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Work package 3 addresses three main task areas:

1) Understanding interactions between species mixtures and weeds,

2) Understanding interactions between species mixtures and aboveground pests, diseases and beneficial organisms,

3) Understanding interactions between species mixtures and belowground pests, diseases and beneficials.

Under each of these main tasks, project partners have successfully sown the respective experiments in the autumn of 2017 and/or spring of 2018. A number of mixed cropping systems are being trialed throughout Europe:

Spain (INTIA): chickpea and spring wheat, as well as lentil and spring wheat in order to evaluate foliar and belowground diseases in these systems under differing management practices and including two sowing dates. Additionally, a mixed cropping system with broccoli, floral strips and vetch was recently sown and will be evaluated for disease incidence and in order to support beneficials.

Pictures: Spring wheat chickpea/lentil mixture (above) and broccoli, floral strips and vetch (below). Photo credit: Nerea Arias (INTIA).

Germany (UniKassel): winter wheat populations, mixes of wheat populations and pure line varieties and pure line varieties are being testing in a mixed cropping system with pea in order to improve wheat baking quality in an organic management system. A mixed cropping system with winter wheat and clover as an undersowing is also being trialed under organic management comparing both plough and minimal tillage systems. The trials will evaluate both above- and belowground diseases in wheat and pea, as well as weed pressure in order to understand these interactions under such mixed cropping systems. In addition, hydroponic experiments investigating the effects of management (organic vs conventional) on early seedling vigour and root traits of twelve winter wheat composite cross populations have been completed.

Pictures: Mechanical weed control (above) and wheat/pea emergence in the field and evaluation of early seedling vigor and root traits as affected by organic and conventional management in hydroponics (below). 

Hungary (MTA ATK): root functionality of three winter wheat genotypes (one dwarf, one taller and one population) is being tested in a controlled greenhouse experiment. Measurements of electrical capacitance (EC) are completed and results will be validated with the help of root scanning. Physiological traits and soil AMF communities will also be examined to determine the effect of pea intercrop on the performance of wheat connecting it to EC measurement as a possible tool for targeted selection for mixing ability. The harvested seeds will be analysed for compositional quality properties.

Pictures: Experimental set up (top) and root density measurement with a root scanner inserted in the plastic tubes for scanning (middle and bottom). Photo credit: Péter Mikó.

Switzerland (FiBL): the field experiment to test pea and barley in a mixed cropping system has been sown and planned activities include foliar disease assessments, pathogen identification from pea samples in collaboration with UniKassel. The establishment of NGS methodology is ongoing.

Sweden (SLU): the agronomic performance of oat and pea intercropping under heterogeneous field conditions is being tested. Weed species evaluation is the main research focus and during the season weed density and species identification will be monitored and measured using drones equipped with vegetation-reflectance sensors, as well as by visual observation.

Drone picture of weed distribution in the ReMIX experimental site in Alnarp (SLU, Sweden) in September (PIC8). Photo credit: Raj Chongtham.

France (INRA Dijon): a total of 7 pea cultivars were assessed, grown either in optimal light and nutrient conditions in garden plots or under shading nets in order to characterize potential above-ground plant morphology and response to shading of contrasting pea cultivars. The parameters will then be included into the weed dynamics model FlorSys, to analyse the sensitivity of weed impacts on crop production and biodiversity to crop species parameters, with a particular focus on cereal-legume mixtures. The ultimate goal is to propose ideotypes of pea cultivars and cereal-legume mixtures that reconcile crop production, biodiversity and reduced herbicide use.

Pisum sativum cv Caméor plant sown on 14 March and sampled on 9 May 2017. Original picture (top), pixels discriminating leaf and stem area from background (middle) and leaf area distribution (bottom) estimated with image analysis.

The coming months will involve a number of field assessments in all field trials, as well as in greenhouse experiments. In addition, a field day will take place at the research field of the University of Kassel (Germany) on the 19^th June 2018, which is open to farmers, extension services and other interested parties in order to present and discuss the ReMIX project and gauge interest in mixed cropping systems.