Using a Full Spectral Raytracer for Calculating Light Microclimate in Functional-Structural Plant Modelling

Raytracers that allow the spatially explicit calculation of the fate of light beams in a 3D scene allow the consideration of shading, reected and transmitted light in functional-structural plant models (FSPM). However, the spectrum of visible light also has an e ect on cellular and growth processes. This recently created the interest to extend this modelling paradigm allowing the representation of detailed spectra instead of monochromatic or white light and to extend existing FSPM platforms accordingly. In this study a raytracer is presented which supports the full spectrum of light and which can be used to compute spectra from arbitrary light sources and their transformation at the organ level by absorption,reection and transmission in a virtual canopy. The raytracer was implemented as an extension of the FSPM platform GroIMP

FSPM-P: towards a general functional-structural plant model for robust and comprehensive model development

In the last decade, functional-structural plant modelling (FSPM) has become a more widely accepted paradigm in crop and tree production, as 3D models for the most important crops have been proposed. Given the wider portfolio of available models, it is now appropriate to enter the next level in FSPM development, by introducing more efficient methods for model development. This includes the consideration of model reuse (by modularisation), combination and comparison, and the enhancement of existing models. To facilitate this process, standards for design and communication need to be defined and established. We present a first step towards an efficient and general, i.e., not speciesspecific FSPM, presently restricted to annual or bi-annual plants, but with the potential for extension and further generalization. Model structure is hierarchical and object-oriented, with plant organs being the base-level objects and plant individual and canopy the higher-level objects. Modules for the majority of physiological processes are incorporated, more than in other platforms that have a similar aim (e.g., photosynthesis, organ formation and growth). Simulation runs with several general parameter sets adopted from the literature show that the present prototypewas able to reproduce a plausible output range for different crops (rapeseed, barley, etc.) in terms of both the dynamics and final values (at harvest time) of model state variables such as assimilate production, organ biomass, leaf area and architecture

QTLs for salt tolerance in three different barley mapping populations 2006

Soil salinity is one of the crucial factors limiting crop production. Progression of salinisation of agriculturally arable land is mainly connected with mismanagement of water in irrigation systems, in particular under arid and semiarid climate conditions and global changes of water flow in the landscape. Selection of salt tolerant genotypes is necessary to ensure yield and to reclaim salt affected soils. The development of molecular marker(s) could facilitate the selection process. Phenotyping of mapping populations under salt stress conditions and calculation of QTLs are suitable instruments to detect markers that are responsible for tolerance/sensitivity. However, a quantitative inherited trait like salt tolerance requires a range of adaptations, with a whole host of genes interacting with each other to produce the visible phenotype

Towards a Multi-Scaled Functional-Structural Model of Apple, Linking Ecophysiology at the Fruit and Branch Scales

A multitude of data on eco-physiological processes in apple (Malus x domestica) is available, concerning various aspects of fruit growth and development, fruit quality, or leaf photosynthesis. However, despite the wealth of data and studies many processes leading to (inter-annual and intra-arboreal) heterogeneity in quantity of fruit production as well as fruit quality are still only poorly understood at the branch level Current Functional-Structural Plant Models of apple have targeted canopy architecture, i.e. development of vegetative structures. Here we will present a concept to apply the FSPM paradigm to the simulation of assimilation (source), transport and consumption (sink) of carbon in the context of a static structure representing the limb (fruit-bearing branch)

Simulating Superior Genotypes for Plant Height based on QTLs: Towards Virtual Breeding of Rice

Crop plant researchers and agronomists have in the recent past increasingly turned to crop modeling as a promising tool for the integration and exploration of experimental data from breeding and agronomy. Set up suitably, crop modeling can then also be used to predict performance of future high-yielding cultivars, e. g. of rice, which is one of the major food crops worldwide. Questions such as "Which combination of alleles is likely to have the strongest influence on the development of the individual phenotype?" or "In which way is QTL action modified by a particular environment?" can be tackled with the help of a crop modeling approach. As a further extension of a previously established Functional-Structural Plant model (FSPM) of rice we present here simulated "virtual" reproduction of individuals using QTL information, which can contribute to providing answers to these difficult questions. In this study, we briefly describe the way QTL information has been integrated into the rice model, and sketch the algorithmic implementation of processes leading to the creation of filial genotypes from parental genotypes via simulated sexual reproduction. The phenotype value, which in this case was plant height, was determined with the rules that specify the genetic processes operating on genotypes as intrinsic properties of each individual. The mapping results from the simulated population were compared with the input values for the parental lines. It is shown that the rice model faithfully reflected the genetic properties from the parental lines with low bias, which suggests a reasonable way to integrate QTLs into the plant eco-physiological model with the predictive properties. It could in the future be used as a supporting tool in breeding practice

Towards a functional-structural plant model of cut-rose: simulation of light environment, light absorption, photosynthesis and interference with the plant structure

Background and Aims The production system of cut-rose (Rosa × hybrida) involves a complex combination of plant material, management practice and environment. Plant structure is determined by bud break and shoot development while having an effect on local light climate. The aim of the present study is to cover selected aspects of the cut-rose system using functional–structural plant modelling (FSPM), in order to better understand processes contributing to produce quality and quantity. Methods The model describes the production system in three dimensions, including a virtual greenhouse environment with the crop, light sources (diffuse and direct sun light and lamps) and photosynthetically active radiation (PAR) sensors. The crop model is designed as a multiscaled FSPM with plant organs (axillary buds, leaves, internodes, flowers) as basic units, and local light interception and photosynthesis within each leaf. A Monte-Carlo light model was used to compute the local light climate for leaf photosynthesis, the latter described using a biochemical rate model. Key Results The model was able to reproduce PAR measurements taken at different canopy positions, different times of the day and different light regimes. Simulated incident and absorbed PAR as well as net assimilation rate in upright and bent shoots showed characteristic spatial and diurnal dynamics for different common cultivation scenarios. Conclusions The model of cut-rose presented allowed the creation of a range of initial structures thanks to interactive rules for pruning, cutting and bending. These static structures can be regarded as departure points for the dynamic simulation of production of flower canes. Furthermore, the model was able to predict local (per leaf) light absorption and photosynthesis. It can be used to investigate the physiology of ornamental plants, and provide support for the decisions of growers and consultants.                    

Linking integrative plant physiology with agronomy to sustain future plant production

Sustainable production of high-quality food is one of today's major challenges of agriculture. To achieve this goal, a better understanding of plant physiological processes and a more integrated approach with respect to current agronomical practices are needed. In this review, various examples of cooperation between integrative plant physiology and agronomy are discussed, and this demonstrates the complexity of these interrelations. The examples are meant to stimulate discussions on how both research areas can deliver solutions to avoid looming food crises due to population growth and climate change. In the last decades, unprecedented progress has been made in the understanding of how plants grow and develop in a variety of environments and in response to biotic stresses, but appropriate management and interpretation of the resulting complex datasets remains challenging. After providing an historical overview of integrative plant physiology, we discuss possible avenues of integration, involving advances in integrative plant physiology, to sustain plant production in the current post-omics era. Finally, recommendations are provided on how to practice the transdisciplinary mindset required, emphasising a broader approach to sustainable production of high-quality food in the future, whereby all those who are involved are made partners in knowledge generation processes through transdisciplinary cooperation. © 2020 Elsevier B.V

Oecologie en plantensociologische positie van Cirsium dissectum (L.) Hill in Oostfriesland

Verspreiding van de distel de Spaanse ruite

Modelling temporal variation of parameters used in two photosynthesis models: influence of fruit load and girdling on leaf photosynthesis in fruit-bearing branches of apple

Background and Aims: Several studies have found seasonal and temporal variability in leaf photosynthesis parameters in different crops. This variability depends upon the environment, the developmental stage of the plant and the presence or absence of sinks. Girdling involves the removal of the bark and phloem down to the youngest xylem all around the stem and prevents export of photoassimilates out of the stem. The load of developing fruits has often been reported to influence the individual net leaf photosynthesis rate (Pn) in tree crops. In this study, we chose (1) to model the key parameters of photosynthesis models of leaves (Pgmax, Rd, α and θ) as a function of time and using these two means (girdling and low fruit load) to alter the source-sink balance and (2) to compare three models: the rectangular and non-rectangular hyperbola model by Thornley, as well as the non-rectangular hyperbola model by Marshall and Biscoe. Methods: Six-year-old fruit-bearing branches of 10-year-old apple trees were used to study and model the seasonal variation of photosynthetic parameters in leaves of vegetative shoots, as a function of global fruit load (at the branch level), with or without girdling, during the growing season of 2015. Three treatments were applied: control, low load (LL) or low load + girdling (LLG). For each fruit-bearing branch, light-response curves of Pn for two leaves of vegetative shoots were measured at two different positions, proximal and distal. Key Results: The model of Marshall and Biscoe was the most accurate for the simulation of Pn in fruit-bearing branches of apple trees with time (season) and the three treatments applied. Conclusion: The present study proposed a way to model the photosynthesis rate by temporal and environmental variables only. A proper validation of this model will be necessary to extend its utilization and appreciate its predictive capacity fully