Higher Levels Of Chlorophyll Research Articles

Population structure and energetics of the shallow-water antarctic sea star Odontaster validus in contrasting habitats

Individuals and populations of Odontaster validus Koehler differed markedly among different habitats, as revealed in a study from October 1984 through January 1986 in McMurdo Sound, Antarctica. At McMurdo Station, individual sizes (wet weight) and population biomass (g wet wt m-2 and kJ m-2) decreased significantly with increasing depth. Individuals from shallow (10 to 20 m) habitats were in superior nutritional condition to those from deeper water (30 and 165 m), as shown by higher gonad and pyloric cecum indexes, and by higher lipid and energetic levels in the pyloric ceca. Moreover, gonadal output (reproductive output) was higher in shallow-water individuals. Higher levels of chlorophyll in the pyloric ceca and richer yellow to red coloration of the body wall in the shallow-water individuals indicate that they utilize the higher levels of primary production at shallow depths. At East Cape Armitage, where nearly permanent, thick, snow-covered ice most of the year resulted in very low levels of benthic primary production, the lowdensity sea stars were all very small and nutritionally similar to the deep-water individuals at McMurdo Station. At Cape Evans, where the generally snow-free sea-ice that broke up in mid-summer resulted in a luxurient benthic cover of diatoms and macroalgae, the sea stars were smaller than at McMurdo Station at comparable depths, but population densities were higher, resulting in 4 to 9 times greater biomass. Growth rates of sea stars fed in the laboratory were very low, especially compared to laboratory-reared temperate and tropical species; well-fed individuals need about 9 yr to reach 30 g wet weight, near the mean size of shallowwater individuals at McMurdo Station. No growth was detected in individuals caged at McMurdo Station for one year, suggesting even lower growth rates in the field. The stable size-frequency distributions at the different sites and depths throughout the year-long study suggest highly stable populations with low temporal variability in recruitment, migration and mortality. These data indicate that individuals and populations of O. validus quantitatively and qualitatively reflect the general level of productivity of a habitat. Differences noted in size, coloration, nutrition, and reproductive effort may be the result of long-term integration of local levels of primary production. These ubiquitous sea stars may serve as a biotic indicator of productivity in localized habitats around the continental shelf of Antarctica.

Contribution of Metabolites of Photosynthesis to Postillumination CO2 Assimilation in Response to Lightflects

In the shade plant Alocasia macrorrhiza grown in low light, photosynthetic CO(2) assimilation during a 5 second lightfleck plus postillumination CO(2) assimilation can allow up to 60% more photosynthesis than that which occurs during 5 seconds of steady state light of the same intensity (RL Chazdon, RW Pearcy 1986 Oecologia. 69: 524-531). Metabolites of photosynthesis were measured to determine if the pool of ribulose 1,5-bisphosphate (RuBP) could account for all of the postillumination CO(2) assimilation following a lightfleck in Alocasia. It was found that the pool of triose-P was much larger than that of RuBP and could account for five times more postillumination CO(2) assimilation than could RuBP. The same trend was seen in the sun plant Phaseolus vulgaris when it was grown in the shade. In contrast, sun-grown Alocasia and Phasiolus did not have a large pool of triose-P relative to RuBP following a lightfleck. In sun plants, carbon may rapidly be converted to RuBP in the light whereas in shade plants there may be a restriction in the path between the triose-P and RuBP pools. It is hypothesized that in shade plants the buildup of triose-P rather than RuBP during the lightfleck prevents inhibition of electron transport which may otherwise occur because of competition for ATP between the two kinases of the photosynthetic carbon reduction cycle. Utilization of the triose-P for postillumination CO(2) fixation would require the capacity for significant postillumination ATP synthesis. The extensive grana stacking and large intrathylakoid space which accompanies the high level of chlorophyll in low-light-grown Alocasia could be an important contributing factor to postillumination ATP formation.

The vertical distribution of zooplankton in the western Irish Sea

Zooplankton diel vertical migration is evident on the mixed isothermal side of the western Irish Sea frontal system but is often influenced by large tides and persistent geostrophic currents. On the stratified side of the front, temperature acts as a controlling factor with most of the zooplankton occurring above the thermocline and carrying out pronounced vertical migration when chlorophyll a levels are low and diffuse. At higher chlorophyll levels, when discrete chlorophyll a maxima form, zooplankton vertical movement may be greatly modified with a large number of species and stages concentrating within these maxima at all times of the diel light cycle.

The effect of foliar application of fulvic acid on water use, nutrient uptake and yield in wheat

The effect of foliar application of fulvic acid (FA) on water use, nutrient uptake and yield in wheat was studied in pot experiments and in field trials. FA reduced the stomatal conductance of well-watered plants in pots from ~0.80 to ~0.25 cm s-1. The stomatal conductance of control plants fell continuously from ~0.85 m s-1 to almost zero over a 9-day drying cycle. Plants sprayed with FA at the beginning of the cycle maintained a stomatal conductance of ~0.30 cm s-1 for the whole period. Spraying with FA resulted in a higher level of chlorophyll in the leaves and a greater uptake of 32P by the roots. When droughted at ear-development stage, grain yield was depressed by 30%. Spraying with FA increased the yield of droughted plants to 97% of the irrigated controls. Field trials in North China demonstrated that when FA was used to decrease the water stress or the stress imposed by hot, dry winds during ear development, grain yield increased by 7.3-18.0%.

Phytoplankton dynamics in the central Great Barrier Reef—I. Seasonal changes in biomass and community structure and their relation to intrusive activity

Phytoplankton dynamics in the central Great Barrier Reef and the relation of these dynamics to the seasonal upwelling of nutrient-enriched Coral Sea water onto the outer continental shelf were followed over an annual cycle. Event scale changes were sampled by frequent (2-day to 2-week) re-occupations of a cross-shelf transect during the latter half of the summer. Intrusive activity between November and April episodically injects nitrate-N enriched water into oligotrophic shelf waters. Persistent mid-shelf and intermittent outer shelf mid-water phytoplankton accumulations were observed from late-January to March. The 10, 10to2and<2μm phytoplankton size fractions were, respectively, dominated by diatoms, microflagellates + unarmored dinoflagellates and unicellular cyanobacteria + coccoid eukaryotes + very small flagellates. In the absence of intrusive activity, nanoplankton (10 to 2 μm) and picoplankton (<2μm) dominated biomass. These two size fractions dominated biomass on the outer shelf and in the Coral Sea throughout the year. Picoplankton frequently made up50% of the chlorophyll standing crop. Mid-shelf blooms, in which the highest chlorophyll levels (2μg 1 −1) were found, were largely due to increases of the 10μm fraction. In contrast to marked summer fluctuations of mid-shelf diatom populations, nano- and picoplankton standing crop varied little with time, cross-shelf location or depth. Low water column DIN levels and DIN:Chla ratios suggest phytoplankton populations were nitrogen-limited. In open waters of the central GBR, phytoplankton apparently convert most of the intruded nitrogen into particulate form.

Opposing effects of daminozide and ethylene on the induction of flesh softening in apple fruits

SummaryApple trees were sprayed in late July with daminozide in four seasons to suppress ethylene production and softening of harvested fruit stored in 2% O2, <1% CO2 at 3.5°C. In two out of three years daminozide applied at 0.43 g l−1 was ineffective whereas ethylene production, softening and the rise of soluble pectin were inhibited by 0.85 or 1.7 g l−1. In the third season all the spray treatments were ineffective. In bulk storage experiments a combination of daminozide treatment and ethylene removal by potassium permanganate-impregnated vermiculite led to the retention of fruit firmness in two years out of three; untreated fruit and fruit which received only one of the treatments softened to a similar extent. The dual treatment also inhibited the solubilization of pectin and the synthesis of butyl and hexyl acetates during ripening after storage. Whereas daminozide-treated fruit had higher chlorophyll levels than untreated fruit, ethylene removal had no effect on chlorophyll loss. A taste panel distinguished the low ethylene-daminozide treated fruit as firmer and less mealy than other treatments. However, this fruit had a higher incidence of storage disorders.

Inorganic Nitrogen Control of Growth, Chlorophyll, and Protein Level in Cyanobacterium Nostoc muscorum

Summary The level of photosynthetic oxygen evolution, chlorophyll, protein, phycocyanin, nitrate reductase (NR), and glutamine synthetase (GS) was studied in cyanobacterium Nostoc muscorum growing in combined nitrogen free-, NO − 3 or NH + 4 -medium in order to understand the causes of nitrogen-source-dependent variation in growth. When monitored on the basis of pigment content of culture the growth of Nostoc muscorum was optimal in the presence of NO − 3 rather than in the presence of NH + 4 or molecular N 2 . However, on monitering the growth on the basis of cell number, it was evident that both NO − 3 or N 2 -grown-cultures grew at a almost identical rate, while in NH + 4 -grown-culture growth was sluggish. The inhibition of photosynthetic O 2 evolution by NH + 4 appears to limit growth in the latter case. Although both N 2 and NO − 3 -grown-culture grew at the same rate on the basis of cell number, the NO − 3 -grownculture had a higher level of chlorophyll and protein per cell. It is suggested that this accumulation of pigment and reserve protein in NO − 3 -grown-culture is due to optimization of photoreduction process of NO − 3 by NR coupled with an efficient assimilation of NH + 4 by GS. In view of nitrogen-source-dependent variations in pigment and protein level in Nostoc muscorum cells, it is suggested that the cell number is a better parameter to express growth and enzymatic activities in cyanobacteria rather than the pigment level.

Shade During Growth—Effects on Chemical Composition and Leaf Color of Air‐Cured Burley Tobacco1

AbstractDevelopment of off‐color in air‐cured burley tobacco (Nicotiana tabacumL.) leaf may adversely affect the quality and value of the crop. Shading from other vegetation during growth may be a contributing factor. The purpose of this investigation was to determine the effects of shading during field growth on leaf color and chemical composition of air‐cured burley tobacco. Whole leaves and lamina from air‐cured burley tobacco (cv. Kentucky 14) grown under 0,45, or 65% shade (reduced light) conditions in field (Maury silt loam soil; clayey, mixed, mesic, Typic Paleudalf) experiments were quantitatively analyzed for parameters of color (determined by reflectance), chlorophyll isomers, carotenoids, brown pigment, total phenols, total alkaloids, and nitrate‐N. Whole leaves and lamina from tobacco grown under increased shade generally had more red hue, less yellow hue, less brightness, and more total color change. Lamina from tobacco grown under increased shade had higher levels of chlorophyll a, chlorophyll b, lutein, β‐carotene, neoxanthin, violaxanthin, and nitrate‐N, but lower contents of brown pigment and total alkaloids. Whole leaf grown under increased shade had generally higher contents of nitrate‐N and lower brown pigment, total phenols, and total alkaloids. The color changes in air‐cured whole leaf and lamina associated with increased shade during growth support the hypothesis that shade is one causative factor for the undesirable “pink leaf” characteristic that sometimes develops in air‐cured burley tobacco, although the data do not show that it is the only factor involved.

Nuclear, Virescent Mutants of Zea mays L. with High Levels of Chlorophyll (a/b) Light-Harvesting Complex during Thylakoid Assembly

We have found nuclear, recessive mutants in Zea mays L. where assembly of the major chlorophyll (a/b) light-harvesting complex (LHC) was not delayed relative to most other thylakoid protein complexes during thylakoid biogenesis. This contrasts with the normal development of maize chloroplasts (NR Baker, R Leech 1977 Plant Physiol 60: 640-644). All four mutants examined were allelic and virescent, and displayed visibly higher yields of leaf Chl fluorescence during greening. Fully greened mutants had normal leaf Chl fluorescence yield and normal levels of LHC, and grew to maturity under field conditions. Therefore, delayed LHC assembly is not an obligate feature of thylakoid differentiation.Assigning the molecular basis for the mutation should provide information concerning reguation of LHC assembly. Several possibilities are discussed. The pleiotropic mutant phenotype is not attributable to defects in thylakoid glycerolipid synthesis. Thylakoids isolated from greening mutant leaf sections had elevated glycerolipid/Chl ratios. In addition, both the molar distribution and acyl composition of four major glycerolipids were normal for developing mutant thylakoids.

Phytoplankton Bloom Produced by a Receding Ice Edge in the Ross Sea: Spatial Coherence with the Density Field

Measurements of chlorophyll, particulate carbon, and biogenic silica concentrations near a receding ice edge off the coast of Victoria Land, Antarctica, indicated the presence of a dense phytoplankton bloom. The bloom extended 250 kilometers from the ice edge and was restricted to waters where the melting of ice had resulted in reduced salinity. The region involved was one of enhanced vertical stability, which may have favored phytoplankton growth, accumulation, or both. Epontic algae released from melting ice may have served as an inoculum for the bloom. Ratios of organic carbon to chlorophyll and biogenic silica to carbon were unusually high, resulting in high biogenic silica concentrations despite only moderately high chlorophyll levels.

Studies on spore release and sporeling growth from carpospores of Gracilaria foliifera (Forsskål) Børgesen var. angustissima (Harvey) Taylor. II. Photosynthetic and respiratory responses

Photosynthetic and respiratory rates were monitored in carposporelings of Gracilaria foliifera (Forsskål) Børgesen var. angustissima (Harvey) Taylor grown on a cross-gradient table using a series of light intensities, temperatures and salinities. Sporelings grown under low light intensity of 17 μE m −2 s −1 showed the highest rate of oxygen production and the highest response to low salinities (10–20 p.p.t.). In part, the responses were influenced by a higher level of chlorophyll a and phycoerythrin: chlorophyll a ratio in sporelings grown under low light intensity. These responses also suggest a tolerance or acclimation to low light conditions, typical of sites of attachment and early growth on subtropical, subtidal rocks in Tampa Bay. Maximum oxygen production occurred at higher temperatures (27.9°C) than maximal growth (25.3°C) of the same sporelings. The highest light level used (80 μE m −2 s −1) did not achieve saturation for photosynthesis, while it appeared to be at saturation level for growth of the same sporelings when expressed by length of sporelings.

Control of iron chlorosis in apple trees with injections of ferrous sulfate and ferric citrate and with soil‐applied iron‐sul

Abstract Chlorotic ‘Red Delicious’ apple (Malus domestica Borkh) trees located in Utah County, Utah, were treated for iron deficiency through pressure injection and soil treatment in September, 1981. Injection treatments were either ferrous sulfate (FeSO4 · 7H2O) or ferric citrate (FeC6H5O7 · H2O) at rates of 100 ml of 1% solution per year of tree age. The soil treatment was surface‐broadcast acidified iron‐rich mining residue (iron‐sul) at approximately 1 kg per year of tree age. Chlorotic conditions were completely eliminated by the spring of 1982 by ferrous sulfate injection. Ferric citrate injection decreased, but did not completely eliminate iron chlorosis. Visual observations were similar in 1983. The iron‐sul treatment gave no apparent improvement of the chlorotic condition in the first season after treatment, and only slight improvement the second year. The improvement in chlorotic conditions gave correspondingly heavier fruit set, higher chlorophyll levels and greater shoot growth for trees injected with both ferrous sulfate and ferric citrate. However, even iron‐sul significantly improved shoot growth and chlorophyll content compared to the untreated control. Some injury at the injection site was observed for both injected compounds.

Effect of Soil PH on Fluridone Activity and Persistence as Determined by Chlorophyll Measurements

Residue levels of fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone} in soil were determined indirectly by measuring the chlorophyll content of wheat (Triticum aestivumL.) grown on a Norfolk sandy loam (Typic paleudult; fine loam, siliceous, thermic) 14, 22, 39, and66days after a preemergence application of the herbicide. The half-life for 0.22 and 0.45 kg/ha of fluridone was estimated to be 18 days. Phytotoxicity increased with increasing pH in newly-treated soils and in soil sampled 14 days after treatment. Higher chlorophyll levels in wheat grown in soil sampled 39 days after fluridone application indicated a decrease in biologically-active herbicide. Soil removed from the field following later cultivation produced small reductions in chlorophyll at pH 4.0 and 5.2, but at pH 7.0 significant fluridone activity was still present in the soil after 66 days. Cultivation may have increased the surface concentration of the herbicide.

Spatio-temporal dynamics of chlorophyll in the open Baltic Sea

Five charts of the chlorophyll and hydrographic fields by vertical profiles of in situ fluorescence and CTD were made on a stationary grid of 20 x 25 nautical miles with a 5-mile spacing in the open Baltic Sea. Both chlorophyll levels and variability were maximal close to the spring bloom. High chlorophyll levels in summer are sustained by recurrent nutrient injections from the deep saline layer. Two of the surveys showed close coupling between the coarse-scale (- 10 km) chlorophyll distri- bution and the hydrographic structure determining the intensity of nutrient transfer. Vigorous advec- tion, stirring and current shear, associated with a strong mesoscale eddy, probably dominated the chlorophyll pattern on three surveys. The upward velocities in the cyclonic eddy resulted in accumula- tion of phytoplankton in the aphotic zone. Intensive heat input from the surface caused a sudden sink- ing of the phytoplankton and the formation of a pronounced sub-surface chlorophyll maximum.

A COMPARATIVE STUDY OF A SALTWATER IMPOUNDMENT AND ITS ADJACENT TIDAL CREEK PERTINENT TO CULTURE OF Crassostrea virginica (GMELIN)

ABSTRACTCertain physical, chemical and biological characteristics associated with the culture of subtidal Crassostrea virginica were assessed in a saltwater impoundment and its adjacent tidal feeder creek. Large seed oysters (initial x̄ = 57.3 mm) were transferred from a polluted estuary of Charleston Harbor to floating, mid‐water, and bottom hardware cloth trays (200/tray) in a 4‐ha pond. Identical trays at comparable depths were placed in the tidal creek and each location was sampled monthly for growth and survival. Surface and bottom water samples were collected weekly throughout the study and hourly during four seasonal 25‐hour stations. Standard hydrographic parameters (temperature, salinity, pH, dissolved oxygen, light penetration, and turbidity) were measured along with chlorophyll a, phytoplankton, dissolved and particulate carbohydrates, nutrients (nitrates, nitrites, orthophosphates and silicates), current velocities, and thioglycollate assays for Perkinsus marinus.Over a 12‐month period, oyster growth was significantly (α = 0.01) greater in the pond than in the creek. Best growth in the impoundment occurred in floating trays, poorest in bottom trays. Growth and survival were higher in winter and lower in summer in both environments. Higher levels of chlorophyll a, carbohydrates, pH, and dissolved oxygen were consistently observed in the impoundment. Lower comparative nutrient values in the pond together with higher biomass levels indicated a more favorable environment for autotrophic production. Greater oyster production in the pond was directly related to a higher instantaneous biomass maintained throughout the year. This relationship was supported by indications of an inverse correlation between nutrient concentrations and the instantaneous biomass. Nutrient and biomass data indicated an apparent NO3‐ limited system.

Physiological response of dwarf wheat to chlorocholinechloride under soil moisture stress

Spraying of CCC (500 ppm) on wheat cv. Kalyan Sona-227 averted the adverse effect of soil moisture stress at the anthesis phase, by maintaining a higher level of chlorophyll, nucleic acids and protein content and acidity of the tissues. Treated plants after recovery from moisture stress yield even more than the untreated plants.

Total glycoalkaloids and chlorophyll in potato cultivars bred in New Zealand

Abstract Mature tubers of the potato cultivars bred at Crop Research Division, DSIR, were assayed for total glycoalkaloid (TGA) content before and after exposure to light, and for chlorophyll content after exposure to light. Tubers were assayed soon after harvest and after storage for 2 and 4 months at 10°c. Although recoveries were somewhat variable, TGA content was generally low but was increased by exposure to light; the levels also increased slightly during storage and the longer tubers were stored the less the increase in response to illumination. Ono was the only cultivar to exceed 20 mg TGA/100 g whole tuber when exposed to light. Differences in chlorophyll accumulation were found, and cultivars which contained high chlorophyll levels were not necessarily those which accumulated most TGA. Chlorophyll accumulation after exposure to light was also less in stored tubers.

Effects of storage treatments upon the ripening of conference pears

AbstractPreliminary work established the pattern of changes in the amounts and properties of soluble pectic polysaccharides in Conference pears during ripening at 10 °C.Conference pears were harvested on three dates and stored in air at −1 °C and in 2% O2 at −1 °C for various periods. They were ripened on removal from store at 18 °C. Chlorophyll and carotenoid concentrations in the fruit peel and soluble polyuronide concentrations in whole fruit as well as general storage data were recorded.The lag in the ripening of pears at 18 °C after harvesting was abolished by storage at −1 °C. Softening and pectin changes were similar in all stored fruit samples irrespective of picking date, period of storage and whether stored in air or 2% O2. Storage in 2% O2 did retard breakdown slightly, however.The main effect of 2% O2 was that it reduced the rate of destruction of chlorophyll during storage. Higher levels of chlorophyll were found during ripening in fruit which had been stored in 2% O2 than in fruit stored in air.

Retardation of leaf senescence by benzyladenine in intact bean plants

Benzyladenine (BA) applied to primary leaves of intact bean plants delayed the senescence of both the leaves and the entire shoot. The retardation of senescence was manifested in higher levels of chlorophyll, protein, RNA and ribonuclease activity at all stages of development. Also, the levels of incorporation of labelled precursors into protein and RNA were enhanced. The effect of BA was largely independent of light intensity and the compound did not act merely as a nitrogen source.