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Virtual Crop Modelling for Technology Impact Assessment -Lessons from a Potato Crop Growth Model

Authors:
  • Federal Ministry of Food and Agriculture, Berlin, Germany

Abstract

Efforts are under way in the agricultural research for development community to employ crop growth simulation models for the ex-ante assessment of the impacts of agricultural technologies, in particular improved crop varieties. The approach, dubbed “virtual crop modelling”, consists in the manipulation of genetic coefficients of the cultivars contained in crop growth models to simulate productivity effects of genetic improvements brought about by future breeding efforts and assesses the impacts of these improvements under field conditions. However, the suitability of the models for this purpose is not yet proven. In an effort to explore the suitability of crop growth models for virtual crop modelling, the DSSAT-SUBSTOR potato growth model, a model which simulates potato growth as a function of abiotic, but not of biotic factors, is used to carry out a sensitivity analysis of changes in genetic coefficients of a modern tropical potato cultivar. Yields are simulated across a wide range of genetic coefficients of the crop model at sites located in four contrasting tropical, subtropical and temperate environments. Simulation results show that the model responds to parameter changes as expected and that it gives meaningful results in all tested environments. Site characteristics appear to play an important role for potential simulated yield levels and for the responses of the model to changes in genetic coefficients. However, there is substantial unexploited potential for productivity growth from improved management practices. This potential appears to be greater than the benefits from genetic improvements that appear likely today. The analysis shows that, by helping to identify yield constraints for different environments, crop modelling can make substantial contributions to ex-ante impact assessment of agricultural technologies. Virtual crop modelling, however, is only a viable option if crop growth is actually constrained by those genetic factors which are represented by adjustable genetic coefficients of a given crop model. Furthermore, the scope of many crop models is limited to abiotic yield-limiting factors and an extension towards biotic factors, e.g. a linkage with disease models, might be necessary for some environments.
Tropentag, September 17-19, 2013, Stuttgart-Hohenheim
“Agricultural development within the rural-urban continuum”
Virtual Crop Modelling for Technology Impact Assessment -
Lessons from a Potato Crop Growth Model
Ulrich Kleinwechter1, Senthold Asseng2, Manuel Gastelo3, Joe Ritchie2, Gerald C.
Nelson4
1International Potato Center (CIP), Social and Health Sciences Global Program, Peru
2University of Florida, Agricultural & Biological Engineering Department, United States
3International Potato Center (CIP), Genetics and Crop Improvement Global Program, Peru
4International Food Policy Research Institute (IFPRI), Environment and Production Technology Division,
United States
Abstract
Efforts are under way in the agricultural research for development community to employ
crop growth simulation models for the ex-ante assessment of the impacts of agricultural
technologies, in particular improved crop varieties. The approach, dubbed “virtual crop
modelling”, consists in the manipulation of genetic coefficients of the cultivars contained
in crop growth models to simulate productivity effects of genetic improvements brought
about by future breeding efforts and assesses the impacts of these improvements under
field conditions. However, the suitability of the models for this purpose is not yet proven.
In an effort to explore the suitability of crop growth models for virtual crop modelling,
the DSSAT-SUBSTOR potato growth model, a model which simulates potato growth as
a function of abiotic, but not of biotic factors, is used to carry out a sensitivity analysis
of changes in genetic coefficients of a modern tropical potato cultivar. Yields are simula-
ted across a wide range of genetic coefficients of the crop model at sites located in four
contrasting tropical, subtropical and temperate environments.
Simulation results show that the model responds to parameter changes as expected and
that it gives meaningful results in all tested environments. Site characteristics appear to
play an important role for potential simulated yield levels and for the responses of the model
to changes in genetic coefficients. However, there is substantial unexploited potential for
productivity growth from improved management practices. This potential appears to be
greater than the benefits from genetic improvements that appear likely today.
The analysis shows that, by helping to identify yield constraints for different environ-
ments, crop modelling can make substantial contributions to ex-ante impact assessment of
agricultural technologies. Virtual crop modelling, however, is only a viable option if crop
growth is actually constrained by those genetic factors which are represented by adjustable
genetic coefficients of a given crop model. Furthermore, the scope of many crop models
is limited to abiotic yield-limiting factors and an extension towards biotic factors, e.g. a
linkage with disease models, might be necessary for some environments.
Keywords: Crop improvement, crop modelling, DSSAT, ex-ante impact assessment, potatoes, SUB-
STOR
Contact Address: Ulrich Kleinwechter, International Potato Center (CIP), Social and Health Sciences Global Pro-
gram, Apartado 1558, 12 Lima, Peru, e-mail: u.kleinwechter@cgiar.org
Article
Potato has been recognized as a crop of importance in developing countries for ensuring human nutrition and food security. The dwindling natural resources, low fertility of soils, the incidence of pests and diseases, climate change and lack of strategic planning pose major constraints for potato production in these countries. Crop models are efficient tools for assisting research and development efforts towards achieving maximum production potential in these areas as it predicts the phenology and yield of crop taking into consideration the factors affecting growth and development. A well-validated model can be used for quantification of adaptation domains, optimization and efficient utilization of resources, forecasting of pest and diseases, mitigating climate changes, yield gap analysis, a pre-harvest judgment of production and accordingly market surveillance and formulation of monitory policies. The multifaceted application of simulation models presents futuristic opportunities for developing decision supporting systems and agro-advisory services for scheduling best management practices for attaining sustained potato production. This review summarizes comprehensive information on the crop models being used along with their applications in the different aspects of potato production system towards a precision as well as smart agriculture.
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