Effect Of Different Light Intensities Research Articles

Effects of different light intensities on growth, survival, reproductive and life span characteristics ofArtemia urmiana(Günther 1890)

Effects of light intensities on growth, survival, reproductive and life span traits of Artemia urmiana were investigated under laboratory conditions. Nauplii of A. urmiana were hatched and raised in 100 g L−1 at four illuminations including 0, 100, 2000 and 5000 lx with 14:10 (light:dark) photoperiod. Mating pairs of mature animals were randomly isolated and reared continuously under similar conditions. The mode and potential of reproduction as well as adult survival shown by each pair were determined throughout their life span. Results showed that percentages of nauplii survival were significantly (P ≤ 0.05) different at 5000 and 0 lx (76.50% compared with 26.25%) respectively. Total number of offspring was highly correlated with the light intensities showing increased numbers at higher light intensities compared with darkness or 100 lx. Reproduction mode was relatively affected by various light intensities. Significant (P ≤ 0.05) differences were found both in reproductive period and life span at different illuminations. Maximum and minimum offspring productions per reproductive day were found at 5000 and 100 lx respectively. The relative degree of oviparity increased as the illumination decreased (57.92% compared with 22.65% at 0 and 5000 lx respectively). The optimum light intensities appear to be between 2000 lx and 5000 lx in this study. These findings could probably be useful for mass culture of A. urmiana in indoor or recirculating systems as well as in outdoor systems for intensive cyst and biomass production.

Light is a positive regulator of strigolactone levels in tomato roots

Strigolactones (SLs) or closely related molecules were recently identified as phytohormones, acting as long-distance branching factors that suppress growth of pre-formed axillary buds in the shoot. The SL signaling pathways and light appear to be connected, as SLs were shown to induce light-regulated pathways and to mimic light-adapted plant growth. However, it is not yet clear how light affects SL levels. Here, we examined the effect of different light intensities on SL levels in tomato roots. The results show that light intensity, above a certain threshold, is a positive regulator of SL levels and of Sl-CCD7 transcription; Sl-CCD7 is involved in SLs biosynthesis in tomato. Moreover, SL accumulation in plant roots is shown to be a time-dependent process. At least some of the similar effects of light and SLs on plant responses might result from a positive effect of light on SL levels.

Effects of Different Light Intensities in the Morning on Dim Light Melatonin Onset

The present study evaluated the effects of exposure to light intensity in the morning on dim light melatonin onset (DLMO). The tested light intensities were 750 lux, 150 lux, 3000 lux, 6000 lux and 12,000 lux (horizontal illuminance at cornea), using commercial 5000 K fluorescent lamps. Eleven healthy males aged 21-31 participated in 2-day experiments for each light condition. On the first experimental day (day 1), subjects were exposed to dim light (<30 lux) for 3 h in the morning (09:00-12:00). On the same day, saliva samples were taken in dim light (<30 lux) every 30 min from 21:00 to 01:00 to determine the DLMO phase. The subjects were allowed to sleep from 01:00 to 08:00. On the second experimental day (day 2), the subjects were exposed to experimental light conditions for 3 h in the morning. The experimental schedule after light exposure was the same as on day 1. On comparing day 2 with day 1, significant phase advances of DLMO were obtained at 3000 lux, 6000 lux and 12,000 lux. These findings indicate that exposure to a necessary intensity from an ordinary light source, such as a fluorescent lamp, in the morning within one day affects melatonin secretion.

Effect of different light intensities on total phenolics and flavonoids synthesis and anti-oxidant activities in young ginger varieties (Zingiber officinale Roscoe).

Nowadays, phytochemicals and antioxidants in plants are raising interest in consumers for their roles in the maintenance of human health. Phenolics and flavonoids are known for their health-promoting properties due to protective effects against cardiovascular disease, cancers and other disease. Ginger (Zingiber officinale) is one of the traditional folk medicinal plants and it is widely used in cooking in Malaysia. In this study, four levels of glasshouse light intensities (310, 460, 630 and 790 μmol m−2s−1) were used in order to consider the effect of light intensity on the production, accumulation and partitioning of total phenolics (TP), total flavonoids (TF) and antioxidant activities in two varieties of Malaysian young ginger (Zingiber officinale). TF biosynthesis was highest in the Halia Bara variety under 310 μmol m−2s−1 and TP was high in this variety under a light intensity of 790 μmol m−2s−1. The highest amount of these components accumulated in the leaves and after that in the rhizomes. Also, antioxidant activities determined by the 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) assay in both of varieties, increased significantly (p ≤ 0.01) with increasing TF concentration, and high antioxidant activity was observed in the leaves of Halia Bara grown under 310 μmol m−2s−1. The ferric reducing (FRAP) activity of the rhizomes was higher than that of the leaves in 310 μmol m−2s−1 of sun light. This study indicates the ability of different light intensities to enhance the medicinal components and antioxidant activities of the leaves and young rhizomes of Zingiber officinale varieties. Additionally, this study also validated their medicinal potential based on TF and TP contents.

Light-induced accumulation of ortho-dihydroxylated flavonoids as non-destructively monitored by chlorophyll fluorescence excitation techniques

Chlorophyll fluorescence excitation techniques have been used in plant science for more than one decade to non-destructively estimate phenolic compounds in the epidermal cell layer. These techniques have been used here to evaluate the effect of different light intensities and spectral quality on the accumulation of ortho-dihydroxylated flavonoids in Phyllirea latifolia L., Myrtus communis L. and Ligustrum vulgare L. In a first experiment, chlorophyll fluorescence excitation spectra were measured (with a double arm optical fiber bundle connected to a spectrofluorimeter) on the adaxial and abaxial leaf surfaces of container-grown P. latifolia and M. communis exposed to 20% or 100% full sunlight. Differences in epidermal absorption spectra (referred to as epidermal absorption spectra throughout the paper) were then calculated from the relative chlorophyll fluorescence excitation spectra. This allowed comparing the content of UV-absorbing compounds between differentially irradiated leaves as well as between adaxial and abaxial epidermal layers. The absorption spectra were characterized by a band centered at 360–380 nm, which was greater in sun than in shade leaves and in the adaxial than in the abaxial surfaces, irrespective of species. Based upon HPLC-DAD and HPLC–MS analyses of leaf extracts and UV-spectral features of individual flavonoids, we conclude that quercetin, luteolin and myricetin derivatives were responsible for the observed light-induced changes in the spectral features of examined tissues. In a second experiment, we grew L. vulgare potted plants at 30% or 85% full sunlight in the presence or in the absence of UV radiation. We measured the absorbance characteristics at 370 nm of three leaf-pairs located in the apical portion of each shoot, using a portable fluorimetric sensor, the Multiplex ®. This allowed estimating, non-destructively, an index closely related to the concentration of epidermal flavonols and flavones having an ortho-dihydroxyl substitution in the B-ring. This index was greater in leaves growing at 85% than at 30% sunlight, irrespective of UV irradiance. When plants acclimated for 3 weeks to 30% sunlight, in the presence or in the absence of UV irradiance, were transferred to 85% sunlight, the flavonoid index exponentially increased, reaching a maximum within 10 days. On the whole, our experiments conclusively show that light-responsive flavonoids are mostly the dihydroxy B-ring-substituted structures. These flavonoids are the most effective, among the wide array of flavonoid structures, in preventing the generation and scavenging reactive oxygen species. As a consequence, we suggest that flavonoids do not merely serve as UV-screening agents, but behave as ROS-detoxifying agents in the mechanisms of photoprotection.

Effects of different light intensities on quality of spermatozoa in rabbits

The present study evaluated the effects of light intensity on semen production in rabbits. Bucks were allocated to two groups which were exposed to a lighting program (16L:8D) with different light intensities (Group 1: &lt;100 Lux; Group 2: &gt;200 Lux). Prior to the thirteen weeks duration of the examination period, bucks were adapted to the light system for two months and conditioned for semen collection for one month. There was no effect of light intensity on libido, concentration and motility of spermatozoa. However, there were more bucks in group 1 delivering ejaculate with the gel fractions (P = 0.0065) and more foreign particles were observed in the ejaculates (P = 0.0007) compared to male rabbits from group 2. The first week of semen collection also revealed a light intensity effect on spermatozoa obtained by swim-up procedure. The concentrations of spermatozoa from group 2 were higher than those from group 1 (P &lt; 0.0001). This effect was only slightly visible for motility after swim-up (P = 0.067).

Effect of light intensity on first feeding of the chub mackerel Scomber japonicus larvae

This study investigated the effect of different light intensities on first feeding of chub mackerel Scomber japonicus larvae. Fertilized eggs, obtained from LHRHa-induced spawning of captive broodstock, were stocked (60 larvae/l) into twelve 30-l aquaria under light intensities of 0, 100, 200, 500 and 1000 lx, with three replicate aquaria per treatment. Temperature was maintained at 20°C and salinity was 35 psu. Larvae were fed the rotifer Brachionus rotundiformis at a density of five rotifers/ml. Feeding incidence was measured as the percentage of larvae with prey in the digestive tract. Feeding intensity was evaluated as the number of prey in the digestive tract of the larvae. Larvae fed in darkness (0 lx) had significantly lower (P<0.05) feeding incidence (13±0.05% larvae with prey) and feeding intensity (1.00±0.05 rotifers per larva) than those larvae fed at 100 (30±0.07%, 1.17±0.09 rotifers per larva), 200 (43±0.08%, 1.24±0.11 rotifers larvae−1), 500 (53±0.08%, 1.48±0.14 rotifers per larva) and 1000 lx (60±0.08%, 1.38±0.13 rotifers per larva). The feeding incidence of S. japonicus larvae increased with light intensity while feeding intensity showed no significant difference (P>0.05) between light treatments.

PERBEDAAN PENGGUNAAN INTENSITAS CAHAYA LAMPU TERHADAP HASIL TANGKAPAN BAGAN APUNG DI PERAIRAN SELAT ROSENBERG KABUPATEN MALUKU TENGGARA KEPULAUAN KEI

One of potential fishing grounds for small pelagic fish in Southeast Mallucas Regency is Rosenberg Strait waters. In this region, a study on the effect of different light intensities of floating lift net on fish catches was carried out. The analyses were done on light distribution of 4 light intensities different: Petromaks Lamp and Underwater Lamps of each 18 watt, 36 watt and 54 watt. This study showed that catches of floating lift net using different light intensities were statistically significantly different. The use of 36 watt and 54 watt underwater lamp yielded the same amount of catches but higher than that of 18 watt-underwater lamp and petromaks, both in number and species. Catches consisted of 17 species, 16 fishs and 1 mollusca. Number of species and size also varied with light intensity used. There were 13 fishs species dominated by Stolephorus indicus as much as 46.9 kg or 22% for petromaks catches, 14 fishs species dominated by Rastrelliger kanagurata as much as 64 kg (31%) for 18 watt underwater lamp, 17 fishs species dominated by Rastrelliger kanagurata as much as 76 kg (28%) for 36 watt underwater lamp, and 15 fishs species dominated by Stolephorus devisi as much as 54.8 kg (22%) for 54 watt underwater lamp, respectively. Based on the results, it is recommended that the use of light intensity in fishing operations of floating lift net should be 36 watt and 54 watt underwater lamps, due to high catches, both in number and species. Beside that, since light fishing has also caught illegal fish size, number of this fishing gear type should be controlled.

Within-canopy and ozone fumigation effects on 13C and 18O in adult beech (Fagus sylvatica) trees: relation to meteorological and gas exchange parameters

In this study, the effects of different light intensities either in direct sunlight or in the shade crown of adult beech (Fagus sylvatica L.) trees on delta13C and Delta18O were determined under ambient (1 x O3) and twice-ambient (2 x O3) atmospheric ozone concentrations during two consecutive years (2003 and 2004). We analysed the isotopic composition in leaf bulk, leaf cellulose, phloem and xylem material and related the results to (a) meteorological data (air temperature, T and relative humidity, RH), (b) leaf gas exchange measurements (stomatal conductance, g(s); transpiration rate, E; and maximum photosynthetic activity, A(max)) and (c) the outcome of a steady-state evaporative enrichment model. Delta13C was significantly lower in the shade than in the sun crown in all plant materials, whilst Delta18O was increased significantly in the shade than in the sun crown in bulk material and cellulose. Elevated ozone had no effect on delta13C, although Delta18O was influenced by ozone to varied degrees during single months. We observed significant seasonal changes for both parameters, especially in 2004, and also significant differences between the study years. Relating the findings to meteorological data and gas exchange parameters, we conclude that the differences in Delta18O between the sun and the shade crown were predominantly caused by the Péclet effect. This assumption was supported by the modelled Delta18O values for leaf cellulose. It was demonstrated that independent of RH, light-dependent reduction of stomatal conductance (and thus transpiration) and of A(max) can drive the pattern of Delta18O increase with the concomitant decrease of delta13C in the shade crown. The effect of doubling ozone levels on time-integrated stomatal conductance and transpiration as indicated by the combined analysis of Delta18O and delta13C was much lower than the influence caused by the light exposure.

Modelling of hydrogen production in batch cultures of the photosynthetic bacterium Rhodobacter capsulatus

The photosynthetic bacterium, Rhodobacter capsulatus, produces hydrogen under nitrogen-limited, anaerobic, photosynthetic culture conditions, using various carbon substrates. In the present study, the relationship between light intensity and hydrogen production has been modelled in order to predict both the rate of hydrogen production and the amount of hydrogen produced at a given time during batch cultures of R. capsulatus. The experimental data were obtained by investigating the effect of different light intensities (6000–50,000 lux) on hydrogen-producing cultures of R. capsulatus grown in a batch photobioreactor, using lactate as carbon and hydrogen source. The rate of hydrogen production increased with increasing light intensity in a manner that was described by a static Baly model, modified to include the square of the light intensity. In agreement with previous studies, the kinetics of substrate utilization and growth of R. capsulatus was represented by the classical Monod or Michaelis–Menten model. When combined with a dynamic Leudekong–Piret model, the amount of hydrogen produced as a function of time was effectively predicted. These results will be useful for the automatization and control of bioprocesses for the photoproduction of hydrogen.

Effects of shade on arbuscular mycorrhizal colonization and growth of crops and tree seedlings in Central India

The study was conducted to investigate the effects of different light intensities (25, 50, 67, and 100% of full sun (open)) on arbuscular mycorrhizal (AM) colonization and growth of two intercrops (a rainy season crop, Phaseolus mungo Roxb. var. PU-35 and a winter crop, Triticum aestivum L. var. WH-147) and seedlings of two multipurpose tree species (Eucalyptus tereticornis Sm. (Clone C-7, ITC, Bha- drachalam) and Albizia procera Benth.) of Central India. The results showed that various plant growth parameters viz., shoot length, dry weight and phos- phorus (P) uptake were adversely affected by low light intensity. Inoculations with AM fungi (Acaulospora scrobiculata Trappe, Glomus intraradix Schenck & Smith and an unidentified Glomus species) increased the plant growth on account of all measured param- eters under tested light conditions. Mycorrhizal efficiency of different AM fungi varied in narrow range. AM inoculants were more efficient at higher light intensity in above mentioned plant species, except wheat. Data on colonization of P. mungo, T. aestivum, E. tereticornis and A. procera showed that formation of arbuscules, vesicles and sporocarp was delayed by lower light intensity. Colonization index of host roots and spore counts increased with increase in

Effect of Light Intensity on Live Performance and Processing Characteristics of Broilers

This study investigated the effects of different light intensities provided via an increasing photoperiod program on broiler live performance and processing characteristics. A total of 1,080 male broilers were evenly distributed in 12 rooms. Six rooms were subjected to intensities of either 15 footcandles (FC) from 1 to 51 d (Bright), or 0.5 FC from 1 to 9 d and 0.1 FC from 9 to 51 d (Dim). Both intensity treatments were provided in an increasing photoperiod program (23L:1D, 1 to 9 d; 12L:12D, 9 to 16 d; 14L:10D, 16 to 23 d; 17L:7D, 23 to 30 d; 20L:4D, 30 to 37 d; and 23L:1D, 37 to 51 d). Feed consumption and BW were determined, and feed conversions were calculated approximately weekly. Mortalities were necropsied and recorded daily. At 51 d, 30 birds from each room were processed and cut up to determine weights and yields. Beginning at 23 and 30 d, respectively, BW and feed consumption were greater in the Dim treatment. At 51 d, Dim treatment BW was 4.7% greater and feed consumption was 3.9% greater. Feed conversion, metabolic and total mortality, and BW uniformity were not influenced by light intensity. Weights of lean carcass, total breast, fillets, tenders, and legs were from 4.9 to 6.2% greater in the Dim treatment, which was proportional to the BW difference and resulted in similar yields of these parts. However, wings were 9.9% heavier in the Dim treatment, which resulted in greater wing yield. Equal fat pad weights resulted in reduced fat pad yield in the Dim treatment. These results indicate that BW, feed consumption, and most parts weights were increased proportionally by providing 0.1 vs. 15 FC of light intensity via an increasing photoperiod program, and that only the yields of minor parts were affected by intensity.

Influence of light intensity on feeding, growth, and early survival of leopard coral grouper ( Plectropomus leopardus) larvae under mass-scale rearing conditions

This study investigated the effect of different light intensities on feeding, growth and survival of early stage leopard coral grouper Plectropomus leopardus larvae. Four different light intensities (0, 500, 1000 and 3000 lx) were used and larvae were kept under constant light conditions from 0 day after hatching (DAH) to 5 DAH. The larvae were fed a small S-type of Thai strain rotifers at a density of 20 individuals/mL from 2 DAH. The number of rotifers in larval digestive organ and total length of larvae were examined at 3 h intervals between 04:00 and 22:00 h on 3 DAH, and thereafter at 6 h intervals until the end of the experiment (5 DAH). Four experimental trials of the larval rearing were repeated using by 60 kL mass-scale rearing tanks. The results indicate that coral grouper larvae are visual feeders and their food intake increases with increasing light intensity. Food intake of larvae reared at 3000 lx was significantly higher than those reared at 0–1000 lx on 3 DAH despite being the first-feeding day ( P < 0.01). On 4 DAH, total length of larvae reared at 3000 lx was significantly larger than those reared at the lower light intensities (0, 500 and 1000 lx), and thereafter light intensity significantly influenced larval feeding and growth until the end of the experiment. Survival on 5 DAH did not show a significant difference between light intensities, but survival rate at 3000 lx and 1000 lx had a tendency to be higher than those reared at the lower light intensities (0 and 500 lx). In contrast, larvae reared at 0 lx exhibited stagnant and/or negative growth. These results indicate that light intensity is significantly the factor affecting larval feeding, growth, and survival in coral grouper larvae under the rearing conditions.

Growth, photosynthesis and stress indicators in young rosewood plants (Aniba rosaeodora Ducke) under different light intensities

Aniba rosaeodora is an Amazonian tree species that belongs to the family Lauraceae. Due to intense exploitation for extraction of essential oils (mainly linalol), A. rosaeodora is now considered an endangered species. On the other hand, there is little information about its ecophysiology which would be useful to support future forest planting programs. Hence, the effect of different light intensities on the growth and photosynthetic characteristics of young plants of A. rosaeodora was studied. Nine-month-old plants were subjected to four light treatments (T1= 10 a 250 µmol.m-2.s-1 / control; T2=500 to 800, T3=700 to 1000 and T4=1300 to 1800 µmol.m-2.s-1 / full sunlight). Allometric variables, gas exchange, contents of pigments and chlorophyll a fluorescence were analysed. As to the relative growth rates, it was found that plants of A. rosaeodora showed higher biomass accumulation when grown under intermediary irradiance conditions (T2). The best photosynthetic performance was achieved under conditions of T3. When growth was correlated with photosynthesis, it was found that plants under treatments T2 and T3 presented better responses in comparison with the lowest (T1) and highest (T4) light extremes. The highest pigment contents were obtained for plants in the shade (T1) and the lowest for those exposed to full sunlight (T4). The photochemical efficiency of photosystem II (Fv/Fm) was found that only plants in the shade treatment (T1) presented no stress from high irradiance. These findings suggest that both treatments (T1 and T4) altered the function of the A. rosaeodora plants, inhibiting photosynthesis and growth. Plants of A. rosaeodora developed photo-protection mechanisms under full sunlight. However, the species presented better photosynthetic response and biomass gain under intermediary irradiance conditions, displaying relative physiological plasticity, during the seedling phase.

The effect of light intensity on early life development of common dentexDentex dentex(L. 1758) larvae

The effects of different levels of illumination on common dentex Dentex dentex (L.) larvae have been examined. Illumination affected the relationships between total length and digestive tube length, total length and oil globule volume, and total length and yolk sac. The relationship between total length development and yolk sac utilization in dark and light conditions was found to be significant (P 0.05). Besides, there is no effect of different light intensities on absorption of yolk sac and oil globule and digestive tube development (P>0.05). In addition, total length development was not significant (P>0.05). Survival rate was found to be not significantly different in dark conditions (P>0.05).

Fischer 344 and Wistar Rats Differ in Anxiety and Habituation but Not in Water Maze Performance

The fact that various neuropharmacological substances have anxiolytic as well as amnesic effects suggests that neuronal mechanisms of anxiety and learning/memory closely interact. Hence, we hypothesized that differences in anxiety-related behavior could be accompanied with differences in cognition or habituation. Two rat strains with different levels of anxiety, more anxious Fischer 344 rats by Charles River (FC) and less anxious Wistar rats by Winkelmann (WW), were tested in the Morris water maze task and an open field test for habituation learning. Additionally, we investigated the effect of different light intensities on the performance in the Morris water maze and the elevated plus maze. The results of the water maze task indicate that differences in anxiety-related behavior do not go along with differences in this performance of learning/memory. Moreover, the test was not affected by different light intensities. In contrast, illumination did affect performance in the elevated plus maze test, wherein dim light provoked an anxiolytic effect in both rat strains. The findings that neither different baseline levels of anxiety nor fear modulating light conditions were accompanied by changes in the performance of rats in the Morris water maze led us to the suggestion that there is no connection between anxiety and learning/memory in this task. Contrarily, anxiety might be associated with habituation learning in the open field test, shown by the superior habituation of the anxious FC rats in comparison to the less anxious WW rats. In sum, these results indicate that anxiety and learning/memory seem to be independently regulated behaviors, whereas habituation might be more closely correlated with anxiety. Nevertheless, a general statement about the relation between emotionality and learning/memory mechanisms would be premature and the link between behaviors remains to be clarified.

Solar Photocatalytic Destruction of p-Nitrophenol: A Pedagogical Use of Lab Wastes

In this article we propose the destruction of p-nitrophenol wastes obtained in a previous lab experiment, to generate a new lab experiment. The recommended destruction technique is solar TiO2-photocatalysis. When the effects of TiO2 and sunlight are tested separately, a slight decrease of p-nitrophenol is observed; but when TiO2 and sunlight are employed together p-nitrophenol disappears in 1 or 2 h. These experiments do not require sophisticated equipment or special lab training for the students. Groups of students tested different experimental conditions, such as the effect of different light intensities and sources (800-W UV-lamp, sunlight on sunny days, and sunlight on a cloudy day) or the addition of H2O2. p-Nitrophenol is degraded under the three light sources but at different rates. The addition of H2O2 to the TiO2-plus-sunlight system enhances p-nitrophenol degradation kinetics when compared with the TiO2 plus sunlight and H2O2 plus sunlight combinations.

The Influence of the Bright Light Exposure during Daytime on Melatonin Excreting Rate in Urine

The present study was conducted to know the effects of different light intensities exposed during daytime for several hours on melatonin excreting rate in urine and tympanic temperature. Eleven healthy female subjects were exposed to bright light of 6000 lx (Bright) or dim light of 100 lx (Dim) during daytime from 09:00 h to 13:30 h, and then the light condition was kept at 100 lx until the end of test at 14:30 h. The urinary samples were collected from 10:00 h to 14:30 h every 1.5 hours, and melatonin excreting rate in urine was measured by enzyme immunoassay. Melatonin excreting rate in urine was significantly higher in Bright than in Dim at 11:30 h and 14:30 h, and not significant but at high level at 13:00 h (p <0.07). Moreover, average tympanic temperatures were significantly lower in Bright than in Dim from 11:43 h to 14:30 h. These results showed that the bright light exposure during daytime could reduce tympanic temperature, which might result from the increase of melatonin level.

Light and storage on the germination of spores of Dicksonia sellowiana (Presl.) Hook., Dicksoniaceae

Spores of Dicksonia sellowiana are positively photoblastic and reach the maximum percentage of germination at 23 ± 2°C in white light after seven days of imbibition. The pre-induction phase for spores induced by white or red light for 24 hours was 72 hours. Gametophytes grown in white light were plane and bidimensional, while those grown under red light were filamentous. The higher the number of hours of light applied per day during 10 days, the higher the percentage of germination. Germination was higher for long white light treatments applied on a daily basis. The effect of different light intensities on germination was also investigated here. The lower percentages of germination were observed for spores kept under 43% and 2% of full sunlight, while those kept under 26, 19 and 4% presented higher percentages. Spores presented circa 82% of germination after 731 days of storage under refrigeration at aproximately 10°C.

Effects of different light intensities during the daytime on circadian rhythm of core temperature in humans.

The present study was to determine the effects of bright light exposure during the daytime on core temperature rhythm. Eight female students participated as subjects. They were exposed to bright light of 5000 lux or dim light of 200 lux for 13 hours (06:30-19:30) for two consecutive days. Except the sleep period (22:30-06:30) and during the bright light exposure, light intensity was controlled at 200 lux. Rectal temperature data were collected every 10 min throughout the whole experimental period. The mean level of rectal temperature was not significantly different between the bright and the dim light conditions. However, the evening fall and the morning rise of rectal temperature were significantly greater in the bright light conditions on Day 2 compared to the dim. Furthermore, cosinor analysis showed that the acrophase of rectal temperature rhythm was earlier on Day 2 in the bright light conditions than the dim, and was significantly delayed on Day 2 compared to Day 1 in the dim light conditions. These results suggest that low intensity during the daytime for two consecutive days may induce a phase delay of core temperature rhythm rather than the bright light exposure at least in normally entrained female subjects.