39 research outputs found
CoolBot Cold Room Monitoring Data Using Remote Sensor Designed by Kasetsart University
No full textCoolBot Cold Room Monitoring Data Using Remote Sensor Designed by Kasetsart Universit
CoolBot Cold Room Monitoring Data Using Remote Sensor Designed by Kasetsart University
No full textCoolBot Cold Room Monitoring Data Using Remote Sensor Designed by Kasetsart Universit
Waterlogging and restricted-below ground aeration on photosynthetic performance and root elongation rate of RRIM 600 and RRIT 251 rubber genotypes (Hevea brasiliensis Mull. Arg.)
No full textDue to extended inundation, waterlogging and restricted below-ground aeration cause inhibition in plant growth performance. This study examined two different rubber clones, RRIM 600 and RRIT 251, for waterlogging and restricted below ground aeration. To evaluate the plant performance under the stress conditions, net photosynthetic rate (PN), maximum quantum yield photosystem II (Fv/Fm) and root elongation rate were observed. RRIM 600 has a higher photosynthetic performance under normal conditions. However, the PN rate and Fv/Fm ratio trend showed that RRIM 600 seems to have difficulties recovering after exposure to restricted-below ground aeration. Although RRIT 251 had a lower tendency of PN rate under normal conditions, the PN rate and Fv/Fm ratio of this clone showed fast recovery. RRIT 251 also performed a higher trend of root elongation rate under both stress conditions than RRIM 600
Investigating rules of reserve mobilization and assimilate partitioning in young shaded beech through integrative modelling
No full textInternational audienc
Investigations sur le rôle de la mobilisation des réserves et le partage des assimilats chez le jeune hêtre à l'ombre à l'aide d'une approche de modélisation intégrée
No full textInternational audienceBeech (Fagus sylvatica L.) is a species of temperate broadleaved forests known to be very shade-tolerant. How does it manage to sustainably cope with very limited light resource? Processes must involve both C balance components (mainly photosynthesis vs. respiration) and efficient utilization/partitioning of the available C resource among the different sinks (mainly growth vs. reserve storage). We investigated them by combined experimental and integrated modelling approach
Investigating survival strategy of regenerating youg beech (Fagus sylvatica L.) under low light condition through integrative modeling
No full textInvestigating survival strategy of regenerating youg beech (Fagus sylvatica L.) under low light condition through integrative modeling. 2016 IEEE International Conference on Functional-Structural Plant Growth Modeling, Simulation, Visualization and Applications (FSPMA 2016
A photographic gap fraction method for estimating leaf area of isolated trees: assessment with 3D digitized plants
No full textA method for computing leaf area of isolated trees from perspective photographs was developed. The method is based on gap fraction inversion. Photographs are discretized into picture zones where gap fraction is computed from image processing. Canopy volume and leaf area density associated with each picture zone are computed from geometrical considerations and inversion of gap fraction equations. Total leaf area and the vertical profile of leaf area are computed from the product of associated volume and its density. The method has been implemented in software called Tree Analyser, written in C++. The method has been tested by comparison with direct estimation of leaf area of three-dimensional (3D) digitized trees of walnut, peach, mango, olive and rubber. Estimated leaf area was sensitive to picture discretization, individual leaf size and leaf inclination distribution. Optimal size of picture discretization was 17 times projected leaf size. Total leaf area was estimated by using a set of eight photographs taken around the tree in the main horizontal directions: deviation ranged from -11% in peach tree to +5% in rubber tree. The method allows fast and nondestructive monitoring of leaf area of individual tree canopies. The next version of the method will include the estimation of 3D leaf area distribution within the canopy
Investigating survival strategy of regenerating youg beech (Fagus sylvatica L.) under low light condition through integrative modeling
No full textInvestigating survival strategy of regenerating youg beech (Fagus sylvatica L.) under low light condition through integrative modeling. 2016 IEEE International Conference on Functional-Structural Plant Growth Modeling, Simulation, Visualization and Applications (FSPMA 2016
Investigations sur la stratégie de survie des jeunes hêtres (Fagus sylvatica L.) sous faibles conditions de lumière avec une approche de modélisation intégrative
No full textInternational audienceBeech (Fagus sylvatica L.) is a shade tolerant species of broadleaved temperate forests from the northern hemisphere. However, how it manages to survive low irradiance conditions is debated. This must involve both carbon balance components (mainly photosynthesis vs. respiration) and efficient utilization / partitioning of the available C resource among the different sinks (mainly growth vs. reserve storage). This survival strategy was investigated through a combined experimental and modelling approach. Four-year-old beech seedlings growing in the understorey of natural Scots pine stands were 3D-digitized in summer for architecture, including woody parts (growth units) and leaves. Then seedlings were harvested in autumn and winter to quantify biomass and carbohydrate reserve contents of each organ, both above and below ground. Roots were separated into 3 classes: taproot, main lateral roots and fine roots, and shoot segments according to their age. These data were used to construct 3D-digital mockups of the young trees and to parameterize and initialize the carbon-based functional-structural model PIAF-1. Additional beech-specific parameters relevant to phenology and gas exchange rates were derived from similar experiments or literature. Meteorological data (daily radiation and temperature) were generated for each tree based on recorded weather data. Transmitted solar irradiance above each seedling was calculated from hemispherical photographs and the global radiation above the stand. The first results suggest that under the most restrictive light conditions, the reserve store was just sufficient for the spring outgrowth. The major factor allowing the seedling to pass the short but critical near-zero-reserve phase appeared to be the leaf growth strategy, with surface area expanding prior to structural hardening. The reserve mobilization strategy showed only as a second factor, with the mobilization rate likely not limiting in contrast to the total reserve store
Simulation of growth and development of beech seedlings growing in different light environments using PIAF-1.
No full textThe European beech (Fagus silvatica L.) is a late-successional shade tolerant species. It is often cultivated and managed with the shelterwood system in Europe, meaning that its natural regeneration takes place in shade. Under low light conditions, seedling size must stay below a threshold where carbon gain and carbon balance remain positive. This is not so easy to determine experimentally. Therefore, a simulation approach using the carbon-based functional-structural model PIAF-1 (Lacointe and Donès, 2007) was used to investigate the relationship between carbon balance and growth of young beech trees under low light availability. Two-year-old beech seedlings were planted in March 2007 in the understorey of natural Scots pine stands in Fontfreyde, Chaîne des puys, France. In summer 2009, nine beech seedlings were sampled under light availability ranging from 7 to 28% of incident light. To acquire their architecture, aboveground parts of each tree were 3D-digitized, including woody parts (growth units) and leaves using PiafDigit (Donès et al., 2006). Then seedlings were harvested in autumn and winter to quantify biomass and starch and sucrose contents of each organ, above and below ground. Roots were separated into 3 classes: taproot, main lateral roots and fine roots. Each part was scanned and the length and diameter of roots were assessed using WinRhizo (Regent Instruments Inc., Canada). These data were used to parameterize and initialize PIAF-1. The digitized aboveground parts were converted from growth units to cylindrical segments bearing leaves in their true place and orientation. Belowground parts were reconstructed based on diameter and length of each root class. Meteorological data (hourly light and temperature) were generated for each tree based on recorded weather data. Transmitted solar irradiance above each seedling was calculated from hemispherical photographs and the global radiation above the stand. Each seedling was visualized on a PIAF-1 3D visualization interface. The quality of the reconstructed seedlings was assessed by comparing the graphical outputs from PIAF-1 with those from VegeSTAR (Adam et al., 2002) using Tree Analyser (Phattaralerphong et al., 2005) to compute synthetic geometrical properties such as total leaf area or density. Potential growth, amount of storage, and reserve capacity of stem, leaf and root are still being analyzed. Results of simulations will be reported and discussed
