in bright light therapy trial. Treatment adherence is the early phase of light treatment is an important predictor of drop out. Support (if any):

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