Continuous Incandescent Light Research Articles

The Effects of Conditioning Strawberry Plug Plants under Altered Red/Far-red Light Environments

The effect of altered red/far-red light environment on subsequent field performance of strawberry plug plants was tested. Two wavelength-selective plastic films were compared to neutral shade and full-sun control for conditioning `Chandler' strawberry plug plants before transplanting to a winter production system. The following year, plug plants of `Chandler', `Sweet Charlie', and `Allstar' were conditioned under the same treatments, with the addition of a continuous incandescent light and a short-day photoperiod, and plant performance was followed in the winter production system in Florida, a cold-climate annual hill system in Maryland, and in a low-input greenhouse production system. During the first year, the red light-filtering film slightly advanced fruiting in Florida. However, during the second year, the effect of the red light-filtering film was not significant, and a short-day treatment resulted in a greater reduction in runnering and increased early crown and flower development. For June-bearing strawberry plants maintained above 20 °C, altering the red/far-red environment did not consistently advance flowering.

Anaesthetic stimulation of Amaranthus albus seed germination: Interaction with phytochrome

Exposure to solutions of acetaldehyde, ethanol and n‐propanol ranging from 0.06 to 0.6 M for about 5 h induced photosensitivity in imbibed Amaranthus albus L. seeds which normally would be insensitive. When the seeds were made dormant by pre‐treattnent with continuous incandescent light for 24 h, n‐propanol promoted germination np to 80% provided the active form of phytochrome was present. Pre‐treatment of seeds with continuous incandescent light terminated by far‐red reduced the n‐propanol‐stimulated germination to about 33% which could again be increased by a red irradiation. Red light and n‐propanol also interacted in seeds made insensitive to red treatment by 20°C in darkness. Loss of the n‐propanol stimulation resulted from treatment in continuous far‐red for 2 or more days, even when a red irradiance and n‐propanol treatment were combined. It is suggested that n‐propanol may act at a membrane level.

The Effect of Light Duration on Turkey Poult Performance and Adrenal Function

Day-old tom poults were exposed to one of the following light treatments: 1) continuous incandescent light (24LL), 2) 23L:1D incandescent light, 3) 12L:12D incandescent light, or 4) natural day lengths only. Mortality was recorded daily. At Weeks 1, 2, 4, 6, and 8, after poult placement, body weights and feed consumption were measured. At each of these times, 10 poults were sacrificed from each treatment group for evaluation of plasma corticosterone.Day lengths utilized in this study had no consistent effect on poult-performance parameters except from 0 to 2 weeks of age. During this time, poults in the 24LL and 23L:1D treatments consumed less feed but were similar in body weight to poults in the other treatments. Adrenal function was also not consistently affected by day length. However, in all treatment groups plasm a corticosterone was lowest during the first 2 weeks posthatching, when compared to hormone levels at 4, 6, and 8 weeks. The lower corticosterone that occurred during the first 2 weeks posthatching may be involved in early poult mortality.

Photoinduced Buphthalmic Avian Eyes: 1. Continuous Fluorescent Light

Numerous investigations of light induced avian buphthalmia using incandescent light have not defined an etiology. Chickens raised from 2 weeks of age in continuous fluorescent light developed shallow anterior chambers and buphthalmos within the first month of treatment. Chickens raised in continuous fluorescent light developed ocular enlargement similar to that reported in chickens raised in continuous incandescent light. Corneal diameters and axial globe lengths were an inconsistent means of documenting ocular enlargement. Iridocorneal angles were narrowed on scanning electron microscopy.

A Flexible In Vitro Shoot Culture Propagation System for Sugarbeet that Includes Rapid Floral Induction of Ramets1, 2

In vitro shoot cultures of sugarbeet (Beta vulgaris L.) were established from lateral buds of flowering plants, providing a flexible vegetative propagation system for a polycross breeding scheme. Monthly transfers of cultures on Murashige‐Skoog medium with 1.1 µM benzyladenine had a shoot multiplication rate of 3 to 5 per month, with higher rates at more frequent transfers. Shoots were rooted on Murashige‐Skoog medium with 16 µM α‐naphthalene‐acetic acid or in Jiffy‐7 peat pots. Shoots of most genotypes multiplied in vitro by axillary shoot growth as well as by adventitious shoot regeneration from petiole surfaces. Shoot regeneration from petioles increased with greater benzyladenine concentration in the range 0–11 µM, but was less in the presence of 0.38 or 3.8 µM ± cistrans abscisic acid. One genotype failed to regenerate shoots from petioles. Shoot cultures also returned to vigorous growth after 56 weeks storage at 4 C in the dark. Shoot culture ramets from most genotypes tested flowered in as little as 26 days in continuous incandescent light in a growth chamber at 14/10 hours fluorescent light/dark at 20/14 C, without the cold treatment usually employed with sugarbeets.

Effect of Photoperiod on Early Growth and Feed Conversion in the Chukar Partridge

In three separate experiments in 1975 and 1976, growth rate, feed consumption, and mortality were studied in the chukar partridge (Alectoris gracea) kept under constant light, or under cycles of intermittent daily light of different intensities. In experiments 1 (1975) and 2 (1976), 471 and 480 chicks, respectively, were divided into four main groups and given either 12, 16, 20, or 24 hr of continuous incandescent light per day. Beginning at 2 weeks of age, half the chicks in each of the four light treatments were given a reduction of 2 hr light per day every 2 weeks. Those in the remaining half were continued on their original light schedule. In experiment 3 (1976), 400 chicks were divided into eight groups and given either continuous or intermittent light of high (40 lux) or low (4 lux) intensity. The light treatments were continuous, (1L:1D) 12 cycles per 24 hr, (2L:2D) six cycles per 24 hr, and (4L:4D) three cycles per 24 hr.Chicks kept under constant light regimens of continuous or (20L:4D) in experiments 1 and 2 were significantly (P<.05) heavier at 8 weeks of age than comparable birds kept on shorter photoperiods. In experiment 3, birds kept under light regimens of continuous or 12 cycles of (1L:1D) per 24 hr were significantly (P<.05) heavier at 12 weeks of age than comparable birds kept under intermittent light cycles with dark periods longer than 1 hr per cycle. Feed conversion varied among light treatments, but was generally better under continuous or (20L:4D) in experiments 1 and 2, or under continuous or 12 cycles of (1L:1D) per 24 hr in expriment 3. Mortality also varied, among light treatments and averaged about 4% for all tests. It is assumed that strains of chukar partridge selected specifically for rapid growth would respond most favorably to the longer photoperiods, or to the shorter energy-saving photoperiods of (1L:1D) given in 12 cycles per 24 hr.

Phytochrome decay in seedlings under continuous incandescent light

Under continuous high intensity incandescent light the decay of phytochrome in Amaranthus seedlings deviates from the predicted first order rate characteristic of the P fr/P total ratio maintained. This deviation takes the form of a slower decay than would be predicted and is only observed at high intensities. Experiments are presented to test the hypothesis that this reduced rate of decay is the result of a high level of phytochrome intermediates maintained under high intensity incandescent light. Accumulation of intermediates under these conditions has been demonstrated using a quasi-continuous measuring spectrophotometer. They are weakly absorbing and their concentration increases with light intensity. Although they form P fr in darkness, it is proposed that they do not decay. The model predicts that in a sample cuvette, where a light intensity gradient exists, there is more probability of a phytochrome molecule being presnet as P fr at the back of the cuvette: the region of lowest light intensity. Under conditions which favour phytochrome decay, a preferential loss of phytochrome should result at the back of the cuvette and an increasingly higher proportion of the remaining phytochrome will consequently be measured as intermediate as the experiment progresses. The results confirm the hypothesis and in addition, after 60 min incandescent light, demonstrate an accumulation of intermediates which form P fr with a longer half-life that at the begining of the experiment. Pisum epicotyl hooks show no such intermediate accumulation or preferential decay at the back of the cuvette, which is in agreement with the observed first order phytochrome decay under high intensity incandescent light. A scheme is presented explaining the results on the basis of the decay process.

Aspects of phytochrome decay in etiolated seedlings under continuous Illumination

The rate of total phytochrome decay in the dicotyledons Amaranthus caudatus, Mirabilis jalapa and Pisum sativum under continuous illumination with red, incandescent, and blue light depends on the PFR/Ptotal maintained by each source. Amaranthus is an exception to this in that there is a deviation from firstorder decay kinetics under continuous illumination with incancdescent light. This deviation is probably not related to the chlorophyll present in the Amaranthus sample since chlorophyll-rich Pisum buds have the same phytochrome decay rate as epicotyl tissue under continuous incandescent light. Reports of a prolonged lag phase before the onset of first-order decay kinetics of phytochrome in Pisum have not been confirmed and the small lag phase observed in the present work can be accounted for by the time required to attain the PFR/Ptotal ratio characteristic of blue light in a carotenoid rich tissue. In the monocotyledon, Avena sativa, and perhaps monocotyledons in general, decay rate is maximal at a low PFR concentration and the decay curve is the same under continuous red, incandescent and blue light. This dicotyledon/monocotyledon difference with respect to saturation of phytochrome decay does not correlate with the other dicotyledon/monocotyledon difference, the presence or absence of dark reverions of PFR to PR, since the dicotyledons Amaranthus and Mirabilis that lack reversion still show no saturation of decay. Possible growth control by the PFR/Ptotal ratio is discussed in relation to environmental changes in light quality.

Photomorphogenesis in Arabidopsis thaliana (L.) Heynh

Arabidopsis seeds were germinated on sterile mineral agar supplemented with 1% glucose and cultured under continuous light regimes. With 4-hour incandescent plus 20-hour monochromatic illumination in the region from 400 to 485 nanometers there was effective floral induction at an intensity of 100 microwatts per square centimeter. Exclusion of far red wave lengths from the 4-hour incandescent period sharply reduced the effectiveness of subsequent monochromatic blue light in promoting floral induction. Delayed floral induction occurred under continuous incandescent light lacking far red and was attributable to the blue wave lengths. Continuous 485 nanometer (100 microwatts per square centimeter) exposure without any white light treatment during the postgermination growth period was ineffective in floral induction and meristem development. Light at 730 nanometers under the same conditions was partially effective, whereas energy between 500 and 700 nanometers was completely ineffective. When continuous monochromatic light at a 3-fold higher energy level was administered, all photomorphogenic responses were accomplished with 485 nanometer light, including germination and 100% floral induction without any white light treatment at any time during the experiment. Almost equal quantum effectiveness was calculated when equivalent quantum flux densities in the region from 710 to 740 nanometers or at 485 nanometers were used. It is postulated that floral induction in Arabidopsis may be the result of a continuous excitation of a stable form of far red-absorbing phytochrome localized in or on a membrane, and that excitation can be either by direct absorption of energy by far red-absorbing phytochrome or by transfer from an accessory pigment.

Cytokinin-induced Growth Responses by Fenugreek Cotyledons

As shown below, isolated fenugreek (Trigonella foenum graecum L.) cotyledons respond readily to cytokinins with increased expansion. Similar responses have been described for isolated cotyledons of spinach (4) and radish (5) and for sections of Xanthium cotyledons (3). A comparison shows that the fenugreek cotyledons exhibit a higher degree of specificity as they do not respond to GA. The findings may lead to an alternative bioassay of cytokinins. The use of cotyledons has a number of advantages from the point of simplicity in laboratory practice. Also cotyledons exhibiting cytokinin specific responses may be used to investigate the biochemical mechanism of cytokinin action as we report elsewhere (8). Here we describe the expansion of isolated cotyledons as affected by some growth substances, light, nitrogenous compounds, sucrose, and dormancy status. As in other Trifolieae, the attached cotyledons do not merely function as a reserve store, but expand and become green in light. The cotyledons can be separated from the embryonic axis by a cut through the dry seed as the space between these parts is indicated by a groove in the seed exterior. Further manipulationssterilization and washing of cut seeds, their transfer onto wet filter paper in Petri dishes, removal of seed coats 20 hr later, weighing and layering of cotyledons-were done in green safe light. Usually five cotyledons were arranged in a 7-cm Petri dish containing one filter paper disc to which was added 3 ml of test solution containing 1 mg each of mycostatin (nystatin), penicillin, and streptomycin per 50 ml while four to six replicates constituted one treatment. For light treatments the dishes were exposed to continuous incandescent light (30 ft-c near dishes) at 25 C. The dark treatments were enclosed in light tight boxes at the same temperature. CO2 treatment was given by incubating an uncovered Petri dish containing the cut seeds during the initial 20-hr soaking period for 18 hr in a desiccator in which CO2 was released from sodium bicarbonate by hydrochloric acid. To minimize variability due to differences in initial size of cotyledons, results have been expressed as relative increases (%) in fresh weight. Thus, within one experiment equal kinetininduced expansion was observed for samples of seed differing close to 100% in average air dry weight. Figure 1 shows the effect of exposing cotyledons in light to 5 X 10-5 M kinetin for increasing periods of time. In another experiment incubation under identical conditions but in the presence of 20 mM KNO3 resulted in a statistically significant growth stimulation by kinetin after 12 hr. Table I gives the effects of some cytokinins at different concentrations in darkness and in light after 48 hr. Light approximately doubled the growth responses. The lowest concentration at which kinetin gave in light a statistically significant response was 5 X 10-7 M and for 6-benzylade-

The Influence of Incandescent and Infrared Light Upon Chicks

From time to time poultry producers inquire about the cause of a peculiar eye abnormality in young chickens in which the eye appears enlarged and elongated.This condition has been described by Lauber et al. (1961) and was produced by exposing young chicks to continuous incandescent light of 3-foot candle intensity at bird level.Because poultry producers sometimes use various forms of infrared heat lamp equipment, it was desirable to determine if such equipment would cause development of the abnormal eye condition.An experiment was conducted to determine what effect light from two kinds of heat lamps as compared to light from incandescent lamps had upon chicks. Quadruplicate pens of broiler cross chicks11White Vantress male X Cobb White Rock female. equally divided for sex received light as follows:(1) 250 watt infrared heat lamps of red glass—24 hrs.;(2) 250 watt infrared heat lamps of white glass—24 hrs.;(3) 60 watt incandescent lamps—24 hrs.; …

Influence of incandescent and coloured light on chicken embryos during incubation.

Jensen and Matson1 reported increased weight of the eye and flattening of the cornea (probably due to increased ultra-ocular pressure) in chicks exposed to continuous incandescent light. Histological studies of affected eyes, reported by Lauber et al.2, showed thinning of the retinal layers when chicks were subjected to continuous incandescent light. Shutze et al.3 reported that hens reared under continuous incandescent light until 20 weeks of age showed a subsequent effect from continuous incandescent light which was manifest as depressed egg production and blindness. When silkworms were exposed to light at various stages of development, they either spun larger than normal quantities of silk or laid larger numbers of eggs (M. Kato, personal communication, 1961).

Effects of Exposure to Continuous Light on the Eye of the Growing Chick.

SummaryThe influence of continuous incandescent light on the eyes of young chicks has been investigated and a profound enlargement of the eyeball has been observed. The enlargement is associated with an accumulation of fluid in the vitreous body. Histological changes were evident in several layers of the eye with the most striking effect being a thinning of the retina. Exposure to continuous light reduced the thickness of the nerve fiber layer and the layer of rods and cones.