scholarly journals Substrate Acidification by Geranium: Light Effects and Phosphorus Uptake

2008 ◽  
Vol 133 (4) ◽  
pp. 515-520 ◽  
Author(s):  
Matthew D. Taylor ◽  
Paul V. Nelson ◽  
Jonathan M. Frantz
Keyword(s):  
Light Intensity ◽  
Phosphorus Uptake ◽  
Dry Weight ◽  
P Uptake ◽  
High Light Intensity ◽  
High Light ◽  
P Deficiency ◽  
Light Levels ◽  
Direct Light ◽  
Substrate Ph

Sudden pH decline (SPD) describes the situation where crops growing at an appropriate pH rapidly (within 1–2 weeks) cause the substrate pH to shift downward one to two units. ‘Designer Dark Red’ geraniums (Pelargonium ×hortorum Bailey) were grown in three experiments to assess possible effects of light on SPD and phosphorous (P) uptake. The first experiment tested the effect of four light intensities (105, 210, 575, and 1020 ± 25 μmol·m−2·s−1) on substrate acidification. At 63 days, substrate pH declined from 6.0 to 4.8 as light intensity increased. Tissue P of plants grown at the highest two light levels was extremely low (0.10%–0.14% of dry weight). P stress has been reported to cause acidification. Because plants in the two lowest light treatments had adequate P, it was not possible to determine if the drop in substrate pH was a direct light effect or a combination of light and P. The second experiment used a factorial combination of the three highest light levels from Expt. 1 and five preplant P rates (0, 0.065, 0.13, 0.26, or 0.52 g·L−1 substrate) to assess this question. When tissue P concentrations were deficient, pH decreased by 0.6 to 1.0 pH units within 2 weeks and deficiency occurred more often with high light intensity. These data indicated that P deficiency caused substrate acidification and indicated the possibility that P uptake was suppressed by high light intensity. The third experiment was conducted in hydroponics to determine the direct effect of high light intensity on P uptake. In this experiment, cumulative P uptake per gram root and the rate of P uptake per gram root per day both decreased 20% when light intensity increased from 500 to 1100 μmol·m−2·s−1. It is clear from this study that P deficiency causes geraniums to acidify the substrate and that high light suppresses P uptake.

Response of abscisic acid mutants of Arabidopsis to salinity

2002 ◽  
Vol 29 (5) ◽  
pp. 561 ◽  
Author(s):  
Grant R. Cramer
Keyword(s):  
Abscisic Acid ◽  
Light Intensity ◽  
Salinity Stress ◽  
Root Elongation ◽  
High Salinity ◽  
Dry Weight ◽  
Protective Role ◽  
High Light Intensity ◽  
High Light ◽  
Total Dry Weight

Increases in abscisic acid (ABA) concentrations in plant tissues correlate with growth inhibition in salt-stressed plants. Therefore, it was hypothesized that Arabidopsis ABA mutants different in, or insensitive to, ABA would respond differently than wild type (wt) to salinity stress. Seeds (wt, abi1-1, abi2-1, abi3-1, and aba1-3) were germinated and grown hydroponically in three separate experiments with different environmental conditions: relative humidity at 80 or 100%, day/night temperatures at 21/18 or 23/20˚C, and light intensity at 125, 200 or 350 μmol photons m–2 s-1. Plants were exposed to salinity (either 0, 40 and 80 mM NaCl or 1, 5, and 9 dS m–1 with a Na/Ca ratio of 10 depending on the experiment) for one to several weeks before harvesting. The effect of salinity on root elongation rates of young seedlings was measured as well. Two-way ANOVA of root elongation rates of young seedlings and the growth of 3-week old plants in hydroponic solutions indicated that salinity inhibited growth, increased ABA and Na concentrations, and reduced K concentrations in all genotypes tested. However, there were no significant interactions with salinity and genotype for root elongation rates, total dry weight, shoot ABA and K concentrations. Shoot Na concentrations were significantly higher in wt plants relative to other genotypes subjected to high salinity stress. aba1-3 had significantly lower ABA concentrations than other genotypes, but the interaction of aba1-3 with salinity was the same as other genotypes. The lack of difference in interaction between genotype and salinity indicates that all genotypes responded in the same manner and amount to salinity for the particular parameter measured. Therefore, it appears that there are no significant differences in growth in response to salinity between the ABA mutants (ABA-deficient and ABA-insensitive) and wt. However, in contrast to the other genotypes, some of the ABA-deficient plants, aba1-3, died when exposed to high salinity and high light intensity. ABA appears to provide a protective role in conditions of high salinity and high light intensity.

Effect of Climatic Conditions on Phytotoxicity of Terbutryn

Weed Science ◽  
1972 ◽  
Vol 20 (1) ◽  
pp. 60-63 ◽  
Author(s):  
L. F. Figuerola ◽  
W. R. Furtick
Keyword(s):  
Light Intensity ◽  
Dry Weight ◽  
High Light Intensity ◽  
Climatic Conditions ◽  
High Light ◽  
Controlled Environment ◽  
Low Light ◽  
Carbon Dioxide Uptake ◽  
Low Light Intensity ◽  
The Difference

Phytotoxicity of 2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine (terbutryn) on winter wheat (Triticum aestivum Vill. ‘Host’) was investigated in a controlled environment. Highly significant differences in foliage dry weight were caused by different light intensities and rates of terbutryn. Injury symptoms appeared much earlier in plants under high light intensity. Carbon dioxide uptake by wheat plants was reduced by terbutryn at high light intensity. At low light intensity the reduction was less severe and developed later. Respiration (CO2 evolved in the dark) was reduced only by the highest rates. Terbutryn was significantly less toxic to wheat than 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine). The difference was more noticeable at low rates under high light intensity. At low light intensity no injury was observed with terbutryn.

Influence of Application Variables on the Foliar Efficacy of Saflufenacil on Horseweed (Conyza canadensis)

Weed Science ◽  
2015 ◽  
Vol 63 (3) ◽  
pp. 578-586 ◽  
Author(s):  
Tracy G. Mellendorf ◽  
Julie M. Young ◽  
Joseph L. Matthews ◽  
Bryan G. Young
Keyword(s):  
Light Intensity ◽  
Low Temperatures ◽  
Dry Weight ◽  
High Light Intensity ◽  
High Light ◽  
Conyza Canadensis ◽  
Solution Ph ◽  
Low Light ◽  
Spray Solution ◽  
High And Low Temperatures

Greenhouse studies were conducted to determine the influence of spray-solution pH, adjuvant, light intensity, temperature, and glyphosate on the efficacy of saflufenacil on horseweed. Control of glyphosate-resistant horseweed from saflufenacil alone was greatest with a spray-solution pH of 5, compared with pH 7 or 9. However, when glyphosate was added to saflufenacil, similar GR50values were measured with spray solutions adjusted to pH 5 and 9, and horseweed control at pH 9 was 38% greater than at pH 7. The efficacy of saflufenacil on horseweed was 36% greater when crop oil concentrate was used as an adjuvant compared with nonionic surfactant, regardless of the addition of glyphosate or the sensitivity of the horseweed population to glyphosate (resistant vs. susceptible). The addition of glyphosate to low rates of saflufenacil increased control over saflufenacil applied alone on glyphosate-susceptible and -resistant horseweed. Saflufenacil activity was greater under low light intensity (300 μmol m−2s−1) than high light intensity (1,000 μmol m−2s−1). Although initial horseweed control was greater under high temperature (27 C) compared with low temperature (10 C), by 21 d after treatment horseweed dry weight was similar from saflufenacil applied under high and low temperatures.

scholarly journals Effects of light intensity and the remaining nitrate concentration on the beta-carotene accumulation of a wild Dunaliella salina strain isolated from the saline soil

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Zhe Wu ◽  
Rokeya Akter ◽  
Wallop Arirob ◽  
Niran Juntawong ◽  
Chunhong Ma ◽  
...  
Keyword(s):  
Light Intensity ◽  
Dunaliella Salina ◽  
Saline Soil ◽  
Nitrate Concentration ◽  
Beta Carotene ◽  
Dry Weight ◽  
High Light Intensity ◽  
High Light ◽  
Northern Thailand ◽  
Cultivation Time

An isolated <em>Dunaliella salina</em> strain from northern Thailand was cultured in modified Johnson’s medium in column photobioreactor. The beta-carotene accumulation mainly depended on the quantities of cells entering into carotenogenesis condition that was significantly enhanced by high started KNO3 concentration. Low remaining nitrate concentration in the culture of each cell (RNCC) was suitable for algae to accumulate beta-carotene. Following the cultivation time extended, RNCC of all cultures decreased and tended to the same level (10-20 pg/cell) although the biomass or betacarotene content in the culture was higher in high started KNO3 concentration. High light intensity restrained the growth especially in low KNO3 concentration but improved betacarotene accumulation and RNCC. The highest biomass and beta-carotene dry weight (DW) were 2.25 g L-1 and 79.2 mg g-1 DW respectively. Above results indicated that increasing the biomass and as early as possible to strengthen the stress on each cell was important to improve the final beta-carotene yield.

Photo-dependent population dynamics of Stentor coeruleus and its consumption of Colpidium striatum

2007 ◽  
Vol 85 (5) ◽  
pp. 674-677 ◽  
Author(s):  
M.W. Cadotte ◽  
S. Jantz ◽  
D.V. Mai
Keyword(s):  
Light Intensity ◽  
High Light Intensity ◽  
Light Treatment ◽  
High Light ◽  
Ambient Light ◽  
Population Responses ◽  
Physiological Processes ◽  
Light Levels ◽  
Stentor Coeruleus ◽  
Predator System

The predatory protozoan Stentor coeruleus Ehrenberg, 1830 is known to show photosensitivity and photodispersion, avoiding regions of high light intensity as an antipredation strategy. This physiological and behavioral response to light likely has demographic consequences. We manipulated light intensity to determine population responses of S. coeruleus and the resulting effects on its prey Colpidium striatum Stokes, 1886. We show that S. coeruleus maintained the highest population density under ambient light levels and low densities under both high and no light treatments. The results from the no light treatment were surprising because little work has been done on possible important behavioral and physiological processes cued by light. These results add power to the use of S. coeruleus as a model predator system to test ecological dynamics and processes associated with predation.

Time Estimation in Humans: Effects of Ambient Illumination and Sex

1981 ◽  
Vol 53 (3) ◽  
pp. 747-750 ◽  
Author(s):  
Eugene R. Delay ◽  
Maryjo A. Richardson
Keyword(s):  
College Students ◽  
Light Intensity ◽  
Analysis Of Variance ◽  
Time Estimation ◽  
High Light Intensity ◽  
High Light ◽  
Female College Students ◽  
Ambient Illumination ◽  
Light Levels ◽  
Arousal Theory

7 male and 7 female college students made estimations of 15-sec. intervals in conditions of dark, low and high ambient illumination. Analysis of variance showed significant effects of illumination and illumination by sex. Increased light levels shortened time estimation except for males under high light intensity. Results are discussed in terms of arousal theory and the relevance of these factors in research on time estimation.

Differential Response of Palmer Amaranth (Amaranthus palmeri) Gender to Abiotic Stress

Weed Science ◽  
2017 ◽  
Vol 65 (2) ◽  
pp. 213-227 ◽  
Author(s):  
Nicholas E. Korres ◽  
Jason K. Norsworthy ◽  
Toby FitzSimons ◽  
Trent L. Roberts ◽  
Derrick M. Oosterhuis
Keyword(s):  
Light Intensity ◽  
Weed Management ◽  
Light Stress ◽  
Nutrient Deficiency ◽  
Dry Weight ◽  
Experimental Period ◽  
High Light Intensity ◽  
High Light ◽  
Palmer Amaranth ◽  
Total Dry Weight

Knowledge of Palmer amaranth biology and physiology is essential for the development of effective weed management systems. The aim of this study was to investigate the response of Palmer amaranth gender to nutrient deficiency and light stress. Differential gender responses were observed for all the growth, phenology, and photochemistry parameters measured. Female plants, for example, invested more in height, stem, and total dry weight, whereas male plants invested more in leaf area and leaf dry weight. The growth rate of females was higher than that of male Palmer amaranth plants, although both followed similar declining trends as the experimental period progressed. Initiation of flowering of female plants occurred 6 to 8 d earlier compared with male plants. Nitrogen and to a certain extent phosphorous were the most influential nutrients that affected measured parameters in both Palmer amaranth genders, particularly under high light intensity. Electron transport rate and chlorophyll content of female Palmer amaranth plants compared with male plants was lower at high light intensity in combination with nitrogen and phosphorous deficiencies. There is a potential to manipulate Palmer amaranth population structure by altering microenvironments at the field level.

Growth kinetics of Marquis wheat. I. Light dependence

1972 ◽  
Vol 50 (1) ◽  
pp. 89-99 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Light Intensity ◽  
Growth Kinetics ◽  
Complex Form ◽  
Dry Weight ◽  
High Light Intensity ◽  
High Light ◽  
Rate Coefficients ◽  
Primary Analysis ◽  
Growth Coefficient ◽  
Root Dry Weight

As early growth is exponential it was measured as the pseudo-first-order rate coefficient, k1′. The growth coefficient is independent of the method of measurement, so different values derived from different measurements such as dry weight, fresh weight, chlorophyll content, and area reflected somewhat different aspects of growth in a given organ. At low light intensity k1′ was highest for lamina dry weight and lowest for root dry weight, and at high light intensity, highest and lowest k1′.were obtained for "stem" dry weight and lamina area, respectively. The differences in rate coefficients between organs were less than 10% of their values at high light intensity. The rectangular hyperbolic fit of the dependence of k1′ on light intensity was used to compute a maximum value (kmL) independent of light intensity. A kmL of 0.34 per day was obtained for plants of Marquis wheat grown at 25 °C with Hoagland's solution in Went's medium under controlled environment, and the highest value, 0.37, was achieved by dry weight of "stems." A complex form parameter was also computed, and it included a function of the efficiency of light use for growth, which was highest for leaf area and lowest for root dry weight. Measurements on complete morphological entities such as whole organs are best interpreted. Growth kinetics and its relationship to "growth analysis" were discussed in distinct favor of the former approach. The growth coefficient as the relative growth rate has been abused and that term should be dropped. The prospects of kinetic or primary analysis as the standard quantitative method are great, as initially envisaged by V. H. Blackman half a century ago.

Characteristics of Photosynthesis in Different Wheat Cultivars under High Light Intensity and High Temperature Stresses

2009 ◽  
Vol 34 (12) ◽  
pp. 2196-2201 ◽  
Author(s):  
Xue-Li QI ◽  
Lin HU ◽  
Hai-Bin DONG ◽  
Lei ZHANG ◽  
Gen-Song WANG ◽  
...  
Keyword(s):  
High Temperature ◽  
Light Intensity ◽  
High Light Intensity ◽  
High Light ◽  
Wheat Cultivars ◽  
Temperature Stresses
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