High Light Intensity Conditions Research Articles

Effect of anterior ganglia removal on phototaxis in the earthworm mbriscus terrestris)

One hundred and sixty earthworms were tested in an escape task. Half had their anterior ganglia removed 24 h prior to testing and half were intact. Half of each group was tested using a 100-W light source as the aversive stimulus, the remainder using a 150-W light source. Each subject was allowed a maximum of 5 min to escape following light onset. All subjects responded faster in the high light intensity condition. Subjects with their anterior ganglia removed escaped faster than controls under the 100-W light intensity condition, indicating the possibility that a specialized temporary lens-like and sensory cell activation follows anterior ganglia removal.

The relationship between carbonic anhydrase activity and glycolate excretion in the blue-green alga Coccochloris peniocystis

The rate of glycolate excretion by Coccochloris peniocystis Kütz. cells incubated under conditions of low bicarbonate concentration and high light intensity was linear for only the initial 15 min of incubation and no additional glycolate accumulated in the medium after 20 min. Excretion was maximal in cells grown on 5% CO2 in air when transferred to an incubation medium containing no added bicarbonate. The inhibitor INH (isonicotinyl hydrazide) had no measurable effect on the amount of glycolate released whereas HPMS (α-hydroxy-2-pyridyl methanesulfonate) stimulated excretion 3-fold. Cells transferred to air from growth on 5% CO2 in air increased in carbonic anhydrase activity, while a decrease occurred in the cells' ability to excrete glycolate. Cells grown on air and switched to 5% CO2 in air showed an increase in their ability to excrete glycolate with a concomitant decrease in carbonic anhydrase activity. Diamox, a specific inhibitor of carbonic anhydrase, was found to stimulate excretion with both airgrown and 5% CO2-grown cells which had been off 5% CO2 for approximately 30 min. The rate of carbon fixation by 5% CO2-grown cells put on air was found to rise over a 110 min period, corresponding to both the induction period of carbonic anhydrase and the period of decline in the ability of the cells to excrete glycolic acid. These results suggest that the absence of carbonic anhydrase in 5% CO2-grown cells causes a stimulation of glycolate excretion when these cells are transferred to a low bicarbonate medium, because of an increased rate of glycolate formation due to the oxidation of ribulose diphosphate by molecular oxygen at low internal CO2 concentrations.

Flower formation in Calceolaria × herbeohybrida Voss

At high light intensity Calceolaria × herbeohybrida ‘Zwerg Meisterstück’ is a long-day plant with a critical day-length of 14–15 h. At low light intensity (e.g. as in winter) flowering will take place if the long-day treatment is preceded by a chilling period (10°C) or by short days at 15–20°C. During the chilling period day-length is of little influence. With increasing duration of the chilling period the requirement for long days decreases and the critical day-length becomes shorter. After a sufficient chilling period, flowering occurs both in long and short days. If the chilling period lasts approx. 40 days, however, flowering in short days is delayed, phyllody occurs and only a small number of flowers develop in comparison to long days. After at least 70–75 days of chilling plants show almost the same reaction in short and long days. Plants not chilled under conditions of high light intensity and short days flower either in naturally long days or by day extension with incandescent light. After chilling, fluorescent light of the type L 39 is also effective for day extension. A night break with incandescent light in a 16-h dark period induces flowering only after a chilling period. Incandescent but not fluorescent light causes a slight yellowing and more upright position of the leaves and an elongation of the internodes.

Effects of light intensity, oxygen concentration, and carbon dioxide concentration on photosynthesis in algae

The effects of various combinations of light intensity, oxygen concentration, and CO2 concentration on photosynthesis and growth in several algal types were studied. The results suggest the following. (1) Different algae show different responses to high oxygen concentrations and high light intensities. (2) Inhibition of photosynthesis (CO2 fixation and growth), if seen, increases with increasing oxygen concentration and with increasing light intensity (at light intensities greater than saturation). (3) The inhibition of net photosynthesis observed cannot be attributed to high light intensity alone. (4) The inhibition cannot be attributed to increased rates of excretion of organic materials under conditions of high oxygen concentration and high light intensity. (5) Increased concentrations of CO2 can decrease the effect of high oxygen and light in some algae. (6) The decrease in net photosynthesis observed is probably the result of photorespiration. (7) The effect of light intensity, oxygen concentration, or CO2 concentration on algal photosynthesis should not be studied without considering the effect of the other factors. Some implications of these results, as related to primary productivity measurements, are also discussed.

Comparative Productivity of Four Carolina Lakes

Field data for 14C uptake in two reservoirs, a Carolina bay and an oxbow in South Carolina indicate that lakes of this region are low in primary productivity compared to lakes elsewhere for which published values are available. Par Pond, a reactor-cooling reservoir, is the only lake studied which shows even moderate productivity. Factors which may be related to productivity in these lakes include nutrient level, water temperature, light penetration as influenced by turbidity and water color, and stratification as influenced by local topography and lake morphometry. Limnological characteristics of the four South Carolina lakes are summarized. INTRODUCTION Relatively few limnological studies have been conducted on the lakes of South Carolina. This report presents the results of preliminary carbon fixation measurements during 1967 in four lakes in the vicinity of the Savannah River Laboratory. The four lakes include two reservoirs, a Carolina bay and a Savannah River oxbow. The reservoirs are Clark Hill, a 28,000-acre impoundment of the Savannah River, and Par Pond, a 2500-acre lake which receives reactor-cooling effluent on the Savannah River Plant site. The Carolina bay is Clear Pond, a 27-acre lake between Bamberg and Ehrhardt, S. C., off Route 601. The Savannah River oxbow is Big Snooks Lake, an 11-acre oxbow located along the Savannah River near Tillman, S. C. The lakes are in the coastal plain except Clark Hill which is in the Piedmont plateau. All lie in the Savannah River drainage except for Clear Pond which is in the Salkehatchie River drainage. Some of the basic limnological features of these lakes or their sampling stations are given in Tables 1 and 2. Marshall and LeRoy (1971) have described limnological features of Par Pond in greater detail, and Marshall and Tilly (1971) have presented information on the annual cycle of primary productivity. METHODS Samples were taken from the deepest area in each lake. In the reservoirs, this was near the dams. In an attempt to make comparisons meaningful, productivity determinations were made for 3 hr at about the same times of day, usually from 1030 to 1330 hr and never later than 1400 hr. Highly variable weather obviated plans to conduct experiments on only clear days; however, the darkest days were avoided, and all measurements were made under conditions of high average light intensity. Water was secured at 1-m depth intervals 1 This paper was prepared in connection with work under Contract No. AT(07-2)-1 with the U. S. Atomic Energy Commission.

Effects of kaolinite as a reflective antitranspirant on leaf temperature, transpiration, photosynthesis, and water‐use efficiency

Transpiration and photosynthesis are influenced by the optical properties of leaves. Application of a uniform white coating of kaolinite (about 225 mg dm−2) to the upper leaf surface produced significant changes in the spectral curves (reflectivity, transmissivity, and absorptivity) of Valencia orange leaves. Photosynthetic light response curves of leaves of orange, lemon, rubber plant (all hypostomatous), and bean (amphibiostomatous) were modified by the reflective material, which at low light intensities decreased photosynthetic rates and increased light saturation levels. The white coating cooled the leaves 3–4°C and reduced transpiration 22–28% under conditions of high light intensity, warm air, low relative humidity, and low wind velocity. However the rubber plant under the same conditions showed a smaller reduction in transpiration (less than 10%), indicating effective self‐regulation of its water loss. These experiments demonstrated that water‐use efficiency of leaves can be improved, particularly under high light intensities.

Effect of Leaf Aging on Water Deficit—Water Potential Relationships of Dogwood Leaves Growing in Two Environments

AbstractWater deficit‐water potential relationships were determined at approximately monthly intervals from May to August on leaves collected from dogwood trees growing in two environments. The relationships were not the same for leaves of different ages or for leaves of the same age, but growing in the different environments. With aging of the leaves, the relationships shifted to progressively lower water potentials for a given water deficit. Increased leaf dry weight, decreased cell wall elasticity, and decreased osmotic potentials accompanied leaf aging. These changes and the shifts in the relationships were greatest for leaves growing under high light intensity and dry environmental conditions. The lack of constancy in the relationships reduces the usefulness of water deficit or relative turgidity as an estimator of water potential. For the purposes of some workers, however, the relationships may be sufficiently constant for mature leaves of a given species growing in a relatively constant environment.

Granite Outcrop Communities of the Piedmont Plateau in Georgia

Communities in depressions, occurring as islands surrounded by naturally exposed granitic rock, were classified by the correlated of maximum soil depth and characteristic vegetation cover into: diamorpha communities, 2—6 cm; lichen—annual herb communities 16—39 cm; and herb—shrub communities, 40—50 cm. The total flora of the 40 island communities, included 76 species, but only 39 of these occurred in five or more communities and were considered characteristic. The extreme environmental conditions of high light intensity and low soil moisture content were indicated by the fact that of the 20 plants present in over 50% of the communities, 18 were lichens, mosses, and flowering annuals and only two were perennial flowering plants. The flora of the island communities is distinct from that of border vegetation. Only three endemics are among the 39 characteristics plants. Seasonal aspects of the outcrop vegetation are striking. During the winter months, November through February, mosses and lichens are most con...

The Influence of Several Transpiration Suppressants on Transpiration, Photosynthesis, and Water-Use Efficiency of Cotton Leaves

The influence of transpiration suppressants on transpiration and apparent photosynthesis of cotton leaves was investigated under moderate and high light intensity (7'5 and 22�5x 104 erg cm-2 sec-I) and low windspeed (1-5 and 3�1 em sec-I) conditions. The substances used were Adol 52 (n formulation of cetyl alcohol), OED Green (a formulation of oxyethylene docosanol), 8�600 (n plastic transplanting spray), and phenyl mercuric acetate.

Bagging Possibly Reduces Success in Oat Crossing

Agronomy JournalVolume 48, Issue 4 p. 191-191 Note Bagging Possibly Reduces Success in Oat Crossing Franklin A. Coffman, Franklin A. Coffman Senior Agronomist Oat Investigations, Field Crops Research Branch, A.R.S., U.S.D.A., Beltsville, Md. (Credit is due H. C. MURPHY, Principal Pathologist in Charge of Oat Investigations, for suggesting this study be made by the writer, and suggesting that possibly under conditions of high light intensities, bagging increases the temperature.)Search for more papers by this author Franklin A. Coffman, Franklin A. Coffman Senior Agronomist Oat Investigations, Field Crops Research Branch, A.R.S., U.S.D.A., Beltsville, Md. (Credit is due H. C. MURPHY, Principal Pathologist in Charge of Oat Investigations, for suggesting this study be made by the writer, and suggesting that possibly under conditions of high light intensities, bagging increases the temperature.)Search for more papers by this author First published: 01 April 1956 https://doi.org/10.2134/agronj1956.00021962004800040013xCitations: 2 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume48, Issue4April 1956Pages 191-191 RelatedInformation

Further Studies on Vegetative and Fruiting Responses of Tomatoes to High Temperature and Light Intensity

1. This paper reports the continuation of the studies begun in 1951 on the influence of high temperature and high light intensity on the vegetative and fruiting responses of tomatoes. 2. Marglobe and Rutgers plants transplanted prior to the period of high temperature-high light intensity fruited normally only before the occurrence of unfavorable temperature and light conditions, while those transplanted directly into the conditions of high temperature-high light intensity grew slowly but did not fruit. 3. Marglobe and Rutgers plants in the field did not respond to sprays of parachlorophenoxyacetic acid (CPA) during the unfavorable light-temperature period, whereas summer-setting varieties and selections cluster-sprayed with CPA nearly doubled their fruit production. 4. Shaded Marglobe and summer-setting varieties had a significantly greater stem height than unshaded plants. Shading or defoliation alleviated light inhibition of the growth rate. 5. Dormancy of fruits of the S-616 variety can be attributed p...

The effect of thioctic acid on the quantum efficiency of the hill reaction

1. 1. Conditions have been defined under which 6-thioctic acid (6T) increases the quantum efficiency of the Hill reaction in Scenedesmus. This increase occurs when the control rate is quinone-limited, under conditions of high light intensity, low quinone concentration, high temperature, and high algal density. When the control rate is inhibited by high concentrations of quinone or photolyzed quinone, 6T results in a further decrease in rate. 2. 2. Fundamental characteristics of the Hill reaction suggest that 6T either increases the rate at which water is separated into reduced and oxidized fragments (quantum conversion agent) or decreases the rate at which these fragments later recombine (hydrogen carrier or quinone diffusion). 3. 3. The variation of the effect with 6T concentration, incubation conditions, pH, quinone concentration, temperature, preillumination of quinone, dark contact time with quinone, light intensity, algal density, sulfhydryl poisons, plant species, and other reagents does not permit an unequivocal discrimination between the two possible mechanisms.

Effect on berry production of varied day length during the life of two triumph potato strains

With an intermediate strain of Triumph potatoes (Triumph 22), the continual use of long photoperiods until pollination time resulted in the most berries. When long photoperiods were used during relatively short intervals in the life of the plants, they appeared to be most useful when the flowers were making their final development. Long photoperiods very early in the life of the plant were very useful for berry production, but were not indispensable and unless the long photoperiods were continued for 60 or 70 days they brought about the production of relatively few’ berries. Berry production occurred with an 18-hour photoperiod, but production was only one-third as great as with a 24-hour photoperiod. No berries were developed by the very early strain (Triumph 12) with an 18-hour photoperiod and with this strain berries were produced with only four of the 24-hour photoperiod treatments. Our evidence indicates that induction of flowering in Triumph potatoes by using long photoperiods for short intervals of time is not feasible and except under very favorable conditions of high light intensity it is not possible.

Effects of some Environmental Factors on Photoperiodic Induction of Beet and Dill

1. If maintained on continuous light in the greenhouse, dill flowered in 40 days after sowing the seeds and beet in 31 days. Under conditions of relatively constant illumination at 1000-1400 foot-candles, dill required 40 days from time of planting to show some stem elongation; approximately 20 more days were required to bring about the same response under 500 foot-candles. Under similar conditions of constant illumination of high intensity, beet produced seed stalks 28 days after planting. On the other hand, beet grown under 500 foot-candles did not produce seed stalks. 2. With increasing amounts of illumination during the middle of the dark period, up to 6 hours, the average height of the dill plants was almost directly proportional to the amount of supplementary illumination received. 3. Under conditions of high light intensity, dill may be induced to flower by giving it one long photoperiod consisting of 20-21 hours of light and 4-3 hours of dark. Rapidity of stem elongation was about the same when the plants received one, two, or three long photoperiods. But if the plants received four long photo-periods, they elongated about as rapidly as those maintained on long day. 4. Dill plants previously treated with a high light intensity showed a response to continuous illumination of only 5 foot-candles if exposed to it for as little as 1 day. Those subjected to this treatment for 2 days showed some response, while those having 3-8 days of low light continuously were very slow in responding. 5. When dill was pre-treated with three short photoperiods each consisting of 9 hours of light of 4-12 foot-candles and 15 hours of darkness, and then subjected to intensities of 50-1000 foot-candles, there was a steady increase in average height with increase in intensity up to 300 foot-candles. The effect of higher intensities (500-1000 foot-candles) on rate of stem elongation was approximately the same as that produced by 200 foot-candles. 6. The effect of low temperature (4.5⚬ C.) on dill plants receiving cycles consisting of 20 hours of light and 4 hours of darkness was to suppress markedly the flowering response. Those plants receiving 2 days of cold treatment attained a greater height than did any of those receiving fewer or more days of such treatment. 7. A large proportion of young dill plants elongated their stems if the roots or stems were injured. Thus injury seemingly altered the metabolism sufficiently to bring about the flowering response. 8. Red light of wave lengths greater than 580 μ are capable of inducing the flowering response in dill when used as the sole source of illumination during the induction period. 9. Although red light of 50 foot-candles was approximately as effective in bringing about induction in dill as any intensity up to 500 foot-candles, it was not nearly so effective after 5 days of treatment as the higher intensities. 10. Annual beet did not flower if it received more than 10-11 hours of darkness in each 24. 11. Annual beet began to bolt after return to short day if it received 11 days of continuous light. The bolting of such plants, however, was no more rapid or pronounced than in those receiving cycles consisting of 21 hours of light and 3 hours of darkness. 12. Continuous illumination with 900-1000 foot-candles of light from white fluorescent Mazda lamps, under conditions of only slight temperature fluctuation, was conducive to flowering in beet. If the intensity did not rise above 700 foot-candles during the induction period, flowering did not occur. 13. Annual beet did not flower if subjected to the following cycles of light and dark: (a) 5 minutes of light and 5 minutes of dark (55 days); (b) 30 minutes of light and 30 minutes of dark (55 days); (c) 24 hours of light and 24 hours of dark (117 days); (d) one short photoperiod of 8 hours of light, 16 hours dark and one long photoperiod of 21 hours of light, 3 hours dark (117 days); (e) three short photoperiods of 8 hours of light, 16 hours dark and three long photoperiods of 21 hours of light, 3 hours dark (117 days).14. Exposure of a single leaf of beet to cycles of 20 hours of light and 4 hours of darkness did not result in the plant flowering.