Photosynthesis canopy

Sellers, P. J., Berry, J. A., Collatz, G. ]., Field, C. B. and Hall, F. G. (1992). Canopy reflectance, photosynthesis, and transpiration. III. A reanalysis using improved leaf models and a new canopy integration scheme. Remote Sens. Environ. 42,187-216. 

In certain plant habitats or niches, access to resources depends crucially upon rapid growth under conditions of climatic stress. Examples of this phenomenon are particularly obvious on shallow soils in continental climates where the growth window between winter cold and summer desiccation may be extremely short. In deciduous woodlands in the cool temperate zone an essentially similar niche arises in the period between snow melt and closure of the tree canopy. Both circumstances provide opportunities for high rates of photosynthesis and mineral nutrient capture in the late spring but depend upon rapid expansion of roots and shoots in the low-temperature conditions of the late winter and early spring. 

Given these restrictions, oat, barley and alfalfa canopies required treatments with more than 1 pphm HF, about 5 pphm O3 or CI2, 20 pphm SO2, and 40-60 pphm NO2 or NO before apparent photosynthesis rates were measurably depressed by the end of 2 hr of exposure. Above these apparent threshold values the 2-hr depressions induced were linearly related to pollutant concentrations applied up to those that caused visible foliar injury to the tissues. Foliar necrosis occurred to some plant tissues within the canopies exposed to approximately 15 pphm HF,... 

Although information concerning the inhibition of photosynthesis by air pollution is limited, we may gain perspective into the potential problem through appraising available data on the extent that CO2 uptake by oats, barley, and alfalfa canopies can be suppressed by short-term (a few hours) exposure to the major air pollutants and simple combinations investigated. 

Stutte, G. W., Monje, O., Goins, G., Tripathy, B. C. (2005). Mierogravity effects on thylakoid, single leaf, and whole canopy photosynthesis of dwarf wheat. Planta, 223,46-56. 

Figure 4. Seasonal changes in available carbohydrates in a Californian evergreen oak (A), a Vermont sugar maple (B), arul a Californian buckeye (C). Maple data for sapwood are from Ref. 15, Oak and buckeye data are from Ref. 49, for total branch minus fruits. The evergreen oak has a stable supply of carbon through continuous photosynthesis. The maple draws upon reserves in the spring to build a new canopy. The buckeye draws upon reserves to build fruits in the fall as well as new canopy in...

Studies of atmospheric properties using IR spectroscopy techniques have been reported in the literature for nearly 100 years. This paper presents a brief historical review of the development of this area of science and discusses the common features of spectrographic instruments. Two state of the art instruments on opposite ends of the measurement spectrum are described. The first is a fast response iri situ sensor for the measurement of the exchange of CO2 between the atmosphere and the earth s surface. The second is a rocketborne field-widened spectrometer for upper atmosphere composition studies. The thesis is presented that most improvements in current measurement systems are due to painstakingly small performance enhancements of well understood system components. The source, optical and thermal control components that allow these sensors to expand the state of the art are detailed. Examples of their application to remote canopy photosynthesis measurement and upper atmosphere emission studies are presented. 

Chen, S.G., Shao, B.Y., Impens, I., and Ceulemos, R., Effects of plant canopy structure on light interception and photosynthesis, J. Quant. Spectrosc. Rad. Trans., 52, 115-123, 1994. 

Gimenez C., Connor, D.J., and Rueda, F., Canopy development, photosynthesis and radiation-use efficiency in sunflower in response to nitrogen, Field Crop Res., 38, 15-27, 1994. 

We next consider. /coz for specific values of C02 resistances and CO2 concentrations. We will use a CO2 mole fraction of 360 pmol mol-1 in the turbulent air around a leaf within a plant canopy, which corresponds to a CO2 concentration of (360)(0.0410), or 14.8 mmol CO2 m-3 at 20°C and a pressure of 0.1 MPa (see conversion factor in Table 8-2). Although we do not have reliable measurements of c, it may be about 8.0 mmol m-3 for a photorespiring plant at a saturating PPF. At 20°C, respiration plus photorespiration might be 30% as large as net photosynthesis. For purposes of calculation, we will let the gas phase resistance be 400 s m-1,... 

Hodanova, D. 1979. Sugar beet canopy photosynthesis as limited by leaf age and irradiance. Estimation by models. Photosynthetica 13 376-385. 

Hirose T. and Werger M. J. A. (1987) Maximizing daily canopy photosynthesis with respect to the leaf nitrogen allocation pattern in the canopy. Oecologia 72, 520-526. 

Pearcy R. W. (1990) Sunflecks and photosynthesis in plant canopies. Ann. Rev. Plant Physiol. 41, 421-453. 

Terashima I. and Hikosaka K. (1995) Comparative ecophysiol-ogy of leaf and canopy photosynthesis. Plant Cell Environ. 18, 1111-1128. 

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