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During this last period an important experimentation activity was conducted in the WP4. Trial designs, assessment procedures and some genotypes have been shared among partners and adjusted for better comparability. 21 trials were set up by 12 partners within this first year of the ReMIX project. T4.1 is addressed by 11 trials, T4.2 by 16 trials and T4.3 by 9 trials. A lot of these trials were set up in order to be cross-cutting to different tasks of WP4.

Experiments serve particularly the three objectives:

(i) to identify selection criteria (traits) and ideotypes to breed for species mixtures,

(ii) to estimate the mixing ability of lines and populations, including traditional varieties and

(iii) to screen existing varieties and germplasms for their suitability for species mixtures.

Field trial in Fislisbach, Switzerland (2018) @Maike Krauss (FiBL).

Field trials in Hungary (2018) @MTA ATK Hungary

Field trials in Hungary (2018) @MTA ATK Hungary

A first version of the key-trait database was generated and distributed among the partners to contribute traits to the database. Partners identified the top 3-5 intercropping-related key traits per crop species combination that they consider most relevant to assess in the field trials.

Adjustment and calibration of existing FSP models for cereals (wheat, maize) and legumes (pea, faba) were conducted and detailed measurements were carried out on mechanisms for complementary resource capture, including light and nutrients, enabling an analysis of complementary mechanisms for capturing light and nutrients in relation to species traits.

The new phenotyping robot arrived in September 2017 and was first tested on a wheat sole crop trials.

Phenotyping robot at INRA experimental farm (Toulouse) @Philippe Burger, Agrophen platform, Inra Toulouse

A scientific review “Do we need specific breeding for legume-based mixtures?” in Advances in Agronomy was published. This quantitative synthesis of the literature was performed on the predicted correlated response to selection in pure stand vs. mixed stand. This point for a positive relationship between the genetic gain in the two conditions, but a loss of 40% of efficiency when breeding in pure stand for mixed stand conditions. In parallel, the theoretical evaluation of three selection schemes for inter-specific assembly ability was done and the comparison of the expected gains estimated. The selection usually performed on single-species progeny tests showed that when selection is on lines subjected to genetic effects of competition / facilitation the selection on the performances in pure culture does not allow to obtain a genetic gain on the performance of the mixture. A paper in G3 Genes, Genomes, Genetics will also be published.

For the next period, the plans are:

(i) continue trials, start data analyses,

(ii) continue key-traits identification and feed database ,

(iii) continue to obtain appropriate data to feed the models,

(iv) continue the comparison of selection schemes and apply developed wheat and pea FSP models to wheat-pea mixed stand,

(v) Test new phenotyping robot on wheat-pea mixed stand