David Da Silva - Profile on Academia.edu (original) (raw)

Papers by David Da Silva

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific ... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Proceedings of the 6th International Workshop on Functional-Structural Plant Models, FSPM 2010, September 12-17, 2010, University of California, Davis (USA)

Horticulture, Environment, and Biotechnology, 2016

The plastochron, defined as the time interval between the initiations of two successive leaves, c... more The plastochron, defined as the time interval between the initiations of two successive leaves, can also indicate the development of successive phytomers along a shoot. Previous work has shown that crop load impacts the plastochron in field-grown peach (Prunuspersica) trees, which led us to hypothesize that the plastochron of peach trees may be sensitive to the carbon status of the tree. To testthis hypothesis, a 38-day growth chamber study was conducted to determine if elevated CO2 (800 μmol•mol-1) speeds up the plastochron of young peach trees relative to their growth in ambient (400 μmol•mol-1) CO2. The leaf lamina lengths were measured every other day to generate leaf growth rate curves that were fitted against a classic Gompertz growth curve to estimate the time of the initiation of each leaf, which in turn, was used to estimate the plastochron. Additionally, in order to non-destructively gauge the effects of CO2 concentration on plant performance during the experiment, net leaf CO2 assimilation and stomatal conductance measurements were taken approximately half way through and at the end of the 38-day experiment. Doubling the ambient CO2 concentration had no effect on the plastochron, even though the leaf CO2 assimilation rates, leaf starch and total nonstructural carbohydrate concentrations were greater in trees grown in elevated CO2. In addition, there were no significant treatment differences in incremental shoot growth or the number of lateral syleptic shoots.

Storage of carbohydrate is essential for perennial plants survival, but its modeling is often uns... more Storage of carbohydrate is essential for perennial plants survival, but its modeling is often unsatisfactory. We studied the dynamics of reserve storage and mobilization in Peach trees and introduced a modeling approach that consider storage as an active sink rather than a passive buffer as frequently done in carbon-based models of tree growth.

Summary There is a current trend towards managing forests with multiple objectives, in particular... more Summary There is a current trend towards managing forests with multiple objectives, in particular to preserve or increase biodiversity and sustainab ility. There is renewed in terest in understorey vegetation as a way both to in crease the number of species a nd, indirectly, to favour fauna, including game, or improve soil quality. However, this stratum of herbaceous or shrubby species can also compete with young tree seedli ng and jeopardise tree regeneration. Hence a compromise has to be found among the different management objectives fo r the forest and in particular the understorey. Light is one of the main environmental factor s controlling ecological and biological processes in forests. For example, light quantity and light quality control the success of seed germination and the establishment and growth of tree seedlings in the understorey. Light also promotes the development of the floor vegetati on, the composition of which varies with site conditions in addition to light. M...

Warming winters due to climate change may critically affect temperate tree species. Insufficientl... more Warming winters due to climate change may critically affect temperate tree species. Insufficiently cold winters are thought to result in fewer viable flower buds and the subsequent development of fewer fruits or nuts, decreasing the yield of an orchard or fecundity of a species. The best existing approximation for a threshold of sufficient cold accumulation, the “chilling requirement” of a species or variety, has been quantified by manipulating or modeling the conditions that result in dormant bud breaking. However, the physiological processes that affect budbreak are not the same as those that determine yield. This study sought to test whether budbreak-based chilling thresholds can reasonably approximate the thresholds that affect yield, particularly regarding the potential impacts of climate change on temperate tree crop yields. County-wide yield records for almond (Prunus dulcis), pistachio (Pistacia vera), and walnut (Juglans regia) in the Central Valley of California were compa...

Sensitivity Analysis of Light Interception to Geometrical Traits of Apple Trees: An in Silico Study Based on Mapplet Model

IX International Symposium on Modelling in Fruit Research and Orchard Management, 2015

The efficiency of light interception is a driving factor for plant transpiration and photosynthes... more The efficiency of light interception is a driving factor for plant transpiration and photosynthesis, and contributes greatly to plant growth. For a fruit tree, the efficiency of light interception is also a key factor to improve yield quality. Such efficiency is highly dependent on the tree geometrical and topological organisation which may vary between genotypes, or as a result of agronomic practices such as pruning. The purpose of this study was to use a functional-structural plant model, in order to find out the major geometrical traits that influence the efficiency of light interception in apple trees. MAppleT, an architectural model of apple tree, and VPlants, a software library that includes functionalities to simulate light environment, provided the basis for this work. The STAR, namely the silhouette to total area ratio of leaves, was used to evaluate the light interception efficiency. The general methodology contained three steps: (1) manipulation of a set of geometrical parameters in MAppleT, such as those related to internode elongation, leaf area expansion, and branching angle; (2) integration of the resulting tree architecture within the simulated light environment for calculation of STAR values at the whole tree scale; (3) analysis of the influence of the variation of each geometrical trait on the variance of STAR outputs. As expected, leaf area manipulation had the highest impact on STAR values. Interactions between input parameters were also found, and are illustrated in the case of leaf area versus internode length. This suggests that optimal combination(s) of the corresponding traits could be found, setting a target for genetic improvement, as well as physiological studies on real apple trees.

Acta Horticulturae

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Rate of shoot development (phyllochron) is dependent of carbon availability, shoot type, and rank in peach trees

Trees

AoB PLANTS

The branch construction of trees is based on phytomers, repetitive subunits defined as node + lea... more The branch construction of trees is based on phytomers, repetitive subunits defined as node + leaf + axillary meristem + internode. The rate at which phytomers are added to a shoot is termed the phyllochron, which is determined by genetics, endogenous regulation and environmental conditions. The phyllochron is fundamental to understanding the growth of plants. Most phyllochron studies on woody species are of young plants under controlled conditions without consideration for different types of shoots that are present in mature trees. In this 2-year field study, we investigated seasonal patterns of phyllochron development on both proleptic and epicormic shoots of mature peach trees (Prunus persica) exposed to two irrigation treatments. One treatment was not irrigated until significant stress was detected via water potential by pressure bombing. In the second treatment trees were normally irrigated with ~5.84 cm of water each week to match evapotranspirational loss. Midday stem water potential readings were regularly collected to assess the level of water stress experienced by the trees. Measurements of individual leaves and their corresponding internodes were taken along tagged proleptic and epicormic shoots three times per week from the beginning to the end of two growing seasons. Leaf measurements were used to calculate the phyllochron. The phyllochron increased as the season progressed. This increase could not be explained by traditionally accepted effects of temperature or light. The more vigorous epicormic shoots added leaves significantly faster than proleptic shoots on trees in both water deficit and normally irrigated treatments. Additionally, epicormic shoots produced leaves with significantly greater leaf length and leaf area. Midday stem water potentials were more negative in trees in the water deficit treatments only after proleptic shoots stopped growing. The phyllochron did increase while leaf length and leaf area decreased on epicormic shoots of deficit irrigated trees in the 2010 growing season. The phyllochron of both shoot types gradually increased over the season, which was primarily due to an endogenous rank or shoot ageing effect. Differences between shoot types indicate that the phyllochron is variable among shoots on the same tree and is associated with shoot vigour. Water deficit increased the phyllochron and over all shoot growth rate.

Plant, cell & environment, Jan 18, 2017

Numerical plant models can predict the outcome of plant traits modifications resulting from genet... more Numerical plant models can predict the outcome of plant traits modifications resulting from genetic variations, on plant performance, by simulating physiological processes and their interaction with the environment. Optimization methods complement those models to design ideotypes, i.e. ideal values of a set of plant traits resulting in optimal adaptation for given combinations of environment and management, mainly through the maximization of a performance criteria (e.g. yield, light interception). As use of simulation models gains momentum in plant breeding, numerical experiments must be carefully engineered to provide accurate and attainable results, rooting them in biological reality. Here, we propose a multi-objective optimization formulation that includes a metric of performance, returned by the numerical model, and a metric of feasibility, accounting for correlations between traits based on field observations. We applied this approach to two contrasting models: a process-based ...

New Results - Analysis of structures resulting from meristem activity

Annals of botany, Aug 8, 2016

Plant growth depends on carbon availability and allocation among organs. QualiTree has been desig... more Plant growth depends on carbon availability and allocation among organs. QualiTree has been designed to simulate carbon allocation and partitioning in the peach tree (Prunus persica), whereas MappleT is dedicated to the simulation of apple tree (Malus × domestica) architecture. The objective of this study was to couple both models and adapt QualiTree to apple trees to simulate organ growth traits and their within-tree variability. MappleT was used to generate architectures corresponding to the 'Fuji' cultivar, accounting for the variability within and among individuals. These architectures were input into QualiTree to simulate shoot and fruit growth during a growth cycle. We modified QualiTree to account for the observed shoot polymorphism in apple trees, i.e. different classes (long, medium and short) that were characterized by different growth function parameters. Model outputs were compared with observed 3D tree geometries, considering shoot and final fruit size and growt...

& Context Light availability in forest understory is essential for many processes; it is, therefo... more & Context Light availability in forest understory is essential for many processes; it is, therefore, a valuable information regarding forest management. However, its estimation is often difficult and direct measurements are tedious. Models can be used to compute understory light, but they often require a lot of field data to accurately predict light distribution, particularly in the case of heterogeneous canopies. & Aims The influence of the precision level of crown description was studied with a model (MμSLIM) that can be used with both detailed and coarse parameterization with the aim of reducing field data requirements to a minimum. & Methods We analyzed the deterioration of the prediction quality of light distribution to the reduction of inputs by comparing simulations to transmitted light measurements in forests of increasing complexity in three different locations. & Results With a full set of parameters to describe the tree crown (i.e., crown extension in at least eight directions, crown height and length), the model accurately simulated the light distribution. Simplifying crown description by a geometric shape with a mean radius of crown extension led to deteriorated but acceptable light distributions. Allometric relationships used to calculate crown extension from trunk diameter at breast height seriously reduced light distribution accuracy.

Light sharing among different forest strata for sustainable management of vegetation and regeneration

There is a current trend towards managing forests with multiple objectives, in particular to pres... more There is a current trend towards managing forests with multiple objectives, in particular to preserve or increase biodiversity and sustainability. There is renewed interest in understorey vegetation as a way both to increase the number of species and, indirectly, to favour fauna, including game, or improve soil quality. However, this stratum of herbaceous or shrubby species can also compete with young tree seedling and jeopardise tree regeneration. Hence a compromise has to be found among the different management objectives for the forest and in particular the understorey. Light is one of the main environmental factors controlling ecological and biological processes in forests. For example, light quantity and light quality control the success of seed germination and the establishment and growth of tree seedlings in the understorey. Light also promotes the development of the floor vegetation, the composition of which varies with site conditions in addition to light. Modifying light a...

Interactions pour la lumière en forêt

Integration of leaf and internode growth functions in L-PEACH

2012 IEEE 4th International Symposium on Plant Growth Modeling, Simulation, Visualization and Applications, 2012

MAppleT is a functional-structural plant model that has been built for simulating architectural d... more MAppleT is a functional-structural plant model that has been built for simulating architectural development of apple trees. It has the capability of representing tree growth within a virtual space where the development of individual organs depends on geometrical traits. The purpose of this research is to investigate the influence of apple trees' architectural variability on their light interception efficiency. The STAR, i.e. the silhouette to total area ratio, of leaves, was chosen to evaluate the level of such efficiency. The strategy is to integrate MAppleT with the light interception model provided by the Fractalysis module of the VPlants software library. Target values of four major traits (internode length, leaf area, branching angle and top shoot diameter), are varied in range previously observed in a segregating population of apple hybrids. A sensitivity analysis based on polynomial and generalized additive models was performed for highlighting the most influential trait on light interception. The contribution of stochastic processes that control tree topology in MAppleT is also investigated in the sensitivity analysis. This study not only provides a time-and resource-saving alternative for data collection, but also sets a methodology for ideotype definition and further genetic improvement of apple trees.