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A first set of the experiments under controlled conditions has been successfully conducted to evaluate the effects of plasticity in shoot and root morphology on plant-plant interactions. Wheat pure lines and wheat composite cross populations (CCPs) were investigated under hydroponic conditions in Germany (Uni Kassel) and in a 1m³ pot trials under greenhouse conditions in Hungary (MTA ATK).

The experiment in Germany showed that the evolution of wheat grown long-term (for 10 generations) under organic conditions resulted in better early root and shoot development compared to wheat from conventional conditions. Root types better adapted to early development in the field and ways to select for these non-destructively could be identified.

Non-destructive visualizing of roots in a 1m³ pot trials conducted in Hungary showed good correlation between root data and pre- and post-harvest aboveground biomass. First preliminary results also suggests negative pea intercrop effects on wheat root development compared to the pure stand, however, these effects had strong varietal effects. The wheat CCPs show better ability to develop roots in the presence of peas compared to pure stand varieties. In addition, the highest root system activity was measured during the late vegetative and the early flowering stage.

Fig.1 Root density measurement with a root scanner inserted in the plastic tubes for scanning. @Péter Mikó. 

Greenhouse experiments on the competitive plant-plant interactions for light, nutrients and water and interactions are under way in France (INRA-Dijon).

Field experiments for understanding interactions between species mixtures and above and below ground pests, diseases, and beneficial

Foliar diseases in most places were low due to the extreme drought. Main results are summarized in the Table below.

Similarly, foot and root rot diseases in both, cereal and legume crops were generally low. In France (INRA IGEPP) and Sweden (SLU) a general trends of reduced disease severity in mixed treatments compared to pure stands were present.

In Germany (Uni Kassel), Hungary (MTA ATK) and Switzerland (FiBL) plants were overall healthy.

In addition, a meta-analysis of mixtures and disease interactions was conducted by Wageningen University based on literature review. The meta-analysis examined the effects of intercropping on six diseases in wheat, faba bean and barley. The average disease reduction by intercropping was found in 45% cases. In wheat, significant yellow rust and powdery Mildew reductions were observed. In faba bean significant reduction of chocolate spot and Fusarium wilt, whereas intercropping had no significant effect on bean rust and yellow rust in barley.

Fig. 2 Pea-barley experiment in Switzerland (FiBL). @Benedikt Haug

Fig. 3 Experimental site in Alnarp (SLU, Sweden) showing the effect of drought in oat and pea intercrop. @ Raj Chongtham

Fig. 4 Sole wheat and wheat mixed with pea in Germany . @Johannes Timaeus