The inhibitory effect of light on seed and burr development in several species of Trifolium

1979 ◽  
Vol 30 (5) ◽  
pp. 895 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Light Intensity ◽  
Seed Development ◽  
Subterranean Clover ◽  
Light Response ◽  
Inhibitory Effect ◽  
Low Light ◽  
Effect Of Light

The effect of light on seed and burr development was studied in 20 genotypes from four species of Trifolium. Burrs produced from spaced laterals were enclosed in plastic tubes variously shaded to produce a range of light treatments. Light inhibited seed development to varying degrees in a range of subterranean clovers, which included strains of T. israeliticum and of all three subspecies of T. subterraneum. In four strains studied intensively the weight of seeds per burr decreased linearly with increases in the logarithm of the light intensity. Light had no effect on seed development in two other geocarpic species, T. batmanicum and T. globosum, which do not actually bury their burrs. The weight of both the pod walls (pericarps) and the sterile calyces was reduced by light in all strains of T. subterraneum. Light also reduced the weight of pod walls in T. israeliticum but had little effect on the production of sterile calyces. Variation in the pattern of light response between plants of the Seaton Park strain of T. subterraneum was found to be associated with genetically distinct lines. Four of the subterranean clover strains commonly produced twin-seeded pods in dark and low light treatments. The incidence of twinning in these strains appeared to be greater than that normally encountered in buried burrs. The ranking of strains of T. subterraneum for susceptibility to light agreed reasonably well with the ranking of the same strains, by others, for seed development above ground. Seaton Park and, to a lesser extent, Dinninup were exceptions in that they were more severely inhibited by light than by lack of burr burial. It is suggested that another factor in addition to light may be involved in the response to burr burial.

The inhibitory effect of light on seed development in subterranean clover (Trifolium subterraneum L.)

1976 ◽  
Vol 27 (2) ◽  
pp. 207 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Seed Development ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Moisture Stress ◽  
Inhibitory Effect ◽  
Atmospheric Moisture ◽  
Dark Treatment ◽  
Poor Seed ◽  
Development Processes ◽  
Effect Of Light

Explanations were sought for the poor seed development commonly found in unburied burrs of subterranean clover. In the first of two experiments, the effects of light and of atmospheric moisture stress on seed development in subterranean clover (cv. Daliak) were examined. Burrs produced from spaced laterals were enclosed in plastic tubes variously shaded to permit the entry of 0, 5, 19, 48 and 100% daylight. The tubes were further allocated to two groups. Air was continuously passed through tubes of one group to produce an atmospheric moisture stress, while those of the other group were not subjected to air flow. There was a marked effect of light on seed development. Mean seed weight was reduced from c. 11 mg in the dark treatment to 4 mg at only 5% daylight and to 2 mg in the 100% daylight treatment. Seed numbers were reduced significantly, from four to c. two seeds per burr, in the 100% daylight treatment only. There was virtually no effect of atmospheric moisture stress on either seed set or seed size. In the second experiment, a study was made of the effect of timing of burr burial on seed development processes. Fertilization does not appear to be implicated but both cell division and cell enlargement were influenced by the state of burial and, presumably, by light.

Influence of Fluridone on Chlorophyll Content of Wheat (Triticum aestivum) and Corn (Zea mays)

Weed Science ◽  
1978 ◽  
Vol 26 (5) ◽  
pp. 432-433 ◽  
Author(s):  
R. M. Devlin ◽  
C. N. Saras ◽  
M. J. Kisiel ◽  
A. S. Kostusiak
Keyword(s):  
Triticum Aestivum ◽  
Zea Mays ◽  
Light Intensity ◽  
Chlorophyll Content ◽  
High Light Intensity ◽  
Carotenoid Content ◽  
Low Light ◽  
Low Light Intensity ◽  
Chlorophyll Production ◽  
Effect Of Light

Chlorophyll content of wheat (Triticum aestivum L. ‘Mericopa’) and corn (Zea mays L. ‘Merit’) treated with the herbicide fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)-phenyl]-4(1H)-pyridinone} and grown under high light intensity (10.8 klux), was markedly reduced. Corn and wheat germinated from seeds treated with 10 uM fluridone and grown for 6 days were almost completely bleached. Under low light intensity (108 lux) the influence of fluridone on chlorophyll production was greatly reduced. Under very low light intensity (21.5 lux) this influence was almost completely lost. The effect of light on the activity of fluridone suggests that the inhibition of carotenoid production may represent the mode of action of this herbicide. This study shows that the carotenoid content of wheat or corn drops dramatically when these plants are treated with fluridone.

NATURAL ANTIOXIDANT ACTIVITY IN SOME MICROALGAL SPECIES

1998 ◽  
Vol 46 (2) ◽  
pp. 169-176 ◽  
Author(s):  
Alexander Perelman ◽  
Ritsuko Matsukawa ◽  
Michal Schlosberg ◽  
Bat-Sheva Cohen ◽  
Claude Fostik-Magyar ◽  
...  
Keyword(s):  
Light Intensity ◽  
Food Additives ◽  
Water Soluble ◽  
Cell Cytoplasm ◽  
Low Light ◽  
Natural Substances ◽  
Harmful Effects ◽  
Microalgal Species ◽  
Soluble Components ◽  
Effect Of Light

At the present time there is an increasing awareness of the potential harmful effects of various chemical food additives used to delay spoilage. This resulted in the search for natural substances which may prevent oxidation of various lipids, a main cause of the onset of rancidity. Various algae were examined for their potential as sources of antioxidants. As part of that search, the amount of doublebonds in their constituent compounds and their antioxidant (AO) and lipoxygenase (LOX) activities were followed in some microalgal species. The effect of light intensity, salinity, and temperature on the AO activity of lipid extracts from the microalgaNaviculasp. was studied. Maximum AO activity was obtained inNaviculagrown under low light intensity. AO activity of various algal fractions was studied both as inhibition of LOX activity and of linoleate autooxidation. Most of the LOX inhibitive activity was found in the membranal lipid-soluble fractions, whereas the inhibition of autooxidation was associated with the water-soluble components of the cell cytoplasm.

scholarly journals Effect of light intensity and growth substratum on plant development and production of secondary metabolites in Cordia curassavica (Jacq.) Roem. & Schult

2010 ◽  
Vol 34 (3) ◽  
pp. 417-423 ◽  
Author(s):  
Maria Terezinha Silveira Paulilo ◽  
Flávia Simão Lapa ◽  
Miriam de Barcellos Falkenberg
Keyword(s):  
Light Intensity ◽  
Root Biomass ◽  
Relative Income ◽  
High Light Intensity ◽  
High Light ◽  
Alcoholic Extract ◽  
Low Light ◽  
Fertilized Soil ◽  
Lower Light ◽  
Effect Of Light

Cordia curassavica (Jacq.) Roem. & Schult. (Boraginaceae), also referred to as Cordia verbenacea DC, has been traditionally used for medicinal purposes. This study was driven to verify the behavior of the species in similar conditions to its natural environment, such as high light intensity and sandbank soil, and in conditions of low light intensity and fertilized substratum (dystroferric red nitosoil plus earthworm humus). The growth of the plant, the income of leaf crude extracts and, in the alcoholic extract, the number of substances found in thin layer cromatography and the toxicity of the substratum was observed. The results indicated that the growth of the root biomass, stem and leaves in discharge or lower light intensity was similar, but smaller in sandbank soil than in fertilized soil. The relative income of extracts in ether of petroleum and alcohol was larger in high light intensity and fertilized substratum. The light intensity and the substratum type didn't affect the number of substances detected in the alcoholic extract or the toxicity of this extract. Stains corresponding to the rosmarinic acid were only evidenced in some samples of the alcoholic extract, not allowing the verification of the effect of the treatments about its production.

scholarly journals Photochemical Acclimation of Three Contrasting Species to Different Light Levels: Implications for Optimizing Supplemental Lighting

2017 ◽  
Vol 142 (5) ◽  
pp. 346-354 ◽  
Author(s):  
Shuyang Zhen ◽  
Marc W. van Iersel
Keyword(s):  
Electron Transport ◽  
Light Intensity ◽  
Photochemical Efficiency ◽  
Light Response ◽  
High Light ◽  
Photon Flux ◽  
Ambient Light ◽  
Response Curves ◽  
Low Light ◽  
Supplemental Lighting

Photosynthetic responses to light are dependent on light intensity, vary among species, and can be affected by acclimation to different light environments (e.g., light intensity, spectrum, and photoperiod). Understanding how these factors affect photochemistry is important for improving supplemental lighting efficiency in controlled-environment agriculture. We used chlorophyll fluorescence to determine photochemical light response curves of three horticultural crops with contrasting light requirements [sweetpotato (Ipomea batatas), lettuce (Lactuca sativa), and pothos (Epipremnum aureum)]. We also quantified how these responses were affected by acclimation to three shading treatments-full sun, 44% shade, and 75% shade. The quantum yield of photosystem II (ΦPSII), a measure of photochemical efficiency, decreased exponentially with increasing photosynthetic photon flux (PPF) in all three species. By contrast, linear electron transport rate (ETR) increased asymptotically with increasing PPF. Within each shading level, the high-light-adapted species sweetpotato used high light more efficiently for electron transport than light-intermediate lettuce and shade-tolerant pothos. Within a species, plants acclimated to high light (full sun) tended to have higher ΦPSII and ETR than those acclimated to low light (44% or 75% shade). Nonphotochemical quenching (NPQ) (an indicator of the amount of absorbed light energy that is dissipated as heat) was upregulated with increasing PPF; faster upregulation was observed in pothos as well as in plants grown under 75% shade. Our results have implications for supplemental lighting: supplemental light is used more efficiently and results in a greater increase in ETR when provided at low ambient PPF. In addition, high-light-adapted crops and crops grown under relatively high ambient light can use supplemental light more efficiently than low-light-adapted crops or those grown under low ambient light.

scholarly journals The effect of light on N<sub>2</sub> fixation and net nitrogen release of field <i>Trichodesmium</i>

2017 ◽  
Author(s):  
Yangyang Lu ◽  
Zuozhu Wen ◽  
Dalin Shi ◽  
Mingming Chen ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Light Intensity ◽  
Model Prediction ◽  
Carbon Fixation ◽  
Physiological State ◽  
Light Stress ◽  
Light Response ◽  
Light Change ◽  
Filamentous Cyanobacterium ◽  
Net Release ◽  
Effect Of Light

Abstract. Dinitrogen fixation (NF) by marine cyanobacteria is a crucial pathway to replenish the oceanic bioavailable nitrogen inventory. Light is the key to modulate NF, however, field studies regarding light response curve (NF-I curve) of NF rate and the effect of light on diazotroph derived nitrogen (DDN) net release are missing that may hamper an accurate nitrogen model prediction. Uncontaminated 15N2 gas dissolution method was applied to examine how the light change may influence the NF intensity and DDN net release in the oligotrophic ocean. Experiments were conducted at stations with diazotrophs dominated by filamentous cyanobacterium Trichodesmium spp. in the Western Pacific and the South China Sea. The light effect on carbon fixation (CF) was measured in parallel using the 13C labelling method specifically for a station characterized by Trichodesmium bloom. Both NF-I and CF-I curves showed Ik (light saturation coefficient) range of 328 to 509 μE m−2 s−1 with saturation light at around 600 μE m−2 s−1. The proportion of DDN net release ranged from ~6% to ~50% revealing an increasing trend as the light intensity decreased. At the Trichodesmium bloom station, we found CF/NF ratio was light-dependent and the ratio started to increase as light was lower than the carbon compensation point of 300 μE m−2 s−1. NF pathway was likely preferentially blocked under low light to conserve energy for photosynthesis, thus, there is a metabolism tradeoff between carbon and nitrogen fixation pathways under light stress. Results showed that short-term light change modulates the physiological state, which subsequently determined the C/N metabolism and DDN net release of field Trichodesmium. Energy reallocation associated with the variations of field light intensity would be helpful for model prediction of global biogeochemical cycle involved with Trichodesmium.

scholarly journals Light Regulates the Cytokinin-Dependent Cold Stress Responses in Arabidopsis

2021 ◽  
Vol 11 ◽  
Author(s):  
Sylva Prerostova ◽  
Martin Černý ◽  
Petre I. Dobrev ◽  
Vaclav Motyka ◽  
Lucia Hluskova ◽  
...  
Keyword(s):  
Light Intensity ◽  
Cold Stress ◽  
Stress Tolerance ◽  
Stress Responses ◽  
Cold Treatment ◽  
Cytokinin Oxidase ◽  
Low Light ◽  
Cold Response ◽  
The Impact ◽  
Effect Of Light

To elucidate the effect of light intensity on the cold response (5°C; 7 days) in Arabidopsis thaliana, we compared the following parameters under standard light (150 μmol m–2 s–1), low light (20 μmol m–2 s–1), and dark conditions: membrane damage, photosynthetic parameters, cytokinin oxidase/dehydrogenase (CKX) activity, phytohormone levels, and transcription of selected stress- and hormone-related genes and proteome. The impact of cytokinins (CKs), hormones directly interacting with the light signaling pathway, on cold responses was evaluated using transformants overexpressing CK biosynthetic gene isopentenyl transferase (DEX:IPT) or CK degradation gene HvCKX2 (DEX:CKX) under a dexamethasone-inducible promoter. In wild-type plants, cold treatment under light conditions caused down-regulation of CKs (in shoots) and auxin, while abscisic acid (ABA), jasmonates, and salicylic acid (SA) were up-regulated, especially under low light. Cold treatment in the dark strongly suppressed all phytohormones, except ABA. DEX:IPT plants showed enhanced stress tolerance associated with elevated CK and SA levels in shoots and auxin in apices. Contrarily, DEX:CKX plants had weaker stress tolerance accompanied by lowered levels of CKs and auxins. Nevertheless, cold substantially diminished the impact from the inserted genes. Cold stress in dark minimized differences among the genotypes. Cold treatments in light strongly up-regulated stress marker genes RD29A, especially in roots, and CBF1-3 in shoots. Under control conditions, their levels were higher in DEX:CKX plants, but after 7-day stress, DEX:IPT plants exhibited the highest transcription. Transcription of genes related to CK metabolism and signaling showed a tendency to re-establish, at least partially, CK homeostasis in both transformants. Up-regulation of strigolactone-related genes in apices and leaves indicated their role in suppressing shoot growth. The analysis of leaf proteome revealed over 20,000 peptides, representing 3,800 proteins and 2,212 protein families (data available via ProteomeXchange, identifier PXD020480). Cold stress induced proteins involved in ABA and jasmonate metabolism, antioxidant enzymes, and enzymes of flavonoid and glucosinolate biosynthesis. DEX:IPT plants up-regulated phospholipase D and MAP-kinase 4. Cold stress response at the proteome level was similar in all genotypes under optimal light intensity, differing significantly under low light. The data characterized the decisive effect of light–CK cross-talk in the regulation of cold stress responses.

Differential Regulation of Flavone Glycosylation during Ontogeny of Silene pratensis

1983 ◽  
Vol 38 (7-8) ◽  
pp. 544-548 ◽  
Author(s):  
J. M. Steyns ◽  
G. van Nigtevecht ◽  
G. J. Niemann ◽  
J. v. Brederode
Keyword(s):  
Light Intensity ◽  
Differential Regulation ◽  
Low Light ◽  
Leaf Pair ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Flower Stem ◽  
Pair Number ◽  
Silene Pratensis ◽  
Effect Of Light

Two isovitexin glycosides have been found in the cotyledons and foliage leaves of Sitene pratensis plants that are unable to glycosylate isovitexin in their petals (genotype gg glgl fgfg). The glycosides (isovitexin 7-O-galactoside and isovitexin 7-O-galactose 2″-O-arabinoside) were present only in the lower leaves: leaves produced later in the development of the flower stem accumulated only the aglycon isovitexin. The transition in the flavone composition during the ontogeny of the plants could be influenced by light intensity. In plants grown at low light intensity, glycoside production continued until a higher leaf pair number than in plants grown at higher light intensities. However, the effect of light intensity is indirect: the transition in the flavone composition is correlated with the transition from rosette leaves to stem leaves. The presence of the 7-O-galactosides in cotyledons and rosette leaves suggests that in addition to the g, gl and fg loci, there are further glycosylating loci which are not expressed in stem leaves and petals.

scholarly journals Effect of light on N<sub>2</sub> fixation and net nitrogen release of <i>Trichodesmium</i> in a field study

2018 ◽  
Vol 15 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Yangyang Lu ◽  
Zuozhu Wen ◽  
Dalin Shi ◽  
Mingming Chen ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Light Intensity ◽  
Carbon Fixation ◽  
Physiological State ◽  
Light Stress ◽  
Light Response ◽  
Light Change ◽  
Filamentous Cyanobacterium ◽  
Light Saturation ◽  
Net Release ◽  
Effect Of Light

Abstract. Dinitrogen fixation (NF) by marine cyanobacteria is an important pathway to replenish the oceanic bioavailable nitrogen inventory. Light is the key to modulating NF; however, field studies investigating the light response curve (NF-I curve) of NF rate and the effect of light on diazotroph-derived nitrogen (DDN) net release are relatively sparse in the literature, hampering prediction using models. A dissolution method was applied using uncontaminated 15N2 gas to examine how the light changes may influence the NF intensity and DDN net release in the oligotrophic ocean. Experiments were conducted at stations with diazotrophs dominated by filamentous cyanobacterium Trichodesmium spp. in the western Pacific and the South China Sea. The effect of light on carbon fixation (CF) was measured in parallel using the 13C tracer method specifically for a station characterized by Trichodesmium bloom. Both NF-I and CF-I curves showed a Ik (light saturation coefficient) range of 193 to 315 µE m−2 s−1, with light saturation at around 400 µE m−2 s−1. The proportion of DDN net release ranged from ∼ 6 to ∼ 50 %, suggesting an increasing trend as the light intensity decreased. At the Trichodesmium bloom station, we found that the CF ∕ NF ratio was light-dependent and the ratio started to increase as light was lower than the carbon compensation point of 200 µE m−2 s−1. Under low-light stress, Trichodesmium physiologically preferred to allocate more energy for CF to alleviate the intensive carbon consumption by respiration; thus, there is a metabolism tradeoff between CF and NF pathways. Results showed that short-term (< 24 h) light change modulates the physiological state, which subsequently determined the C ∕ N metabolism and DDN net release by Trichodesmium. Reallocation of energy associated with the variation in light intensity would be helpful for prediction of the global biogeochemical cycle of N by models involving Trichodesmium blooms.

Factors affecting growith and distribution of kauri (Agathis australis Salisb.) I. Effect of light on the establishment of Kaura and of Phyllocladus trichomanoides D.Don

1959 ◽  
Vol 7 (3) ◽  
pp. 252 ◽  
Author(s):  
RL Bieleski
Keyword(s):  
Light Intensity ◽  
Frequency Distribution ◽  
High Light Intensity ◽  
High Light ◽  
Low Light ◽  
Factors Affecting ◽  
Light Intensities ◽  
Seedling Distribution ◽  
Conifer Seedling ◽  
Effect Of Light

A method for determining the effect of light on seedling distribution in the field is described. It can be applied when seedling frequencies are as low as 1/m2. The frequency distribution of light intensities occupied by seedlings in a quadrat is compared with the frequency distribution of light intensities measured on a grid in the quadrat. This method was used to study the effect of light intensity on the establishment of two New Zealand gymnosperms, kauri (Agathis australis) and Phyllocladus trichomanoides, in the nursery community, a semimature Leptospermum scoparium – L. ericoides associes. Kauri and Phyllocladus did not occur at light intensities below 0.015 and 0.018 full daylight respectively. This limitation appeared to be due to the low light intensity presumably limiting photosynthesis. Kauri, but not Phyllocladus, also showed a high light intensity limit, at 0.30 full daylight, above which seedlings did not establish. Reasons are given for considering this as an indirect effect, probably through related solar heating affecting soil temperature or moisture. The optimal light intensity for kauri and Phyllocladus seedling establishment was close to the modal light intensity under the Leptospermum community: Leptospermum spp. were incapable of regenerating under their own cover. These two reasons appear to explain the suitability of the Leptospermum community as a nurse crop for the two conifer seedling species.

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