Modelling Canopy Production. II. From Single-Leaf Photosynthesis Parameters to Daily Canopy Photosynthesis

1995 ◽  
Vol 22 (4) ◽  
pp. 603 ◽  
Author(s):  
PJ Sands
Keyword(s):  
Simple Algorithm ◽  
Light Response ◽  
Daily Maximum ◽  
Canopy Photosynthesis ◽  
Leaf Photosynthesis ◽  
Daily Production ◽  
Area Index ◽  
Single Leaf ◽  
Diurnal Temperature Variation ◽  
Analytical Expressions

This paper presents a simple algorithm for calculating daily canopy photosynthesis given parameters of the single-leaf light response, the canopy extinction coefficient, canopy leaf area index, daylength, daily solar irradiance and daily maximum and minimum temperatures. Analytical expressions are derived for total daily production by a canopy of leaves whose light response is either a rectangular hyperbola or a Blackman response. An expression which gives an excellent approximation to canopy photosynthesis for an arbitrary hyperbolic light response is then derived. These expressions assume photosynthetically active radiation (PAR) within the canopy follows Beer's law, light-saturated photosynthetic rate at any point in the canopy is proportional to the ratio of local PAR to full-sun PAR, diurnal variation of PAR is sinusoidal, and parameters of the single-leaf photosynthetic light response do not vary diurnally. It is shown how these expressions can be used to accommodate diurnal temperature variation of photosynthesis in a simple manner. The accuracy of the approximation to the basic integral of leaf photosynthesis over the canopy and over time is illustrated by applying the algorithm to compute the seasonal variation of daily canopy photosynthesis and comparing these data with corresponding values obtained by numerical integration.

Modelling Canopy Production. I. Optimal Distribution of Photosynthetic Resources

1995 ◽  
Vol 22 (4) ◽  
pp. 593 ◽  
Author(s):  
PJ Sands
Keyword(s):  
Photosynthetic Rate ◽  
Homogeneous Function ◽  
Nitrogen Concentration ◽  
Light Response ◽  
Leaf Nitrogen ◽  
Optimal Distribution ◽  
Canopy Photosynthesis ◽  
Area Index ◽  
Single Leaf ◽  
Canopy Nitrogen

On the basis of detailed numerical simulations, Field (1983. Oecologia 56, 341-347) stated that total canopy photosynthesis will be a maximum for a fixed total canopy leaf nitrogen provided the derivative δA/δN, where A is photosynthetic rate and N is leaf nitrogen concentration, has the same value throughout the canopy. This paper uses the calculus of variations to formally prove Field's assertion. It shows that if the single-leaf light response is a first-degree homogeneous function of both light-saturated photosynthetic rate Amax and intensity I of photosynthetically active radiation and if Amax is linearly related to N, then the optimal distribution of leaf nitrogen is linearly related to the decline in I with canopy depth, and Amax is proportional to this decline. The nature of photosynthetic gains due to optimisation of canopy nitrogen distribution is illustrated numerically for a simple model canopy. It is found that, for canopies with fixed mean leaf nitrogen, canopy photosynthesis is approximately proportional to canopy leaf area index (LAI), and the gain due to canopy optimisation compared with a uniform canopy is small for shallow canopies but pronounced for deep canopies. It is also found that, for canopies with fixed total leaf nitrogen, there is a canopy LAI which maximises canopy photosynthesis, and that this LAI and the corresponding canopy photosynthesis are approximately proportional to total canopy nitrogen.

Modelling Photosynthesis in Monocultures and Mixtures

1989 ◽  
Vol 16 (6) ◽  
pp. 501 ◽  
Author(s):  
IR Johnson ◽  
AJ Parsons ◽  
MM Ludlow
Keyword(s):  
Leaf Area ◽  
Good Representation ◽  
Canopy Photosynthesis ◽  
Leaf Photosynthesis ◽  
Important Special Case ◽  
Simple Modification ◽  
Single Leaf ◽  
Improved Performance ◽  
Analytical Expressions ◽  
Special Case

A comparison is made between two models of canopy photosynthesis for monocultures that differ in their treatment of the variation of the rate of single-leaf photosynthesis in response to the irradiance in which the leaves have grown. Both are shown to be deficient, and a simple modification to one that results in a much improved performance is presented. The theory uses the non-rectangular hyperbola for the rate of single-leaf photosynthesis and incorporates the Monsi-Saeki approach for the light-intercepting characteristics of the canopy. The model is then extended to describe the photosynthesis of mixed canopies, which requires knowledge of the relative position of each leaf-area component within the sward. Analytical expressions can be derived for the case where the leaf-area components are homogeneously distributed relative to each other through the depth of the canopy. This is shown to be a good representation of leaf-area distributions in continuously grazed temperate grass-clover swards as well as frequently cut tropical grass-legume swards, and so is an important special case.

Possibility of Increasing Yield Potential of Rice by Reducing Panicle Height in the Canopy. II. Canopy Photosynthesis and Yield of Isogenic Lines

1996 ◽  
Vol 23 (2) ◽  
pp. 161 ◽  
Author(s):  
TL Setter ◽  
EA Conocono ◽  
JA Egdane
Keyword(s):  
Field Experiments ◽  
Grain Filling ◽  
Canopy Height ◽  
Yield Potential ◽  
Isogenic Line ◽  
Canopy Photosynthesis ◽  
Area Index ◽  
Beneficial Effects ◽  
Isogenic Lines ◽  
Single Leaf

Reduced panicle height in a rice crop canopy may have beneficial effects of increasing yield potential through reduced shading of leaves leading to greater canopy photosynthesis. Effects of different panicle height in the canopy were evaluated in glasshouse and field experiments using isogenic lines with elongated upper internodes (EUI lines) from two cultivars. Isogenic lines of IR36 and IR50 with elongated upper internodes (IR36EUI and IR50EUI) had panicle heights at the top of the canopy of 96-100% of canopy height, while lines with low panicle heights had panicles which were 74 and 82% of canopy height respectively. Lines with low panicle height had about 10% more of the total leaf area index (LAI) above panicles and this resulted in up to 35% greater light interception by leaves above panicles relative to high panicle height plants. At 5 days before flowering IR36 and IR36EUI had equal canopy photosynthesis, while at flowering, lines had equal shoot nitrogen percentage and LAI. At maturity spikelets per mainstem were not significantly different. At 0, 7, 14 and 21 days after flowering (DAF), IR36, with low panicle height, had 10-30% greater canopy photosynthesis than IR36EUI; greater canopy photosynthesis was observed for IR50 relative to IR50EUI. These beneficial effects of low panicle height on canopy photosynthesis occurred even though the maximum single leaf photosynthesis and respiration rates were similar in both isogenic lines during grain filling. In the field and in a glasshouse experiment where plants were arranged into canopies, IR36, with low panicle heights had 15-40% greater yields than the isogenic line IR36EUI with high panicle heights; greater yields also occurred for IR50 than IR50EUI.

scholarly journals Canopy Photosynthetic Capacity and Light Response Parameters of Rubber Hevea brasiliensis with Reference to Exploitation

2013 ◽  
Vol 1 (1) ◽  
pp. 01-12 ◽  
Author(s):  
H Gunasekera ◽  
W De Costa ◽  
A Nugawela
Keyword(s):  
Leaf Area ◽  
Photosynthetic Rate ◽  
Photosynthetic Capacity ◽  
Light Response ◽  
Co2 Assimilation ◽  
Canopy Architecture ◽  
Canopy Photosynthesis ◽  
Canopy Layer ◽  
Area Index ◽  
Consistent Variation

The main objective of this study wasto investigate the relationship between canopy photosynthetic capacityand light response parametersof tapped and untapped trees of twoHeveabrasiliensis genotypes, i.e. RRISL 211 and RRIC 121. Moreover, attempts have been made to develop correlations between canopy photosynthesis and light response parameters Heveawith reference to exploitation. The canopy photosynthetic rates measured under optimal environmental conditions clearly showed clonal differences in CO2 assimilation rates. The photosynthetic capacities of leaves from all strata of RRISL 211 were greater than the corresponding strata values in RRIC 121. A greater canopy photosynthetic rate was observed in clone RRISL 211 despite its leaf area index being 2% lower than in RRIC 121. This could be because of the greater photosynthetic capacity of RRISL 211, as indicated by the greater Amax values.In each clone, Amax of the tapped trees was greater than the Amax of untapped trees, and this difference was greater in RRISL 211 than RRIC 121. Another reason for the greater canopy photosynthesis of clone RRISL 211 was the presence of a higher percentage of leaf area in the top canopy layer as compared to clone RRIC 121. Even though, the light saturation point, LSP (i.e. the light intensity at which photosynthetic rate reaches maximum), did not differ significantly between different canopy layers within a clone for both clones, RRIC 121 had greater LSP for corresponding layers than RRISL 211. Moreover, it was evident that, due to the more open canopy architecture of clone RRIC 121, LSP of its middle canopy layer was very close to LSP of the upper canopy layer.In both clones QE of all canopy layers did not show a consistent variation between tapped and untapped treatments The Rd rates of corresponding canopy layers were always slightly greater in RRISL 211 than in RRIC 121. In both clones there was a gradual reduction in Rd rates when moving from upper through middle to bottom layers of the canopy. However, detailed analysis of Rd rates in the different canopy layers between tapped and untapped treatments showed clonal differences. Nevertheless, in both clones Rd of all canopy layers did not show a consistent variation pattern between tapped and untapped treatments. The overall results of both clones clearly showed that tapped trees have a greater photosynthetic capacity as compared to untapped trees because tapping exerts a stimulatory effect on photosynthesis. This trend was more evident in clone RRISL 211.

Modelling Canopy Production. III. Canopy Light-Utilisation Efficiency and Its Sensitivity to Physiological and Environmental Variables

1996 ◽  
Vol 23 (1) ◽  
pp. 103 ◽  
Author(s):  
PJ Sands
Keyword(s):  
Meteorological Data ◽  
Canopy Structure ◽  
Light Response ◽  
Temperature Acclimation ◽  
Seasonal Temperature ◽  
Canopy Photosynthesis ◽  
Light Response Curve ◽  
Single Leaf ◽  
Theoretical Support ◽  
Utilisation Efficiency

A previously published model which predicts daily canopy photosynthesis from standard daily meteorological data and parameters of the single-leaf photosynthetic light-response curve is extended to predict annual canopy photosynthesis. The model is based on biologically plausible assumptions about canopy structure and assumes the single-leaf light response is a non-rectangular hyperbola of arbitrary shape. It uses simple algorithms for taking diurnal variation of temperature, and seasonal temperature acclimation of photosynthesis, into account. The model provides theoretical support for the observation that production by a canopy is proportional to irradiance intercepted or absorbed by the canopy. The model is used to explore the sensitivity of annual photosynthesis to parameters of the single-leaf light response. It is shown how the sensitivity of annual canopy photosynthesis to various factors can be determined from the sensitivity of parameters of the light response to the same factors. In particular, annual photosynthesis is shown to be sensitive to the effects of nutrition and temperature on light-saturated photosynthetic rate, and to seasonal temperature acclimation of photosynthesis. It is important that the variation with temperature, nutrition and season of parameters of the single-leaf light-response function be determined.

Sink-Source Relations in Cassava: Effects of Reciprocal Grafting on Yield and Leaf Photosynthesis

1994 ◽  
Vol 30 (3) ◽  
pp. 359-367 ◽  
Author(s):  
Didier Pellet ◽  
Mabrouk A. El-Sharkawy
Keyword(s):  
Leaf Gas Exchange ◽  
Sink Strength ◽  
Root Number ◽  
Leaf Photosynthesis ◽  
Gas Analyzer ◽  
Root Yield ◽  
Storage Roots ◽  
Area Index ◽  
Single Leaf ◽  
Infra Red

SUMMARYTwo contrasting clones of cassava (Manihot esculenta) were reciprocally grafted to test the hypothesis that the yield of cassava is limited by the number of storage roots. Effects of the root sink on leaf gas exchange were also tested under field conditions using a portable infra-red gas analyzer. Storage root number and root yield were affected by stock size and root yield was associated with the number of storage roots. The harvest index and sink-source ratio (root numberz/leaf area index) were correlated with root number. A feedback effect of root number on single-leaf photosynthesis was observed in one clone. It is concluded that the number of storage roots may be used as an indicator of sink strength.

Scaling leaf photosynthesis to canopy in a mixed deciduous forest. I. model description

1997 ◽  
Vol 62 ◽  
Author(s):  
R. Samson ◽  
S. Follens ◽  
R. Lemeur
Keyword(s):  
Temperature Dependence ◽  
Quercus Robur ◽  
Deciduous Forest ◽  
Growing Season ◽  
Model Description ◽  
Canopy Photosynthesis ◽  
Leaf Photosynthesis ◽  
Layer Model ◽  
Mixed Deciduous Forest ◽  
Leaf Level

A  multi-layer model (FORUG) was developed, to simulate the canopy  photosynthesis of a mixed deciduous forest during the growing season.  Measured photosynthesis parameters, for beech (Fagus  sylvatica), oak (Quercus  robur) and ash (Fraxinus  excelsior), were used as input to the model. This  information at the leaf level is then scaled up to the level of the canopy,  taking into account the radiation profiles (diffuse and direct PAR) in the  canopy, the vertical LAI distribution, the evolution of the LAI and the  photosynthesis parameters during the growing season, and the temperature  dependence of the latter parameters.

scholarly journals Interannual variability of net ecosystem carbon production and its climatic and biotic mechanism during 2005-2018 in a rain-fed maize ecosystem

2020 ◽  
Author(s):  
Hui Zhang ◽  
Tianhong Zhao ◽  
Sidan Lyu ◽  
Hang Wu ◽  
Yang Yang ◽  
...  
Keyword(s):  
Climate Changes ◽  
Daily Maximum ◽  
Spring Precipitation ◽  
Area Index ◽  
Carbon Production ◽  
Ecosystem Carbon ◽  
Spring Maize ◽  
Carbon Release ◽  
Northeast Of China ◽  
Beginning Date

AbstractThe interannual variation (IAV) of net ecosystem carbon production (NEP) plays an important role in understanding the mechanisms of the carbon cycle in the agriculture ecosystem. In this study, the IAV of NEP, which were expressed as annual values and anomalies, and its climatic and biotic controls mechanism, were investigated based on an eddy covariance dataset of rain-fed spring maize during 2005–2018 in the northeast of China. The annual NEP was 270±115 g C m−2yr −1. Annual values and anomalies of NEP were positively correlated with that of precipitation (PPT), gross ecosystem production (GEP) and daily maximum NEP (NEPmax). Annual anomalies of NEP were dominantly and positively controlled by the soil water content (SWC) through GEP and the soil temperature (Ts) through RE. In comparison, annual anomalies of NEP were dominantly and negatively controlled by summer VPD through the NEPmax, positively adjusted by spring precipitation and the effective accumulative temperature through the beginning date (BDOY) of the affecting carbon uptake period (CUP), and by autumn precipitation and leaf area index through the end date (EDOY) of the affecting CUP. Residues restrained the carbon release at the beginning of the year, and accelerated the carbon release at the end of the year. Our results hightlight that NEP might be more sensitive to the change of water condition (such as PPT, SWC and VPD) induced by the climate changes.

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