scholarly journals Isoprene Emission from Velvet Bean Leaves (Interactions among Nitrogen Availability, Growth Photon Flux Density, and Leaf Development)

1994 ◽  
Vol 105 (1) ◽  
pp. 279-285 ◽  
Author(s):  
P. C. Harley ◽  
M. E. Litvak ◽  
T. D. Sharkey ◽  
R. K. Monson
Keyword(s):  
Flux Density ◽  
Leaf Development ◽  
Nitrogen Availability ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Velvet Bean ◽  
Isoprene Emission ◽  
Bean Leaves

Intra-Leaf Gradient of Assimilation Rate and Optimal Allocation of Canopy Nitrogen: a Model on the Implications of the Use of Homogeneous Assimilation Functions.

1995 ◽  
Vol 22 (3) ◽  
pp. 425 ◽  
Author(s):  
FW Badeck
Keyword(s):  
Flux Density ◽  
Nitrogen Availability ◽  
Optimal Allocation ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Allocation Pattern ◽  
Experimental Findings

A model on the allocation of nitrogen available for the construction of photosynthetic apparatus in leaves in different morphological positions is presented. The allocation pattern is calculated under the assumption that nitrogen distribution is optimised in order to maximise daily whole-plant assimilation. The solution is fairly sensitive to the assimilation function applied. It is shown that assimilation functions homogeneous in irradiance and nitrogen imply assimilation gradients and light-saturation characteristics of the whole canopy which contradict experimental findings. An equation for the calculation of electron transport rates as a function of the intra-leaf gradient of the photosynthetic photon flux density is presented. This inhomogeneous assimilation function leads to substantially different predictions of nitrogen allocation which reproduce a wider array of observed allocation patterns. The results presented in this paper support the thesis that the intra-leaf gradient of photosynthetic photon flux density and self-shading of the thylakoids need to be considered if the assimilation flux is to be modelled as a function of light as well as nitrogen availability on a mechanistic basis.

Transient Depression of Photosynthesis in Bean Leaves During Rapid Water Loss

1993 ◽  
Vol 20 (1) ◽  
pp. 45 ◽  
Author(s):  
H Modau ◽  
SC Wong ◽  
CB Osmond
Keyword(s):  
Partial Pressure ◽  
Flux Density ◽  
Water Loss ◽  
Loss Rate ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Co2 Uptake ◽  
Co2 Partial Pressure ◽  
Water Loss Rate ◽  
Bean Leaves

The response of the photosynthetic capacity of mesophyll to a rapid loss of water from the leaf was evaluated by measuring transpiration, net CO2 uptake and temperature in dwarf bean leaves exposed to saturating CO2 partial pressures in a leaf chamber before and after cutting the petiole in air. Some plants were pre-exposed to low or high photon flux density, or to water deficit before measurements. During 3-5 min after cutting, when the turgorpassive opening of the stomata accelerated the water loss from the leaf, the rate of CO2 uptake was depressed; the depression was more pronounced in young leaves, under higher CO2 partial pressure, and in leaves pre-exposed to low photon flux density or to slight water deficit. During subsequent closure of the stomata, the CO2 uptake rate accelerated, although the leaf water content and the internal CO2 partial pressure declined. The depression in CO2 uptake was poorly correlated with the water loss rate after cutting, but it was positively correlated with the increase in water loss rate relative to the transpiration rate before the cutting. It is speculated that sharp perturbation in leaf water regime may induce a transient leakage of cellular membranes and redistribution of metabolites between cell compartments, resulting in a depression of photosynthesis. Subsequent restoration of the concentrations of metabolites in compartments tends to restore the rate of photosynthesis, which then declines due to substantial stomatal closure.

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