Faba bean

Project responsible: Georg Carlsson, Department of Biosystems and Technology, SLU.

Spatial and temporal variation in growth and N₂ fixation is a major problem for the sustainability of legume cropping systems. In varietal mixtures, complementary tolerance to biotic and/or abiotic stress may lead to higher yield stability, while heterogeneity in chemical composition may be a potential disadvantage for the quality of harvested products.

To investigate the potential of varietal mixtures for increased legume cropping sustainability, three varieties of faba bean, Vicia faba, will be cultivated in field as single genotypes and in two- and three-varietal mixtures, with and without spring wheat as cereal intercrop. The experiments will be repeated in two seasons (2011 and 2012) at three locations: one at SLU Alnarp, one in Västra Götaland and one in Östergötland. This choice of field sites integrates climatic differences and includes regions in Sweden where V. faba cropping is large or increasing.

• Harvests of
  1. whole-crop forage will be performed in parts of the experimental plots at pod-fill, and
  2. harvest of grains will be done in remaining areas at full maturity.
• N₂ fixation will be measured with ¹⁵N techniques, and
• product quality will be measured by contents of protein, starch and fiber in dried whole-crop and grain samples.
• Occurrence of the fungal pathogen Botrytis fabae, causing chocolate spot disease, will be estimated by repeated visual grading and complemented by sampling of plant material for DNA-based quantification of B. fabae infections.

The project will result in a holistic evaluation of cropping system sustainability, taking both possible advantages of increased plant diversity on yield stability and potential disadvantages of heterogeneous product quality into account. The results are expected to be of high significance to the scientific community interested in ecology of plant-plant and plant-microbe interactions as well as to stakeholders, especially organic farming associations, searching means to improve agricultural sustainability.