Remote sensing of leaf nutrition and its incorporation for biochemical and environmental modeling of crop photosynthesis and evapotranspiration

  • Boegh, Eva, (Projectkoordinator)
  • Jensen, Niels H. (Projektdeltager)
  • Thomsen, Anton (Projektdeltager)
  • Schelde, Kirsten (Projektdeltager)
  • Hansen, Søren (Projektdeltager)
  • Abrahamsen, Per (Projektdeltager)
  • Gjetterman, Birgitte (Projektdeltager)
  • Søgaard, Henrik (Projektdeltager)

Projekter: ProjektForskning

Beskrivelse

Photosynthesis and stomatal movements are physiological processes that occur within leaves but whose influences on CO2, water vapour and sensible heat fluxes extends to canopy, regional and global scales. Currently, agricultural nutritional policies and a warmer climate are changing conditions for photosynthesis and crop growth in Denmark. The implementation of still more stringent agricultural policies during the last 15-20 years has led to sub-optimal nitrogen quotas corresponding to 90 % of the economically optimal for farmers. Apart from its direct impact on photosynthesis and crop growth, nitrogen stress increases leaf temperature and it can have a substantial effect on the evapopotranspiration that may extend to affect water balance and the climate system at larger scales. Amongst the changes related to restricted agricultural nutrient availability, a warmer climate is approaching to which farmers in Denmark are adapting by introducing more maize crops in their fields. In future, it is also expected that global warming will reduce summertime precipitation to 80 % of its present level in Denmark.
 
In order to study the impact of land use and environmental changes, realistic photosynthesis and stomatal conductance models representing the different biochemical and physiological properties of C3 and C4 leaves must be used. For instance, maize is a C4 crop which is more tolerant to high temperatures and nitrogen/water stresses that are grain (C3) crops. C4 crops also have lower stomatal conductances and their introduction could alter regional hydrology and surface energy balance.
 
The objective of the project is to exploit the feasibilities of new measurements technique and high resolution Earth Observation (EO) data to measure and quantify the impact of temporal and spatial variations in leaf are index and leaf nitrogen nutrition levels on photosynthesis and evapotranspiration and to assess its role for the surface energy - and water balance.
Spectral/laser crop sensors developed at DIAS and high spatial resolution EO data are used to define methods for mapping crop status in terms of leaf area index (LAI), chlorophyll contents and leaf nitrogen contents.
Field measurements of leaf gas fluxes and soil moisture are used to define relationships between leaf nitrogen and key leaf photosynthetic parameters.
Leaf nutrition information is integrated in a biochemical photosynthesis-stomatal conductance model and incorporated in the Daisy model (http://www.dina.kvl.dk/~daisy).
Spatial variations in LAI and leaf nitrogen are mapped and used in DaisyGIS (http://www.dhisoftware.com/mikeshe/Add-on_Modules/DaisyGIS/) for modeling the effect of leaf nutrition/LAI, agricultural land use and climate interaction on photosynthesis, evapotranspiration and water balance within a Danish agricultural landscape
StatusAfsluttet
Effektiv start/slut dato01/01/200531/12/2007

Finansiering

  • National Agricultural Research Council

Emneord

  • remote sensing
  • kvælstof
  • agro-hydrologisk modellering