scholarly journals Photosynthesis by Thin Leaf Slices in Solution I. Properties of Leaf Slices and Comparison With Whole Leaves

1973 ◽  
Vol 26 (1) ◽  
pp. 15 ◽  
Author(s):  
HG Jones ◽  
CB Osmond

The preparation and photosynthetic properties of thin leaf slices from several plants were examined. Photosynthesis was measured either as oxygen evolution in a polarographic electrode, or as 14C02 fixation. Oxygen uptake in the dark gave a measure of the dark respiration rate.

2014 ◽  
Vol 40 (1) ◽  
pp. 14-17 ◽  
Author(s):  
Ye. N. Baranova ◽  
E. N. Akanov ◽  
A. A. Gulevich ◽  
L. V. Kurenina ◽  
S. A. Danilova ◽  
...  

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1317
Author(s):  
Subang An ◽  
Xingtu Liu ◽  
Bolong Wen ◽  
Xiaoyu Li ◽  
Peng Qi ◽  
...  

Water shortages have an important impact on the photosynthetic capacity of Phragmites australis. However, this impact has not been adequately studied from the perspective of photosynthesis. An in-depth study of the photosynthetic process can help in better understanding the impact of water shortages on the photosynthetic capacity of P. australis, especially on the microscale. The aim of this study is to explore the photosynthetic adaptation strategies to environmental changes in saline‒alkaline wetlands. The light response curves and CO2 response curves of P. australis in five habitats (hygrophilous, xerophytic, psammophytic, abandoned farmland, paddy field drainage) in saline‒alkaline wetlands were measured at different stages of their life history, and we used a nonrectangular hyperbolic model to fit the data. It was concluded that P. australis utilized coping strategies that differed between the growing and breeding seasons. P. australis in abandoned farmland during the growing season had the highest apparent quantum efficiency (AQE) and photosynthetic utilization efficiency for weak light because of the dark environment. The dark respiration rate of P. australis in the drainage area of paddy fields was the lowest, and it had the highest values for photorespiration rate, maximum photosynthetic rate (Pmax), photosynthetic capacity (Pa), biomass, maximum carboxylation rate (Vcmax), and maximum electron transfer rate (Jmax). The light insensitivity of P. australis increased with the transition from growing to breeding season, and the dark respiration rate also showed a downward trend. Moreover, Vcmax and Jmax would decline when Pmax and Pa showed a declining trend, and vice versa. In other words, Vcmax and Jmax could explain changes in the photosynthetic capacity to some extent. These findings contribute to providing insights that Vcmax and Jmax can directly reflect the variation in photosynthetic capacity of P. australis under water shortages in saline‒alkaline wetlands and in other parts of world where there are problems with similarly harmful environmental conditions.


1977 ◽  
Vol 4 (1) ◽  
pp. 159 ◽  
Author(s):  
S Fukai ◽  
JH Silsbury

The rates of dark respiration of subterranean clover communities, grown at 12, 16, 20 and 24°C in naturally lit temperature-controlled glasshouses, were measured several times during growth. The dark respiration rate, measured at growth temperature, increased linearly with increase in plant dry matter for each temperature and it increased approximately linearly with increase in temperature at a given dry matter. A low crop growth rate shown by communities with dry matter greater than 300 g m-2 at a temperature of 24°C was largely accounted for by a high respiration rate. The temperature coefficient of dark respiration (Q10) was inversely related to growth temperature. Dark respiration rate at 28°C was lower for communities grown at 24°C than for communities grown at 12 or 16°C when the comparison was made at the same dry matter. Calculated dark respiration rate from shoot dry matter, growth temperature and current measured temperature was close to the measured rate, indicating the dark respiration rate of subterranean clover communities to be largely accounted for by these factors. Use of an integrated form of a growth equation and allowing for dark efflux shows, on a 12 hour day, the rate of dry matter accumulation at 24°C to be the same as that at 12°C.


1940 ◽  
Vol 24 (1) ◽  
pp. 45-67 ◽  
Author(s):  
Jack Myers ◽  
G. O. Burr

1. The effect on oxygen evolution of Chlorella vulgaris produced by light intensities up to about 40,000 f.-c. has been studied by the use of the Warburg technique. 2. Above a certain critical intensity, which is determined by the previous history of the cells, the rate of oxygen evolution decreases from the maximum to another constant rate. This depression is at first a completely reversible effect. 3. With a sufficiently high intensity this constant rate represents an oxygen uptake greater than the rate of dark respiration. During such a constant rate of oxygen uptake a progressive injury to the photosynthetic mechanism takes place. After a given oxygen consumption the rate falls off, approaching zero, and the cells are irreversibly injured. 4. The constant rate of oxygen evolution (2 and 3) decreases in a continuous manner with increasing light intensities, approaching a value which is approximately constant for all lots of cells regardless of previous history. 5. Two alternative hypotheses have been presented to explain the observed phenomena. The more acceptable of these proposes quick inactivation of the photosynthetic mechanism, the extent of inhibition depending on the light intensity. 6. In Chlorella vulgaris solarization is influenced by the previous history of the cells.


1990 ◽  
Vol 66 (6) ◽  
pp. 649-654 ◽  
Author(s):  
D. Y. RAINEY ◽  
J. B. MITTON ◽  
R. K. MONSON ◽  
D. WILSON

Weed Science ◽  
1987 ◽  
Vol 35 (2) ◽  
pp. 141-144 ◽  
Author(s):  
G. Rajendrudu ◽  
J. S. Rama Prasad ◽  
V. S. Rama Das

The rates of foliar dark respiration and net photosynthesis in attached leaves of 25 C3, C4, and C3-C4 intermediate dicotyledonous weed species were determined using the infrared gas analyzer. The ratio of dark respiration to photosynthesis per unit leaf area in attached leaves of each species was inversely proportional to leaf age. Highly significant, positive linear correlation was observed between the rates of foliar dark respiration and net photosynthetic CO2 uptake in dicot weeds irrespective of the photosynthetic type. The higher foliar dark respiration rate found in some of the weed species can be attributed in part to the higher carbohydrate levels as generated by a rapid photosynthetic CO2 assimilation. The significance of higher dark respiration rate in relation to carbon and energy economy of weeds is discussed.


HortScience ◽  
1994 ◽  
Vol 29 (12) ◽  
pp. 1456-1459 ◽  
Author(s):  
M. Hossein Behboudian ◽  
Robert Lai

Responses of the tomato (Lycopersicon esculentum Mill. cv. Virosa) plant to elevated CO2 concentrations applied throughout the photoperiod or part of it were studied under two temperature regimes. Plants were exposed to CO2 at 340 (control), 700, and 1000 μl·liter–1. The highest concentration was applied only at 22/16C (day/night) and 700 μl·liter–1 at 22/16C and 25/16C. Transpiration rates were lower and photosynthetic rates were higher under elevated CO2 than at the ambient level. Biomass production was higher only for plants grown at 700 μl·liter–1 and 25/16C. Concentrations of macronutrients were lower in plants exposed to 1000 μl CO2/liter than in the control plants. Intermittent CO2 was applied using two timing methods. In method 1, plants were exposed to 4- or 8-hour high-CO2 concentrations during their 12-hour photoperiod. In method 2, plants were exposed for 3.5 days of each week to 700 μl CO2/liter. Only two of the 8-hour exposures resulted in greater growth than the controls. The lack of higher growth for CO2-enriched plants at 22/16C was attributed to a higher dark respiration rate and to a lack of efficient transport of photosynthates out of leaves.


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