The effect of elevated CO₂ concentrations on the levels of secondary metabolites was investigated in tobacco plants grown under two nitrogen supply (5 and 8 mm NH₄NO₃) and CO₂ conditions (350 and 1000 p.p.m.) each. High CO₂ resulted in a dramatic increase of phenylpropanoids in the leaves, including the major carbon‐rich compound chlorogenic acid (CGA) and the coumarins scopolin and scopoletin at both nitrogen fertilizations. This was accompanied by increased PAL activity in leaves and roots, which was even higher at the lower nitrogen supply. Hardly any change was observed for the structural phenolic polymer lignin and the sesquiterpenoid capsidiol. In contrast, elevated CO₂ led to clearly decreased levels of the main nitrogen‐rich constituent nicotine at the lower N‐supply (5 mm NH₄NO₃) but not when plants were grown at the higher N‐supply (8 mm NH₄NO₃). Inoculation experiments with potato virus Y (PVY) were used to evaluate possible ecological consequences of elevated CO₂. The titre of viral coat‐protein was markedly reduced in leaves under these conditions at both nitrogen levels. Since PR‐gene expression and free salicylic acid (SA) levels remained unchanged at elevated CO₂, we suggest that the accumulation of phenylpropanoids, for example, the major compound CGA and the coumarins scopolin and scopoletin may result in an earlier confinement of the virus at high CO₂. Based on our results two final conclusions emerge. First, elevated CO₂ leads to a shift in secondary metabolite composition that is dependent on the availability of nitrogen. Second, changes in the pool of secondary metabolites have important consequences for plant–pathogen interactions as shown for PVY as a test organism.

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. 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. 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. 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.

In the present paper, we based a search for candidates underlying different levels of salinity tolerance during germination in the Oregon Wolfe Barley mapping population (DOM × REC) by proteomic profiling of the mature grain of lines showing differing levels of salinity tolerance. By contrasting the parents DOM and REC, displaying divergent stress responses, and two tolerant and two sensitive segregants, six protein spots were identified that showed a differential abundance between the tolerant and the sensitive lines. The tolerant lines expressed a higher level of 6‐phosphogluconate dehydrogenase and glucose/ribitol dehydrogenase (Glc/RibDH). Both proteins were heterologously over‐expressed in an osmo‐sensitive yeast strain and over‐expression of Glc/RibDH resulted in an enhanced ability of yeast transformants to grow on salt containing media. A quantitative trait locus (QTL) analysis of the population germinating at different salt concentrations led to the identification of two chromosome regions on 5H and one on 7H associated with salt stress response. A dense barley transcript map was employed to map the genomic region of all identified proteins. Two of these, heat‐shock protein 70 and Glc/RibDH, co‐localized with the identified QTL on chromosome 5H. The putative functional role of the candidates is discussed.

Although quantitative trait loci (QTL) analysis of yield-related traits for rice has developed rapidly, crop models using genotype information have been proposed only relatively recently. As a first step towards a generic genotype–phenotype model, we present here a three-dimensional functional–structural plant model (FSPM) of rice, in which some model parameters are controlled by functions describing the effect of main-effect and epistatic QTLs. The model simulates the growth and development of rice based on selected ecophysiological processes, such as photosynthesis (source process) and organ formation, growth and extension (sink processes). It was devised using GroIMP, an interactive modelling platform based on the Relational Growth Grammar formalism (RGG). RGG rules describe the course of organ initiation and extension resulting in final morphology. The link between the phenotype (as represented by the simulated rice plant) and the QTL genotype was implemented via a data interface between the rice FSPM and the QTLNetwork software, which computes predictions of QTLs from map data and measured trait data. Using plant height and grain yield, it is shown how QTL information for a given trait can be used in an FSPM, computing and visualizing the phenotypes of different lines of a mapping population. Furthermore, we demonstrate how modification of a particular trait feeds back on the entire plant phenotype via the physiological processes considered. We linked a rice FSPM to a quantitative genetic model, thereby employing QTL information to refine model parameters and visualizing the dynamics of development of the entire phenotype as a result of ecophysiological processes, including the trait(s) for which genetic information is available. Possibilities for further extension of the model, for example for the purposes of ideotype breeding, are discussed.

Reduction of energy use for assimilation lighting is one of the most urgent goals of current greenhouse horticulture in the Netherlands. In recent years numerous lighting systems have been tested in greenhouses, yet their efficiency has been very difficult to measure in practice. This simulation study evaluated a number of lighting strategies using a 3D light model for natural and artificial light in combination with a 3D model of tomato. The modeling platform GroIMP was used for the simulation study. The crop was represented by 3D virtual plants of tomato with fixed architecture. Detailed data on greenhouse architecture and lamp emission patterns of different light sources were incorporated in the model. A number of illumination strategies were modeled with the calibrated model. Results were compared to the standard configuration. Moreover, adaptation of leaf angles was incorporated for testing their effect on light use efficiency. A Farquhar photosynthesis model was used to translate the absorbed light for each leaf into a produced amount of carbohydrates. The carbohydrates produced by the crop per unit emitted light from sun or HPS lamps was the highest for horizontal leaf angles or slightly downward pointing leaves, and was less for more upward leaf orientations. The simulated leaf angles did not affect light absorption from inter-lighting LED modules, but the scenario with LEDs shining slightly upward (20°) increased light absorption and light use efficiency relative to default horizontal beaming LEDs. Furthermore, the model showed that leaf orientation more perpendicular to the string of LEDs increased LED light interception.The combination of a ray tracer and a 3D crop model could compute optimal lighting of leaves by quantification of light fluxes and illustration by rendered lighting patterns. Results indicate that illumination efficiency increases when the lamp light is directed at most to leaves that have a high photosynthetic potential.