Functional control of nitrogen distribution in heterogeneous plant canopies

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Light energy is the driving force of photosynthesis, and nitrogen is often a limiting factor for the construction of the photosynthetic apparatus. Plants continuously adjust their leaf traits to the variable intra-canopy light conditions in order to utilize the light energy efficiently for photosynthesis. These adaption mechanisms can be observed in the modifications of nitrogen partitioning between photosynthetic functions, leaf nitrogen concentration, and the ratio between leaf area and leaf mass. It has been predicted by modelling approaches that when the gradients of nitrogen and light intensity are coordinated in the canopy, whole plant photosynthesis reaches its maximum. However, these models do not take into account spatial (horizontal) heterogeneity in canopy structure and light distribution, which is the reality in many high value crops. This project aims to better understand canopy nitrogen distribution and photosynthetic nitrogen partitioning in heterogeneous plant canopies, using an explicit representation of (heterogeneous) canopy structure by a functional-structual plant model (FSPM). The knowledge gained should provide the basis for quantification of the influence of light environment, nitrogen availability and genotypic variation on nitrogen partitioning and nitrogen distribution. The improved quantitative understanding is intended to be applied for a science-based improvement crop management measures like nitrogen fertilization, supplemental lighting, planting arrangement or training system, and to assist in the choice of the cultivars according to the expected growth light conditions.