The effect of rapidly changing light on the rate of photosynthesis in largetooth aspen (Populus grandidentata)

1970 ◽  
Vol 48 (4) ◽  
pp. 823-829 ◽  
Author(s):  
D. F. W. Pollard
Keyword(s):  
Bright Light ◽  
Net Photosynthesis ◽  
Ventilation Rate ◽  
Light Regimes ◽  
Fluctuating Irradiance ◽  
Rate Of Photosynthesis ◽  
Light Flecks ◽  
Four Levels ◽  
Forest Floors ◽  
Changing Light

Net photosynthesis by largetooth aspen was measured at each of four levels of irradiance, 3.4, 8.2, 22.6 and 73.1 W m−2 (0.4–0.7 μ), and during interchange of equal periods of these same levels. The periods between interchange ranged from about 0.2 to 300 s. All measurements were made between 17 and 19 °C; ventilation rate across leaves was equivalent to 1.5 m s−1. Photosynthesis was lower during interchange of long periods; depending on the irradiance levels selected, shorter periods led to increases in photosynthesis of up to 50%. Sometimes a recovery in photosynthesis occurred with the longest periods. The greatest changes were observed when one irradiance sequence was well below saturation level and the other was at or above saturation. Measurements of light regimes in three forest types showed that, during moderate winds at least, fluctuations with periods of between 0.1 and 100 s are commonplace. However, the effects of fluctuating irradiance on net photosynthesis may be important for growth and regeneration only where canopy height and spacings result in bright light flecks on other wise dark forest floors.

scholarly journals A Persistent Daily Rhythm in Photosynthesis

1961 ◽  
Vol 45 (1) ◽  
pp. 69-76 ◽  
Author(s):  
J. Woodland Hastings ◽  
Lazarus Astrachan ◽  
Beatrice M. Sweeney
Keyword(s):  
Cell Division ◽  
Diurnal Rhythm ◽  
Maximum Rate ◽  
Photosynthetic Capacity ◽  
Bright Light ◽  
Light Period ◽  
Daily Rhythm ◽  
Single Mechanism ◽  
Rate Of Photosynthesis ◽  
Dim Light

The luminescent marine dinoflagellate, Gonyaulax polyedra, exhibits a diurnal rhythm in the rate of photosynthesis and photosynthetic capacity measured by incorporation of C14O2, at different times of day. With cultures grown on alternating light and dark periods of 12 hours each, the maximum rate is at the 8th hour of the light period. Cultures transferred from day-night conditions to continuous dim light continue to show the rhythm of photosynthetic capacity (activity measured in bright light) but not of photosynthesis (activity measured in existing dim light). Cultures transferred to continuous bright light, however, do not show any rhythm. Several other properties of the photosynthetic rhythm are similar to those of previously reported rhythms of luminescence and cell division. This similarity suggests that a single mechanism regulates the various rhythms.

The mathematical model as an aid to developing concepts concerning the soil-atmosphere-crop relation

1990 ◽  
Vol 329 (1255) ◽  
pp. 357-360
Keyword(s):  
Absorption Rate ◽  
Net Photosynthesis ◽  
Organic Content ◽  
Nutrient Level ◽  
Soil Organisms ◽  
Root:Shoot Ratio ◽  
Crop Growth Rate ◽  
The Mathematical Model ◽  
Kinetics Of ◽  
Changing Light

The relation between light absorption rate and crop growth rate may be deduced from the kinetics of net photosynthesis showing that for a crop, such as winter wheat, growing from winter to summer this relation must be S-shaped. Altering the soil-solution nutrient level changes, in an opposite sense, the root:shoot ratio, thereby changing light interception. Destruction of live roots by soil organisms by increasing root growth enhances the long-life organic content of the soil. The relation between growth of the plant and the growth of seeds or tubers on the plant is determined by their relative competitive strengths for attracting nutrients.

scholarly journals Ontogeny of Photosynthetic Performance in Fragaria virginiana under Changing Light Regimes

1979 ◽  
Vol 63 (3) ◽  
pp. 542-547 ◽  
Author(s):  
Thomas W. Jurik ◽  
Jean F. Chabot ◽  
Brian F. Chabot
Keyword(s):  
Photosynthetic Performance ◽  
Light Regimes ◽  
Fragaria Virginiana ◽  
Changing Light

Effect of changes in carbohydrate concentration on the rate of net photosynthesis in mature leaves of Abies balsamea

1973 ◽  
Vol 51 (4) ◽  
pp. 751-758 ◽  
Author(s):  
C. H. A. Little ◽  
K. Loach
Keyword(s):  
Photosynthetic Rate ◽  
Abies Balsamea ◽  
Net Photosynthesis ◽  
Total Sugar ◽  
Starch Accumulation ◽  
Carbohydrate Concentration ◽  
Normal Period ◽  
Before And After ◽  
Rate Of Photosynthesis ◽  
Foliar Concentration

The hypothesis that photosynthate accumulation within a leaf inhibits the ongoing rate of photosynthesis was investigated in 6-year-old balsam fir trees. Rates of net photosynthesis and transpiration, and concentrations of starch, total sugar, chlorophyll, and water were measured in 1-year-old or fully expanded, current needles, and leaf resistances to carbon dioxide transfer were calculated. The several-fold rise and fall in the content of carbohydrate (mostly starch) that occurs naturally in 1-year-old needles before and after budbreak was correlated positively rather than negatively with the photosynthetic rate. Shading during the normal period of starch accumulation decreased the concentrations of both starch and total sugar, but did not increase photosynthesis. Continuous cooling of the base of a branch to 2 °C to inhibit translocation of photosynthate did not affect the photosynthetic rate during a 2-week period, nor did it cause carbohydrate accumulation, as measured at the end of the experiment. Removing a ring of bark from a branch base resulted in a large increase in the foliar concentration of starch (but not total sugar) and a small decrease in photosynthesis. However, the concomitant decrease in moisture content, not the accumulation of starch, was more probably the cause of the reduced photosynthesis. We conclude that the rate of photosynthesis in fir needles, at least under normal growing conditions, is not influenced by photosynthate accumulation.

scholarly journals Interactive Effects of Drought and Saline Aerosol Stress on Morphological and Physiological Characteristics of Two Ornamental Shrub Species

Horticulturae ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 517
Author(s):  
Stefania Toscano ◽  
Antonio Ferrante ◽  
Daniela Romano ◽  
Alessandro Tribulato
Keyword(s):  
Sea Water ◽  
Net Photosynthesis ◽  
Interactive Effects ◽  
Total Biomass ◽  
Experimental Conditions ◽  
Relative Water ◽  
Effects Of Drought ◽  
Four Levels ◽  
Almost All ◽  
Ornamental Shrubs

Effects of drought and aerosol stresses were studied in a factorial experiment based on a Randomized Complete Design with triplicates on two ornamental shrubs. Treatments consisted of four levels of water container (40%, 30%, 20%, and 10% of water volumetric content of the substrate) and, after 30 days from experiment onset, three aerosol treatments (distilled water and 50% and 100% salt sea water concentrations). The trial was contextually replicated on two species: Callistemon citrinus (Curtis) Skeels and Viburnum tinus L. ‘Lucidum’. In both species, increasing drought stress negatively affected dry biomass, leaf area, net photosynthesis, chlorophyll a fluorescence, and relative water content. The added saline aerosol stress induced a further physiological water deficit in plants of both species, with more emphasis on Callistemon. The interaction between the two stress conditions was found to be additive for almost all the physiological parameters, resulting in enhanced damage on plants under stress combination. Total biomass, for effect of combined stresses, ranged from 120.1 to 86.4 g plant−1 in Callistemon and from 122.3 to 94.6 g plant−1 in Viburnum. The net photosynthesis in Callistemon declined by the 70% after 30 days in WC 10% and by the 45% and 53% in WC 20% and WC 10% respectively after 60 days. In Viburnum plants, since the first measurement (7 days), a decrease of net photosynthesis was observed for the more stressed treatments (WC 20% and WC 10%), by 57%. The overall data suggested that Viburnum was more tolerant compared the Callistemon under the experimental conditions studied.

scholarly journals Sequential Path Model for Grain Yield in Soybean

2010 ◽  
Vol 2 (3) ◽  
pp. 104-109
Author(s):  
Mohammad SEDGHI ◽  
Bahman AMANPOUR-BALANEJI
Keyword(s):  
Grain Yield ◽  
Path Analysis ◽  
Net Photosynthesis ◽  
Path Model ◽  
Physiological Traits ◽  
Research Station ◽  
Third Order ◽  
Area Index ◽  
Four Levels ◽  
Intercepted Radiation

This study was performed to determine some physiological traits that affect soybean,s grain yield via sequential path analysis. In a factorial experiment, two cultivars (Harcor and Williams) were sown under four levels of nitrogen and two levels of weed management at the research station of Tabriz University, Iran, during 2004 and 2005. Grain yield, some yield components and physiological traits were measured. Correlation coefficient analysis showed that grain yield had significant positive and negative association with measured traits. A sequential path analysis was done in order to evaluate associations among grain yield and related traits by ordering the various variables in first, second and third order paths on the basis of their maximum direct effects and minimal collinearity. Two first-order variables, namely number of pods per plant and pre-flowering net photosynthesis revealed highest direct effect on total grain yield and explained 49, 44 and 47 % of the variation in grain yield based on 2004, 2005, and combined datasets, respectively. Four traits i.e. post-flowering net photosynthesis, plant height, leaf area index and intercepted radiation at the bottom layer of canopy were found to fit as second-order variables. Pre- and post-flowering chlorophyll content, main root length and intercepted radiation at the middle layer of canopy were placed at the third-order path. From the results concluded that, number of pods per plant and pre-flowering net photosynthesis are the best selection criteria in soybean for grain yield.

Effect of soil salinity on stomatal conductance and photosynthesis of green ash (Fraxinuspennsylvanica)

1986 ◽  
Vol 16 (3) ◽  
pp. 569-573 ◽  
Author(s):  
S. R. Pezeshki ◽  
J. L. Chambers
Keyword(s):  
Stomatal Conductance ◽  
Soil Salinity ◽  
Saline Water ◽  
Salt Water ◽  
Net Photosynthesis ◽  
Green Ash ◽  
Long Term Effects ◽  
Seedling Mortality ◽  
Oil Drilling ◽  
Four Levels

Seedlings of green ash (Fraxinuspennsylvanica Marsh.) were subjected to four levels of salt water ranging from approximately seawater concentration to one-tenth the concentration of seawater to simulate a temporary intrusion of salt water in coastal areas and brine spills associated with oil-drilling activities. The effect of saltwater influx on subsequent stomatal behaviour and net photosynthesis was studied. Stomatal conductance was reduced up to 72% and net photosynthesis declined by as much as 86% in response to the application of saline water. Both responses were rapid and occurred shortly after treatment. In addition to substantial declines in stomatal conductance and net photosynthesis, plant water potential also declined after treatment. All levels of salt application resulted in leaf injury and the two highest concentrations caused rapid seedling mortality. The results of this study indicate that green ash seedlings are extremely sensitive to soil salinity and will not survive either saltwater intrusion or brine spills associated with oil-drilling activities. Potential long-term effects are discussed.

scholarly journals Soil and Grassland Effects on Grassland Net Photosynthesis in Gannan, China, from 2000 to 2018

2021 ◽  
Author(s):  
Stephen Nazieh ◽  
Meiling Zhang
Keyword(s):  
Net Photosynthesis ◽  
Growing Season ◽  
Significant Difference ◽  
Increasing Trend ◽  
Broad Leaf ◽  
Rate Of Photosynthesis ◽  
The Difference ◽  
Study Sites ◽  
Grassland Types ◽  
The Ideal

What is the ideal soil-grass combination for maximum photosynthesis? In this study, we investigated how soil and grassland types affect photosynthesis in the grasslands of Gannan, China. We divided the grasslands of Gannan into 166 study sites, each with a unique soil-grass combination by intersecting the soil and ecoregion maps using ArcGIS. We obtained 19 years of data on the Net Photosynthesis (PsnNet) of grasslands in the area from 2000 to 2018 and then divided them into “growing season” (June to September) and “non-growing season” (October top May). Between 2000 and 2018, PsnNet of grasslands showed a gradually increasing trend. The effect of soil type on PsnNet was not significant during the growing season. However, it was highly significant during the non-growing season. Among the soil types, grasses that grew in Mollic, Gelic, and Haplic soils had the highest rate of photosynthesis. The difference in PsnNet among the various grass types was highly significant during both seasons. However, Tropical and Subtropical succulent evergreen broad-leaf shrubs and Temperate meadows had the highest rate of photosynthesis. Additionally, there was a highly significant difference in PsnNet among the various soil-grass interactions. In the growing season, TStEgBLS growing Eutric soils had the highest PsnNet. However, SaDBLS growing in Gelic soils had the the highest.

Gas Exchange of Mitchell Grass (Astrebla lappacea (Lindl.) Domin) in Relation to Irradiance, Carbon Dioxide Supply, Leaf Temperature and Temperature History

1976 ◽  
Vol 3 (4) ◽  
pp. 471 ◽  
Author(s):  
D Doley ◽  
DJ Yates
Keyword(s):  
Dark Respiration ◽  
Leaf Age ◽  
Net Photosynthesis ◽  
Co2 Concentration ◽  
Light Level ◽  
Leaf Temperature ◽  
Temperature History ◽  
The Best Approximation ◽  
Growth Regime ◽  
Rate Of Photosynthesis

Relationships were established between photosynthesis in A. lappacea and photosynthetic quantum flux, ambient CO2 concentration and leaf temperature. There were no substantial differences between plants raised in a glasshouse and under three temperature regimes in growth cabinets in their responses to light level and CO2 concentration. Large variations in the rate of photosynthesis were observed in plants raised under any environmental regime, this being due in part to the effects of leaf age. It was concluded that the greatest rate of photosynthesis observed in a series of experiments represented the best approximation to the rate attainable in the absence of limitations imposed by factors extraneous to the experiment concerned. The temperature responses of net photosynthesis, dark respiration and transpiration were influenced by growth regime temperature; the leaf temperature at which photosynthesis was maximal increased with growth regime air temperature up to at least 33°C. Plants transferred from one temperature regime to another exhibited the behaviour characteristic of the new regime within one day and two nights of the transfer. Estimates of gas diffusive resistances indicated that both the stornatal and CO2 mesophyll (residual) resistances adapted to changed temperature conditions after about one thermoperiod. The temperatures at which these diffusive resistances were minimal varied in the same sense as the changes in growth regime temperature. The roles of these aspects of behaviour in the adaptation of A. lappacea to its environment are discussed.

scholarly journals Effect of Paclobutrazol Treatment on Some Leaf Physiological and Biochemical Characteristics of Rejuvenated Coffee (Coffea arabica L.) Trees

2016 ◽  
pp. 74-82
Author(s):  
Arsenio Ramos
Keyword(s):  
Chlorophyll Content ◽  
Transpiration Rate ◽  
Net Photosynthesis ◽  
Physiological And Biochemical Characteristics ◽  
Co Concentration ◽  
Rate Of Photosynthesis ◽  
Physiological And Biochemical ◽  
Coffea Arabica L ◽  
Treatment Application ◽  
Leaf N

Rejuvenation pruning has been proven effective in bringing back vigor and productivity of old coffee trees. The effectiveness of the present rejuvenation techniques however could be probably enhanced by the application of tree growth regulators with known reinvigorating or tree health enhancing effect such as Paclobutrazol but has not been tried so far. The present study aimed to evaluate some physiological and biochemical responses of the rejuvenated coffee trees to timing and level of PBZ application prior to cutting. Plants applied with PBZ 2 months prior to pruning had higher leaf internal CO concentration compared to those applied 1 month prior to 2 pruning. Net photosynthesis, transpiration rate, PAR/LAI, chlorophyll content, and leaf N, P, K, Ca and Mg contents did not differ with time of PBZ treatment. Application of 0.5-1.0 g a.i. PBZ per meter canopy span significantly increased transpiration rate, internal COconcentration and 2 chlorophyll content but did not affect the rate of photosynthesis, PAR/LAI, leaf N, P, K, Ca and Mg contents.

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