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Objectives

Based on quantitative genetics, ecology, ecophysiology and agronomy, this WP integrates theoretical and experimental approaches to develop new breeding methods for crop mixtures. Experiments performed on diverse crop mixtures will focus on a common list of morpho-physiological traits, with the aim to define ideotypes to exploit in breeding or screening varieties and other genetic resources for adaptation to mixed cropping. Yield gains provided by different selection strategies estimated according to quantitative genetics theory and from actual selected material will shed light on optimal breeding strategies. Also, we will study new phenotyping approaches. Overall, this WP will contribute to develop original breeding strategies, schemes and procedures aimed to breed effectively for species mixtures.

Experiments will be conducted in multi-site field trials to test/screen varieties, breeding lines, pre-breeding population, landraces and heterogeneous populations (including traditional varieties) of cereals (bread and durum wheat, barley, triticale, maize) and legumes (pea, faba bean, lupine, lentil). Research will also focus on lucerne and clovers used as companion species, i.e., species used to produce ecosystem services but not harvested.

Through participatory approaches, farmers will contribute to selection trials and to identify key traits to incorporate into on-farm breeding criteria. Also, there will be a degree of cultivation intensities ranging from conventional to organic farming.

Field experiments for assessment and identification of key traits

With the above objectives to be achieved, field experiments have been set up in Hungary, Greece, Germany, France, the Netherlands, Italy and Switzerland for the assessment and identification of key traits during the 2017-2018 season. Species mixtures tested are wheat-pea, wheat-white lupine and wheat-faba bean and the respective sole crops. Other cereals tested include triticale, barley and durum wheat. Assessments comprise ground cover, plant growth stages, heading dates, plant height, biomass, foliar and foot diseases, architectural traits, yield as well as onset of flowering and maturity date to identify cereal and legume materials with the same grain maturity. Other measurements, such as yield components, aboveground development, height measurements, radiation interception and belowground biomass will also be conducted by some partners.

Field trials in Hungary.

2018 field trial in Fislisbach, Switzerland.

Field trial in Lelystad (Netherlands).

Field trial in Gif sur Yvette (France).

In silico assessment of ideotype performances

An important objective in WP4 is to use FSP models to determine optimal trait combinations for intercropping that can be used as a guide for breeding efforts, as well useful when developing phenotyping tools. Building an FSP for intercropping requires the coupling of two separate FSP models for each species, which makes it important to start with a well-defined exemplary intercrop system that combines two criteria: (i) sufficient data can be generated to feed the model and (ii) FSP models need to be available for the species in question.

Based on the availability of models at WU (wheat FSP) and INRA (pea FSP), the partnership has decided to concentrate on the wheat-pea intercropping, focusing on aboveground traits. The two models will be combined over the coming year for a wheat-pea intercrop FSP, which will benefits of the numerous ongoing wheat-pea trials, and will be fed by data collected on the traits agreed by all partners involved.

Screen and estimate line/population performances in species mixtures

Phenology field experiments have been established in a few regions (e.g. Italy) to identify legume-cereal combinations with similar crop maturity – as required when producing a cereal-legume grain crop – for use in future breeding experiments. Experiments have been set up in different countries (Hungary, Greece, Switzerland, Germany, France) including different pea and cereal (triticale, barley, durum wheat and bread wheat) genotypes having different diversity levels (varieties, mixtures, landraces, populations) in order to screen and estimate line/population performances in species mixtures. A large breeding experiment including hundreds of pea lines selected in different conditions (pure stand and association with different cereal species) is going to be set up in Italy.

Pea and wheat intercrop Isard-Yecora (top), Olympos-Yecora (bottom) in Greece.

New high-throughput phenotyping methods (NHTP)

A phenotyping robot with RGB cameras, multispectral cameras and LiDAR has been tested at INRA-Toulouse (France) on a wheat trial. A wheat-pea intercropping trial is planned for the 2018/19 season where canopy cover and height growth will be monitored with an emphasis on identifying each crop contribution to the mixture. 

The phenotyping robot at INRA experimental farm (Toulouse).

Images acquired at 730 nm with the two multispectral cameras over a wheat microplot (10 rows).