scholarly journals Photosynthesis and Respiration by the Flag Leaf and Components of the Ear During Grain Development In Wheat

1970 ◽  
Vol 23 (2) ◽  
pp. 245 ◽  
Author(s):  
LT Evans ◽  
HM Rawson
Keyword(s):  
Light Intensity ◽  
Dark Respiration ◽  
Flag Leaf ◽  
Gas Analysis ◽  
Constant Light ◽  
Grain Development ◽  
Flag Leaves ◽  
Photosynthesis And Respiration

Rates of photosynthesis and dark respiration of the ears and flag leaves of three varieties of wheat grown at 21 DC under a constant light intensity of 3200 f.c. were measured by infrared gas analysis twice weekly throughout the period of grain development. Measurements were made on both the intact ears and the separated grains and ear structures, in air and in a mixture of nitrogen plus 320 p.p.m. C02. Dry weights of the grains, ears, and main stems were also determined.

The effect of some environmental factors on the growth of young aspen trees (Populus tremuloides) in controlled environments

1971 ◽  
Vol 49 (8) ◽  
pp. 1443-1453 ◽  
Author(s):  
G. C. Bate ◽  
D. T. Canvin
Keyword(s):  
Light Intensity ◽  
Photosynthetic Rate ◽  
Populus Tremuloides ◽  
Dark Respiration ◽  
Continuous Light ◽  
Carbon Gain ◽  
Fluorescent Light ◽  
Controlled Environment ◽  
Rate Of Photosynthesis ◽  
Photosynthesis And Respiration

Several populations (each of 32 trees) of young aspen trees (Populus tremuloides Michx) were allowed to break from dormancy in controlled environment cabinets. The rate of photosynthesis and dark respiration and the rate of carbon gain (as difference between photosynthesis and respiration) of the population as affected by photoperiod duration, light intensity, and day/night temperatures was determined by measuring the CO2 exchange of the whole population using the controlled environment cabinet as the plant chamber.The rates of photosynthesis of the plants were similar during both 12- or 18-h photoperiods. The rates of respiration during the corresponding night periods were also similar. In continuous light the photosynthetic rate remained unchanged if growth (expansion of new leaves) was rapid. During periods of slower growth, the photosynthetic rate in continuous light was reduced. In spite of this reduction in the rate of photosynthesis, carbon gain was still greatest under continuous light.In the day/night temperature study, the largest gains in carbon per day by the aspen trees were obtained at day/night temperatures of 15/10 °C or 15/15 °C. Higher day or night temperatures resulted in decreased rates of carbon gain.Increased light intensity from fluorescent lamps resulted in increased rates of photosynthesis. Addition of incandescent light to the fluorescent light resulted, in almost all cases, in decreased rates of photosynthesis. This may, in part, be due to effects on leaf temperature.Photosynthesis of the populations was usually maximal at the beginning of the photoperiod and decreased steadily during the photoperiod. The rate of decrease was directly related to the rate of photosynthesis at the beginning of the photoperiod.Both photosynthesis and respiration were affected by temperature and light but no clear relationship existed between the rate of CO2 exchange during the photoperiod and that during the nyctoperiod following.

scholarly journals Effects of Independent and Combined Water-Deficit and High-Nitrogen Treatments on Flag Leaf Proteomes during Wheat Grain Development

2020 ◽  
Vol 21 (6) ◽  
pp. 2098 ◽  
Author(s):  
Dong Zhu ◽  
Gengrui Zhu ◽  
Zhen Zhang ◽  
Zhimin Wang ◽  
Xing Yan ◽  
...  
Keyword(s):  
Carbohydrate Metabolism ◽  
Water Deficit ◽  
Flag Leaf ◽  
Redox Homeostasis ◽  
Combined Treatment ◽  
Proteome Analysis ◽  
N Fertilization ◽  
Grain Development ◽  
High Nitrogen ◽  
Nitrogen Treatments

We present the first comprehensive proteome analysis of wheat flag leaves under water-deficit, high-nitrogen (N) fertilization, and combined treatments during grain development in the field. Physiological and agronomic trait analyses showed that leaf relative water content, total chlorophyll content, photosynthetic efficiency, and grain weight and yield were significantly reduced under water-deficit conditions, but dramatically enhanced under high-N fertilization and moderately promoted under the combined treatment. Two-dimensional electrophoresis detected 72 differentially accumulated protein (DAP) spots representing 65 unique proteins, primarily involved in photosynthesis, signal transduction, carbohydrate metabolism, redox homeostasis, stress defense, and energy metabolism. DAPs associated with photosynthesis and protein folding showed significant downregulation and upregulation in response to water-deficit and high-N treatments, respectively. The combined treatment caused a moderate upregulation of DAPs related to photosynthesis and energy and carbohydrate metabolism, suggesting that high-N fertilization can alleviate losses in yield caused by water-deficit conditions by enhancing leaf photosynthesis and grain storage compound synthesis.

scholarly journals Photosynthesis of Tropical Pasture Plants III. Leaf Age

1971 ◽  
Vol 24 (4) ◽  
pp. 1077 ◽  
Author(s):  
MM Ludlow ◽  
GL Wilson
Keyword(s):  
Dark Respiration ◽  
Leaf Age ◽  
Gas Analysis ◽  
Controlled Environment ◽  
Tropical Pasture ◽  
Optimum Conditions ◽  
Dark Respiration Rate ◽  
Leaf Ontogeny ◽  
Analysis System ◽  
Pasture Plants

Grass and legume plants were grown under near-optimum conditions in controlled-environment cabinets. Changes in net photosynthetic rate, dark respiration rate, and carbon dioxide transfer resistances during leaf ontogeny, and variability between leaves on grass tillers and legume runners were studied under controlled conditions in an open gas analysis system.

scholarly journals On the Minimum Quantum Requirement of Photosynthesis

2009 ◽  
Vol 64 (9-10) ◽  
pp. 673-679 ◽  
Author(s):  
Yuzeir Zeinalov
Keyword(s):  
Light Intensity ◽  
Oxygen Evolution ◽  
Quantum Efficiency ◽  
Optical Density ◽  
Dark Respiration ◽  
Linear Part ◽  
Light Curves ◽  
Quantum Requirement ◽  
Light Intensities ◽  
Maximum Quantum Efficiency

An analysis of the shape of photosynthetic light curves is presented and the existence of the initial non-linear part is shown as a consequence of the operation of the non-cooperative (Kok’s) mechanism of oxygen evolution or the effect of dark respiration. The effect of nonlinearity on the quantum efficiency (yield) and quantum requirement is reconsidered. The essential conclusions are: 1) The non-linearity of the light curves cannot be compensated using suspensions of algae or chloroplasts with high (>1.0) optical density or absorbance. 2) The values of the maxima of the quantum efficiency curves or the values of the minima of the quantum requirement curves cannot be used for estimation of the exact value of the maximum quantum efficiency and the minimum quantum requirement. The estimation of the maximum quantum efficiency or the minimum quantum requirement should be performed only after extrapolation of the linear part at higher light intensities of the quantum requirement curves to “0” light intensity

Thermal acclimation of respiration but not photosynthesis in Pinus radiata

2008 ◽  
Vol 35 (6) ◽  
pp. 448 ◽  
Author(s):  
Lai Fern Ow ◽  
David Whitehead ◽  
Adrian S. Walcroft ◽  
Matthew H. Turnbull
Keyword(s):  
Pinus Radiata ◽  
Growth Temperature ◽  
Dark Respiration ◽  
Temperature Acclimation ◽  
Short Term ◽  
Photosynthesis And Respiration ◽  
Term Response ◽  
N Status ◽  
Respiratory Responses

Pinus radiata L. were grown in climate-controlled cabinets under three night/day temperature treatments, and transferred between treatments to mimic changes in growth temperature. The objective was to determine the extent to which dark respiration and photosynthesis in pre-existing and new needles acclimate to changes in growth temperatures. We also assessed whether needle nitrogen influenced the potential for photosynthetic and respiratory acclimation, and further assessed if short-term (instantaneous, measured over a few hours) respiratory responses are accurate predictors of long-term (acclimated, achieved in days–weeks) responses of respiration to changing temperature. Results show that respiration displayed considerable potential for acclimation. Cold and warm transfers resulted in some acclimation of respiration in pre-existing needles, but full acclimation was displayed only in new needles formed at the new growth temperature. Short-term respiratory responses were poor predictors of the long-term response of respiration due to acclimation. There was no evidence that photosynthesis in pre-existing or new needles acclimated to changes in growth temperature. N status of leaves had little impact on the extent of acclimation. Collectively, our results indicate that there is little likelihood that respiration would be significantly stimulated in this species as night temperatures increase over the range of 10–20°C, but that inclusion of temperature acclimation of respiration would in fact lead to a shift in the balance between photosynthesis and respiration in favour of carbon uptake.

Productivity of Vegetable Crops in a Region of High Solar Input. III. Carbon Balance of Potato Crops

1974 ◽  
Vol 1 (2) ◽  
pp. 283 ◽  
Author(s):  
PJM Sale
Keyword(s):  
Carbon Balance ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Gas Analysis ◽  
Co2 Uptake ◽  
Co2 Efflux ◽  
Vegetable Crops ◽  
Weight Changes ◽  
Potato Crops

The carbon balance of potato crops has been studied by measuring canopy net photosynthesis and dark respiration losses with a field assimilation chamber and semi-closed gas analysis system. Results are given for the latter part of growth in both a spring-planted and a summer-planted crop. Net CO2 uptake increased with solar input to reach 35–40mg dm-2 (ground area) h-1 at 400–450 W m-2, but light saturation then occurred and little or no further uptake resulted from increases in solar input up to 1000 W m-2. This supports the previous conclusion that net photosynthesis in the potato is determined by the size of the 'sink' provided by the developing tubers. The imposed experimental variables of reduced solar input (21 and 34% shade) and soil moisture were found not to affect the relation between solar input and CO2 uptake, and the effect of chamber temperature was also very small. Dark respiration rates of the canopy were markedly sensitive to temperature, and also to the solar input prior to measurement. Respiration from the below-ground plant parts accounted for a considerable part of the total plant respiration. In all, 15–20 % of the net assimilation during daylight hours was lost by night respiration. There was little variation in CO2 efflux from uncropped soil during the experiments. Dry weight changes calculated from the gasometric measurements were in accordance with those found from previous growth analysis. * Part II, Aust. J. Agric. Res., 1973, 24, 751–62.

Productivity of Vegetable Crops in a Region of High Solar Input. IV. Field Chamber Measurements on French Beans (Phaseolus vulgaris L.) And Cabbages (Brassica oleracea L.)

1975 ◽  
Vol 2 (4) ◽  
pp. 461 ◽  
Author(s):  
PJM Sale
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Dark Respiration ◽  
Gas Analysis ◽  
Large Field ◽  
Co2 Uptake ◽  
Vegetable Crops ◽  
Area Index ◽  
French Beans

Net CO2 uptakes have been measured for crop canopies of French beans and cabbages, sown at two plant densities, using a large field assimilation chamber and a semi-closed gas-analysis system. For both species, the maximum rates of uptake were a little less than 40 mg CO2 dm-2 (ground area) h-1, and light saturation of the canopy occurred at 600-650 W m-2 (French beans) or about 800 W m-2 (cabbages). Net CO2 uptake decreased with leaf area index at values below about 5, but was relatively insensitive to temperature over the range used. Once this leaf area index was reached, the relationship between net uptake and solar radiation remained fairly constant throughout the growth period. For both species, dark respiration rates were markedly dependent on temperature, and also were lower at night than during the day when measured at the same temperature. For both French beans and cabbages, growth analyses showed the maximum growth rates to be 18-19 g dry weight m-2 (ground area) day-1. The mean growth rate from emergence to harvest for an overwintered cabbage crop was 5.5 g m-2 day-1. It is suggested that the main advantage of the region in terms of plant productivity lies in the long frost-free growing season and the ability of frost-tolerant crops to maintain fairly high growth rates throughout a mild and comparatively sunny winter.

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