Full Light Intensity Research Articles

Light stress elicits soilborne disease suppression mediated by root-secreted flavonoids in Panax notoginseng.

Developing disease-suppressive soils is an effective approach for managing soilborne diseases, which can be achieved through crop metabolism and root secretion modification to recruit beneficial soil microbiota. Many factors, such as light, can elicit and modify plant metabolomic activities, resulting in disease suppression. To investigate the impact of light, Panax notoginseng was planted in a greenhouse and forest, conditioned with three levels of light intensities, including the optimal (15% light transmittance of full light), suboptimal low (5% light transmittance of full light) and suboptimal high (30% light transmittance of full light) intensities. We assessed the rhizosphere microbiota of P. notoginseng and root rot disease caused by soilborne pathogen Ilyonectria destructans, and elucidated the mechanism. Results showed that suboptimal light conditions alleviated root rot disease of P. notoginseng by enriching beneficial microbiota in the rhizosphere. Both low and high light stresses enhanced the secondary metabolism profile in favor of plant defense, particularly the flavonoid pathway. Notably, high light stress demonstrated a robust ability to promote flavonoid metabolism and secretion, resulting in the enrichment of more beneficial microorganisms that suppressed the soilborne pathogen I. destructans. These findings highlight the potential for adjusting canopy light intensities to improve soil health and promote sustainable agriculture.

Phytochemical compositions and antioxidant activity of green and purple basils altered by light intensity and harvesting time

Ocimum basilicum L. is one of the most important medicinal and vegetable crops due to its essential oil, pleasant aroma and taste. In this study, we evaluated the impact of different light intensities, including 100 %, 50 %, and 30 % of natural sunlight, on the growth, phytochemical compositions, and antioxidant activity of green and purple basil cultivars at two different harvest times: early morning and noon. The height of the plant, number of leaves per plant, length of the petiole, diameter of the stem, and fresh and dry weight of the shoot were all reduced by decreasing light intensity in both basil cultivars. When the plants of both cultivars were grown under full light intensity and were sampled at noon, they showed the highest phenolic and flavonoid contents. The highest antioxidant activity was detected in purple basil cultivars grown under 30 and 50 % of sunlight in both harvests. The green basil cultivar showed the highest antioxidant activity when exposed to 30 % sunlight and harvested in the early morning. The highest essential oil content and yield in both basil cultivars were obtained under full sunlight in the early morning harvests. In summary, light intensity and harvest time influence the phytochemical yield, composition, and growth of two studied basil cultivars. Optimal results, particularly for medicinal purposes, were achieved by morning harvesting to maximize the essential oil yield of basils.

Physiological and Structural Changes in Leaves of Platycrater arguta Seedlings Exposed to Increasing Light Intensities.

Understanding the light adaptation of plants is critical for conservation. Platycrater arguta, an endangered deciduous shrub endemic to East Asia, possesses high ornamental and phylogeographic value. However, the weak environmental adaptability of P. arguta species has limited its general growth and conservation. To obtain a deeper understanding of the P. arguta growth conditions, we examined the leaf morphology and physiology via anatomical and chloroplast ultrastructural analyses following exposure to different natural light intensities (full light, 40%, and 10%). The findings indicated that P. arguta seedings in the 10% light intensity had significantly improved leaf morphological characteristics and specific leaf area compared to those exposed to other intensities. The net photosynthetic rate, chlorophyll (Chl) content, photosynthetic nitrogen use efficiency (PNUE), and photosynthetic phosphorus use efficiency (PPUE) exhibited marked increases at a 10% light intensity compared to both 40% light and full light intensities, whereas the light compensation point and dark respiration levels reached their lowest values under the 10% light condition. With reduced light, leaf thickness, palisade tissue, spongy tissue, and stomatal density significantly decreased, whereas the stomatal length, stomatal width, and stomatal aperture were significantly elevated. When exposed to 10% light intensity, the ultrastructure of chloroplasts was well developed, chloroplasts and starch grain size, the number of grana, and thylakoids all increased significantly, while the number of plastoglobules was significantly reduced. Relative distance phenotypic plasticity index analysis exhibited that P. arguta adapts to varying light environments predominantly by adjusting PPUE, Chl b, PNUE, chloroplast area, and the activity of PSII reaction centers. We proposed that P. arguta efficiently utilizes low light to reconfigure its energy metabolism by regulating its leaf structure, photosynthetic capacity, nutrient use efficiency, and chloroplast development.

Foliar applied titanium dioxide nanoparticles (TiO2 NPs) modulate growth, physiological and phytochemical traits in Melissa officinalis L. under various light intensities

Lemon balm (Melissa officinalis L.) is a valuable medicinal plant belonging to the mint family Lamiaceae with different uses in the food, cosmetic-hygienic, and pharmaceutical industries. Therefore, it is crucial to identify novel factors affecting growth, yield, and phytochemical compounds of this plant. In the current study, titanium dioxide (TiO2) nanoparticles (NPs) were foliarly applied at different concentrations (0, 50, and 100 mg L−1) following various light intensities (full (control), 75% and 50% sunlight) on lemon balm in a factorial experiment based on randomized complete block design (RCBD) with three replications (n = 3) for two continues years. IAnalytical techniques, SEM and EDX analyses, confirmed the uptake of TiO2 NPs through aerial parts of plant. Output of shoot dry weight, chlorophyll a (Chl-a) content, and total Chl and relative water content (RWC) were at their highest levels on plants grown at 50% light intensity upon foliar application of TiO2 NPs (100 mg L−1) in both years. High shading (50% of light intensity) without TiO2 NPs application markedly reduced EO content (by 60%), when compared to full solar radiation and exposure to TiO2 NPs (at 50 and 100 mg L−1) during two experimental years. Neral and geranial were the two main components of EO, with 30.7% and 45.05% in the first year of experiment, followed by 30.24% and 43.03% in full light intensity under 100 mg L−1 TiO2 NPs applications in the second year, respectively. Thus, a relatively shady environment and 100 mg L−1 TiO2 NPs foliar spray are recommended to attain a higher yield in lemon balm plants. Key findings of this study revealed the beneficial effects of high light intensity with TiO2 NPs foliar spray to improve the quality and quantity output of EO rich in neral and geranial constituents.

Natural Regeneration of Morus alba in Robinia pseudoacacia Plantation and the Mechanism of Seed Germination and Early Seedling Growth Restriction in the Yellow River Delta

There is a wide range of naturally regenerated Morus alba in the declining Robinia pseudoacacia plantation of the Yellow River Delta. It is important to clarify the key mechanism of natural regeneration of M. alba for the transformation of declining R. pseudoacacia plantation. According to the death density of R. pseudoacacia, the plantation of R. pseudoacacia was divided into nondeclining, moderately declining, and severely declining forests. The structural characteristics of adult trees and seedlings of M. alba in different decline degrees forest were investigated. A pot experiment was conducted to study the seed germination and early seedling growth of M. alba in saline alkali soil and nonsaline alkali soil under different soil salt contents and light intensities. The results showed that the natural regeneration of M. alba was obviously affected by the decline of R. pseudoacacia plantation. With the increase of decline degree, M. alba density and seedling density first increased and then decreased, and were the highest in the medium decline plantation. Under full light intensity, the vigor index of M. alba seeds and the biomass of seedlings were significantly greater than those of 25% full light intensity. The germination rate and germination index under 1‰ soil salt content were significantly lower than those under 3‰, but the biomass of seedlings was on the contrary. The 1000-seed weight, seed germination, and seedling biomass of moderately declining R. pseudoacacia plantations were close to those of nonsaline alkali land, while significantly higher than those of nondeclining plantations, but the germination index of moderately declining R. pseudoacacia plantation was higher than that of nonsaline alkali land. Therefore, the germination ability of maternal trees in saline alkali land was higher than that in nonsaline alkali land under salt stress.

Spin‐Selective Full and Subtle Light Intensity Manipulation with Diatomic Metasurfaces

AbstractMetasurfaces are considered to be ideal candidates for precise and continuous manipulation of optical wave intensity at nanoscale pixels, which is the main basis of display and imaging devices. Malus's law has been widely used as the basic design principle for the realization of linearly polarized optical wave intensity manipulation. However, there is no such straightforward and concise law like Malus's law that can be used to design metasurfaces for full and subtle intensity manipulation of circularly polarized optical waves. Here, a new design strategy based on the collective interference effect in diatomic metasurfaces is presented to fill this gap, which can create a simple and complete mapping from a single structural variable to the reflection intensity of circularly polarized waves. The full and subtle intensity manipulation of circularly polarized optical waves can be conveniently realized by changing one structural parameter in the diatomic metasurface. Spin‐selective high‐level grayscale images are numerically and experimentally implemented based on the proposed diatomic metasurfaces. The proposed grayscale imaging scheme with subwavelength spatial resolution and high gray level is promising for advanced display and information encryption applications.

Chemical Synthesis of Bismuth Oxide and Its Ionic Conversion to Bismuth Sulphide for Enhanced Electrochemical Supercapacitor Energy Storage Performance

Successive ionic layer adsorption and reaction (SILAR)-based room-temperature (27 °C) chemical synthesis of bismuth oxide (Bi2O3) and its ionic conversion to bismuth sulphide (Bi2S3) has been performed and reported in the present study. A chemical conversion of the bismuth oxide to the bismuth sulphide has been confirmed using changes in the structure, phase, surface elementals , and surface area measurement studies. Both bismuth oxide and bismuth sulphide electrode materials are envisaged in electrochemical measurements wherein, the later has evidenced an enhanced electrochemical performance over the prior. The cycling stability of the Bi2S3 (91% after 2000 cycles) electrode material is also better than the Bi2O3 (87% over 2000 cycles). The as-assembled Bi2S3//Bi2S3 symmetric electrochemical supercapacitor device has adduced 75.3 Wh kg−1 and 749.8 W Kg−1energy and power densities, respectively with nearly 88.8% capacitance retention efficacy even over 2000 redox cycles measured at 10 A g−1. The commercial potential of the Bi2S3//Bi2S3 has been tested by powering the display panel “CNED” consisting nearly 42 LEDs with a full-light intensity.

Physiological responses of cowpea simultaneously exposed to water deficit stress and varying light intensities at vegetative and reproductive growth stages

A combination of stresses as it occurs on the field poses more challenges to crop production than individual stress. Crops’ response to single stress also differs from that of combined stresses. The morpho-physiological responses of two cowpea varieties (IT89KD-288 and IT99K573-1-1) to a combination of stresses (water deficit stress and high light intensity) were investigated at different growth stages. Three levels of light intensities (L3: 259 Lux- 36%, L2: 394 Lux-55% and L1: 710.2 Lux-100%) were imposed using one, two and zero layer(s) of the net, respectively, while, water deficit stress at four levels (W1: no water stress; 0-5 bars, W2: moderate water stress; 5-15 bars, W3: moderately-severe; 15-40 bars and W4: severe water stress; 40 -70 bars) was imposed differently at vegetative and reproductive growth stages. Data were collected on the cowpea yield, Leaf Temperature (LT), Chlorophyll (C), Photosynthesis (P), Stomatal Conductance (SC) and Canopy Transpiration Rate (CTR). Exposure to W4 under L1 considerably reduced cowpea yield by 80% compared to those grown under L3 and full watering. Reduced light intensity enhanced cowpea grain yield irrespective of water deficit stress and IT89KD-288 was superior to IT99K573-1-1. Reduction in light intensity also increased the SC from 55.18 in L1 to 76.88 in 36 % L3. Full light intensity without water stress (100% light intensity), increased C content, while severe water stress reduced the C content and CTR. Photosynthesis was, however, reduced under low light intensity compared to 100% light intensity. It was also observed that water deficit stress imposed at the reproductive stage did not affect P, CTR and SC unlike that of the vegetative stage. In conclusion, reduced light intensity enhanced cowpea tolerance to water deficit and increased yield. Cowpea response was dependent on growth stage, variety and severity of stress.

Responses of purple rice variety to light intensities and soil zinc application on plant growth, yield and bioactive compounds synthesis

Low light intensity restricts rice productivity, however, no deep information is evaluated on purple rice production and its bioactive compound. This study investigated the effects of light intensity on plant growth, yield, and bioactive compounds synthesis during the vegetative (experiment 1) and reproductive (experiment 2) stages of purple rice varieties grown with and without zinc fertilizer application. At the seedling stage in experiment 1, low and intermediate light intensities significantly decreased the total dry weight by 31% and 63%, respectively, compared with the full light intensity. The lower light intensity also decreased the concentrations of seedling total anthocyanin by 81% and total phenol by 36% compared to the full light intensity. At the reproductive stage in experiment 2, shading at early and seed development stages decreased grain yield by 15% compared to the unshaded grains. The concentrations of total anthocyanin and total phenol, DPPH activity, and anthocyanin compounds were increased by shading, while phenolic acid and flavonoid compounds were fluctuated depending on the compound species. Applying soil zinc fertilizer produced no significant improvement in productivity or bioactive compounds but did increase grain zinc concentration by from 6% to 13% compared to zero zinc application. These results will be useful for improving grain yield and quality in purple rice cultivation during the rainy season.

Brain trauma impacts retinal processing: photoreceptor pathway interactions in traumatic light sensitivity

BackgroundConcussion-induced light sensitivity, or traumatic photalgia, is a lifelong debilitating problem for upwards of 50% of mild traumatic brain injury (mTBI) cases, though of unknown etiology. We employed spectral analysis of electroretinographic (ERG) responses to assess retinal changes in mTBI as a function of the degree of photalgia.MethodsThe design was a case–control study of the changes in the ERG waveform as a function of level of light sensitivity in individuals who had suffered incidents of mild traumatic brain injury. The mTBI participants were categorized into non-, mild-, and severe-photalgic groups based on their spectral nociophysical settings. Light-adapted ERG responses were recorded from each eye for 200 ms on–off stimulation of three spectral colors (R:red, G:green, and B:blue) and their sum (W:white) at the highest pain-free intensity level for each participant. The requirement of controls for testing hypersensitive individuals at lower light levels was addressed by recording a full light intensity series in the control group.ResultsBoth the b-wave and the photopic negative response (PhNR) were significantly reduced in the non-photalgic mTBI group relative to controls. In the photalgic groups, the main b-wave peak shifted to the timing of the rod b-wave, with reduced amplitude at the timing of the cone response.ConclusionThese results suggest the interpretation that the primary etiology of the painful light sensitivity in mTBI is release of the rod pathway from cone-mediated inhibition at high light levels, causing overactivation of the rod pathway.

Seed germination ecology of Sumatran fleabane (Conyza sumatrensis) in relations to various environmental parameters

AbstractSumatran fleabane [Conyza sumatrensis (Retz.) Walker] is an emerging weed in the Australian cropping region. Populations resistant to glyphosate have evolved in Australia, creating the demand for information regarding the seed germination ecology of glyphosate-resistant (R) and glyphosate-susceptible (S) populations of C. sumatrensis. A study was conducted to examine the effects of temperature, light intensity, salt stress, osmotic stress, and burial depth on the germination and emergence of two populations (R and S) of C. sumatrensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C). In light/dark conditions, the R population had higher germination than the S population at 20/10 and 35/25 C. In the dark, the R population had higher germination than the S population at 25/15 C. In the dark, germination was inhibited at 30/20 C and above. Averaged over populations, seed germination of C. sumatrensis was reduced by 97% at zero light intensity (completely dark conditions) compared with full light intensity. Seed germination of C. sumatrensis was reduced by 17% and 85% at osmotic potentials of −0.4, and −0.8 MPa, respectively, compared with the control treatment. The R population had lower germination (57%) than the S population (72%) at a sodium chloride concentration of 80 mM. Seed germination was highest on the soil surface and emergence was reduced by 87% and 90% at burial depths of 0.5 and 1.0 cm, respectively. Knowledge gained from this study suggests that a shallow-tillage operation to bury weed seeds in conventional tillage systems and retention of high residue cover on the soil surface in zero-till systems may inhibit the germination of C. sumatrensis. This study also warrants that the R population may have a greater risk of invasion over a greater part of a year due to germination over a broader temperature range.

Response of Red Maple (Acer rubrum L.) Micropropagation to Different In Vitro Conditions

A reliable micropropagation protocol was developed for Red Maple tree for the first time in Iraqi Kurdistan Region to introduce this newly entered species to the local community. At initiation stage, healthy and vigorous cultures were established following a critical disinfestation protocol by bleach (Sodium hypochlorite) at 2.5 % for 20 minutes. The obtained results show that shoots multiplication was successfully enhanced by recording the highest number of shoots and leaves per explant when 0.5 mg.L-l BA was added to WPM by recording 2.08 shoots/ explant and 13.7 leaves/ explant, respectively. Whereas, the longest shoots were obtained when 1.5 mg.L-l BA was added by reaching 1.86 cm. For root formation, IBA was more effective than NAA by giving the best rooting parameters. The highest number of roots per explant (3.00 roots/ explant), the longest roots (5.87 cm) and the highest rooting percentage (100%) were obtained when 0.1 mg.L-l IBA was added to WPM. The half-light intensity (50 feet/ candle) showed better rooting abilities of microshoots than full light intensity conditions (100 feet/ candle) by raising the number of roots from 3.00 to 4.00 roots/ explants, increasing the mean length of roots from 5.87 cm to 6.37 cm when the comparing between the highest rooting parameters at full light illumination. A 100% survival rate was achieved from the acclimatized plantlets in the greenhouse conditions without any abnormal morphological characteristics. It can be recommended that this important plant can be propagated by tissue culture technique toward mass production in the local area.

Plasticity of Leaf Traits of Juglans regia L. f. luodianense Liu et Xu Seedlings Under Different Light Conditions in Karst Habitats

This study examined the effects of light intensity on the plasticity of the leaves of Juglans regia f. luodianense seedlings in karst habitat and how they respond to changes in light intensity. The light intensity of 1-year-old seedlings of J. regia f. luodianense in different niches in a karst area was set as 100% (bare land), 75% (forest margin), 50% (forest gap), and 25% (under forest) of natural light. The material harvested after four months was compared to analyze the differences in various morphological characteristics, biomass allocation, and physiological characteristics of the leaves of seedlings of J. regia f. luodianense, and a comprehensive evaluation of the plasticity indexes was conducted. The results showed that under moderate (50%) full light intensity, the leaf area, specific leaf area, leaf biomass, and chlorophyll content increased, and improved photosynthesis and promoted the accumulation of free proline content and peroxidase (POD) activity. The accumulation of malondialdehyde was also the lowest in this treatment, indicating that the plants had the strongest adaptability under this light intensity. Moreover, under high (75%) full light intensity, the above functional characteristics of plants showed good performance. Under low (25%) full light intensity, plants also had higher specific leaf area, leaf biomass, and photosynthetic parameters. However, under full light, the cell membrane permeability decreased, the chlorophyll accumulation was the lowest, and the photosynthetic index was seriously inhibited. Our results showed that the plasticity of morphological characters was greater than that of biomass allocation and physiological characters; POD activity and stomatal conductance were the highest, followed by leaf area and chlorophyll b, whereas the plasticity of palisade tissue/sponge tissue thickness and lower-epidermis thickness were the lowest. In summary, there are evident differences in the sensitivity and regulation mechanisms of morphological characteristics, biomass allocation, and physiological indices of the seedling leaves of J. regia f. luodianense in response to light intensity. During the stage of seedling establishment, only the plants in the bare ground under full light can be induced to show obvious inhibition of phenotypic traits. In contrast, the plants in the forest margins and gaps and under the forest habitats under light intensity can regulate their own characteristics to maintain their growth and development. The wide light range and strong plasticity of the species might be two of the important reasons for its existence in a highly heterogeneous karst habitat.

Morphological and Physiological Responses of Indigofera tinctoria L. to Light Intensity

Synthetic dyes can cause health and environmental impacts. Thus, there are opportunities to develop natural dyes, one of which is produced by Indigofera tinctoria plants. This plant is from Fabaceae that has the potential to produce a natural blue color. Natural dyes are extracted from the leaves of plants that contain indigo compounds. Indigo growth and precursors are very dependent on environmental conditions, one of which is light intensity. This study aimed to study the morphological and physiological plant responses in I. tinctoria to several levels of light intensity. The research was conducted in Puron Village, Sukoharjo, Indonesia with a complete randomized block design (RCBD) one factor, namely the level of light intensity (100 %, 50 %, and 25 %) with nine replications. Light intensity affected the morphology and physiology of I. tinctoria. Plants responded to low light intensity by increasing the leaf area index, specific leaf area and plant height. Leaf area, specific leaf area and plant height were highest at 25 % intensity. However, the number of leaves and nodes got greater at full light intensity. Higher light intensity increased the chlorophyll content a, b and total, thus, higher biomass yield which was 18.86 g at the age of 8 wk.

Minimizing scattering-induced phase errors in differential interference contrast microscopy.

.Significance: Differential interference contrast (DIC) microscopes allow noninvasive in vivo observation of transparent microstructures in tissue without the use of fluorescent dyes or genetic modification. We show how to modify a DIC microscope to measure the sample phase distribution accurately and in real-time even deep inside sample tissue.Aim: Our aim is to improve the DIC microscope’s phase measurement to remove the phase bias that occurs in the presence of strong scattering.Approach: A quarter-wave plate was added in front of the polarization camera, allowing a modified phase calculation to incorporate all four polarization orientation angles (0 deg, 45 deg, 90 deg, and 135 deg) captured simultaneously by the polarization camera, followed by deconvolution.Results: We confirm that the proposed method reduces phase measurement error in the presence of scattering and demonstrate the method using in vivo imaging of a beating heart inside a medaka egg and the whole-body blood circulation in a young medaka fish.Conclusions: Modifying a polarization-camera DIC microscope with a quarter-wave plate allows users to image deep inside samples without phase bias due to scattering effects.

Light intensity affects capsaicinoid accumulation in hot pepper (Capsicum chinense Jacq.) cultivars

Strong light intensity affects plant growth, fruit yield, and accumulation of capsaicinoids in hot peppers (Capsicum spp.) which are important food and medicinal products. Shading improves plant growth and fruit yield in bell pepper (Capsicum annuum), but research on the effect of shading on high pungency C. chinense cultivars is limited. This study investigated the responses of C. chinense cultivars to different light intensities to maximize capsaicinoid production. An experiment to test the effect of shading, i.e., no-shading (full light intensity as control), 50% shade and 70% shade of full light intensity, was conducted in a plastic-net house using four C. chinense cultivars with different pungency levels: Bhut Jolokia, Akanee Pirote, Orange Habanero, and BGH1719. The cultivars showed different capsaicinoid production levels depending on the shade level. The highest capsaicinoid yields were found in the F1 hybrid cultivar Akanee Pirote under 50% shading (4,820 mg/plant) and in the Bhut Jolokia cultivar under 70% shading (3,419 mg/plant). By contrast, the BGH1719 plants showed the lowest capsaicinoid production (291 mg/plant) when shade was applied. These results demonstrate that capsaicinoid production in the studied cultivars is affected by light intensity. It is recommended that growers of high pungency cultivars use the appropriate level of shading for the particular cultivar to increase capsaicinoid yield.

Duration and intensity of shade differentially affects mycorrhizal growth- and phosphorus uptake responses of Medicago truncatula.

Plant and fungal partners in arbuscular mycorrhizal symbiosis trade mineral nutrients for carbon, with the outcome of this relationship for plant growth and nutrition being highly context-dependent and changing with the availability of resources as well as with the specific requirements of the different partners. Here we studied how the model legume Medicago truncatula, inoculated or not with a mycorrhizal fungus Rhizophagus irregularis, responded to a gradient of light intensities applied over different periods of time, in terms of growth, phosphorus nutrition and the levels of root colonization by the mycorrhizal fungus. Short-term (6 d) shading, depending on its intensity, resulted in a rapid decline of phosphorus uptake to the shoots of mycorrhizal plants and simultaneous accumulation of phosphorus in the roots (most likely in the fungal tissues), as compared to the non-mycorrhizal controls. There was, however, no significant change in the levels of mycorrhizal colonization of roots due to short-term shading. Long-term (38 d) shading, depending on its intensity, provoked a multitude of plant compensatory mechanisms, which were further boosted by the mycorrhizal symbiosis. Mycorrhizal growth- and phosphorus uptake benefits, however, vanished at 10% of the full light intensity applied over a long-term. Levels of root colonization by the mycorrhizal fungus were significantly reduced by long-term shading. Our results indicate that even short periods of shade could have important consequences for the functioning of mycorrhizal symbiosis in terms of phosphorus transfer between the fungus and the plants, without any apparent changes in root colonization parameters or mycorrhizal growth response, and call for more focused research on temporal dynamics of mycorrhizal functioning under changing environmental conditions.

Forage and seed production of Puero (Pueraria javanica) in a different light intensity level

Puero ( Pueraria javanica ) is forage that can serve as a cover crop in plantations. The limiting factor for plant growth in the plantation is the light intensity, therefore the influence of light intensity on forage and seed production of Puero needs to be examined. Research was conducted at Kaum Pandak Research station of Indonesian Research Institute for Animal Production Bogor and Laboratory of Agrostology Faculty of Animal Husbandry, Bogor Agricultural University, for 16 months. Four levels of light intensity,i.e 100, 80,60 and 40% were applied, leguminosainous species Puero ( Pueraria javanica ), was used. The treatments were arangged in Randomized Complete Block Design with 3 replications. Data collected were analyzed by ANOVA and Duncan’s Multiple Range Test. Forage production was evaluated in one year. The forage quality and digestibility ( invitro ) were assessed. Seed production was recorded accumulatively from seasonal seed production during one year. Results show that light intensity affected (P 0.05) quality and digestibility of Puero. The highest forage and seed production of Puero were obtained from full light intensity (100%). and seed production of Puero was affected (P < 0.05) by light intensity. The seed quality of Puero was also affected by light intensity. The best seed quality of Puero was achieved by from 80% light intensity. Key Words : Light Intensity, Forage Production, Seed, Puero

Using electroretinograms to assess flicker fusion frequency in domestic hens Gallus gallus domesticus

The assessment of flicker fusion frequency (FFF), the stimulus frequency at which a flickering light stimulus can no longer be resolved and appears continuous, and critical flicker fusion frequency (CFF; the highest frequency at any light intensity that an observer can resolve flicker) are useful methods for comparing temporal resolution capabilities between animals. Behavioural experiments have found that average CFFs in domestic chickens (Gallus gallus domesticus) are in the range of ca. 75–87Hz, measured in response to full spectrum (i.e. white light plus UV) stimuli. In order to examine whether the chicken retina is able to detect flicker at higher frequencies, we used electroretinograms (ERGs) to assess FFF/CFF in adult hens from two commercial genotypes, Lohmann Selected Leghorns (LSLs) and Lohmann Browns (LBs). ERGs were recorded in response to flickering light at ten full spectrum light intensities ranging from 0.7 to 2740cdm−2. Two methods were used to determine FFF/CFF from the ERG recordings and these methods yielded very similar results, with average FFF ranging from ca. 20Hz at 0.7cdm−2 to an average CFF of ca. 105Hz at 2740cdm−2. In some individuals, CFFs of 118–119Hz were recorded. The Intensity/FFF (I/FFF) curves are double-branched with a break point representing the rod-cone transition occurring between 2.5 and 5.9cdm−2. No significant differences in the I/FFF curves were found between the two genotypes. At stimulus light intensities >250cdm−2, the ERG-derived FFF and CFF values are all higher than those from behavioural studies using the same stimuli. Although hens do not appear to be able to consciously perceive flicker above approximately 90Hz, the finding that the ERG responses are able to remain in phase with light flickering at frequencies >100Hz means that the retinae of domestic poultry housed in artificial light conditions may be able to resolve flicker from fluorescent lamps. As range of detrimental effects have been reported in humans as a result of exposure to such “invisible flicker”, the possibility exists that flicker from fluorescent lamps also acts as stressor in domesticated birds.

Behavioural assessment of flicker fusion frequency in chicken Gallus gallus domesticus

To interact with its visual environment, an organism needs to perceive objects in both space and time. High temporal resolution is hence important to the fitness of diurnally active animals, not least highly active aerial species such as birds. However, temporal resolution, as assessed by flicker fusion frequency (FFF; the stimulus frequency at which a flickering light stimulus can no longer be resolved and appears continuous) or critical flicker fusion frequency (CFF; the highest flicker fusion frequency at any light intensity) has rarely been assessed in birds. In order to further our understanding of temporal resolution as a function of light intensity in birds we used behavioural experiments with domestic chickens ( Gallus gallus domesticus) from an old game breed ‘Gammalsvensk dvärghöna’ (which is morphologically and behaviourally similar to the wildtype ancestor, the red jungle fowl, G. gallus), to generate an ‘Intensity/FFF curve’ (I/FFF curve) across full spectrum light intensities ranging from 0.2 to 2812 cd m −2. The I/FFF curve is double-branched, resembling that of other chordates with a duplex retina of both rods and cones. Assuming that the branches represent rod and cone mediated responses respectively, the break point between them places the transition between scotopic and photopic vision at between 0.8 and 1.9 cd m −2. Average FFF ranged from 19.8 Hz at the lowest light intensity to a CFF 87.0 Hz at 1375 cd m −2. FFF dropped slightly at the highest light intensity. There was some individual variation with certain birds displaying CFFs of 90–100 Hz. The FFF values demonstrated by this non-selected breed appear to be considerably higher than other behaviourally derived FFF values for similar stimuli reported for white and brown commercial laying hens, indicating that the domestication process might have influenced temporal resolution in chicken.