JAN GRENZ1, AHMAD M. MANSCHADI2, JOACHIM SAUERBORN1
1University of Hohenheim, Department of Agroecology in the Tropics and Subtropics, Germany
2Agricultural Production Systems Research Unit, Australia
Infestation with the root parasite Orobanche crenata FORSK. is one of the major biotic factors limiting profitable legume production in the Mediterranean countries. Complete yield loss can occur in the affected crops. The fertility of the parasite can lead to rapid build-up of an abundant seedbank representing a devastating infestation potential. Efforts to develop effective and practicable control methods had limited success due to the complexity of host-parasite interactions. Hence, the combination of several control approaches in an integrated strategy seems most promising. Experimental evaluation of all possible control strategies is not possible because of temporal, spatial and financial constraints.
The use of an eco-physiological model can help predict the efficacy of potential control strategies and improve the efficiency of field experimentation. Crucial aspects of host-parasite interactions include biomass partitioning among the two organisms in the short, and population dynamics of the parasite in the long term; thus, these are the most important aspects to be included in a model. A mechanistic competition model of the association faba bean - O. crenata was developed using field data from Syria and integrated into the framework of the cropping systems model APSIM (Agricultural Production Systems SIMulator). The model was evaluated using independent data sets from Turkey and enhanced by a component for simulating O. crenata seed bank dynamics. In the evaluation, APSIM proved capable to realistically reproduce courses of host and parasite growth and development. The evaluated parasite module was then used in a series of simulation studies to assess effects of tactical and strategical control measures. The model predictions were found to be in good accordance with reported field observations, where such information was available. Furthermore, they facilitated the quantitative evaluation of potential control strategies.
Further steps shall include improving the model by integration of a spatial component and expanding its scope to other biotic factors.
Keywords: Eco-physiological model, Orobanche crenata