Grain legumes for organic farming – improved disease resistance, weed competitive ability and feed quality

Danish organic production of pigs and poultry is restricted due to a lack of reliable protein crops. In organic farming, import of organic soya and other protein sources is highly restricted. So far, the demand for high protein concentrate has been covered by the allowed import of conventional feed. From the year 2005, this possibility is eliminated. To meet the requirement for protein in a feed self-sufficient organic farm with a high proportion of monogastric animals, the proportion of grain legumes in rotation should be at least 30% to 50%. Grain legumes, e.g. pea (Pisum sativum), faba beans (Vicia faba) and lupines (Lupinus sp.) can complete cereals in animal feed and are well adapted to Danish growth conditions. Besides being a valuable protein source, these grain legumes benefit the farming system via biological nitrogen fixation and by being a break-crop for cereal diseases. Therefore limitations, which reduces the maximum ratio of grain legumes crops in the organic rotation as well as their productivity, are direct limitations for the expansion of organic farming.

The biggest obstacle for an increased proportion of grain legumes in the organic rotation is presently diseases, which are accumulated in the system over time, especially soil and seed borne pathogens. In areas with longest tradition for pea growing, 10-20% of the fields are not suitable for pea production due to high levels of natural infestation of pea root pathogens. It is expected that at least 20 years is necessary before pea growing can be taken up again in these natural infested fields. This persistence of legume pathogens is therefore a threat in organic farming systems because the biological fixation of atmospheric N2 is a fundamental process for maintaining soil fertility. Although identical fungal species are isolated from the grain legumes pea, faba bean and lupine, sparse information is available on their host specialisation, pathogenicity and importance. This project will elucidate the host range of soil-borne pathogens among the grain legumes, identify resistant material, and propose a strategy to avoid unintended build up of pathogens and recommend methods for including resistance against the relevant pathogens in the VCU tests.

Various breeding methods are used when introducing resistance genes into highly adapted material. Methods involve backcrossing, where defined genes are transferred, recurrent selection involving repeated cycles of intermating and selection often used in pyramiding genes in outbreeding species and composite crosses used in selfpollinating cereals. In this project the "composite cross" method will be evaluated as a tool for selecting breeding lines with improved resistance toward root rot.

In nature, there are pea forms giving up to 32 percent protein, which make peas to an attractive GMO free protein source. With a major increase in the proportion of legumes in the diet and in the crop rotation, there is a large risk for increasing problems with feed quality. In this project, it is proposed to identify new breeding lines for protein, trypsin inhibitor activity and certain enzymes e.g. phytase and alfa galactosidase. These breeding lines will be included in breeding of new high yielding, high protein content varieties.

Weeds are a main obstacle to obtain a satisfactory yield and may result in an enhanced working load at harvest. Weed control in organic farming can be done mechanically. However, tine harrowing often seriously damages the pea plants resulting in yield reduction. It is well known that increasing the number of plants per unit of area can enhance the competitive ability of crops. In this project, the competitive ability of pea varieties and the sensitivity of phonological different pea varieties to harrowing intensity will be studied under field conditions.

Publications

Project title
VI.4 Grain legumes for organic farming – improved disease resistance, weed competitive ability and feed quality (GRAINLEG)

Project leader
Lars Bødker, Senior Scientist
Danish Institute of Agricultural Sciences (DIAS)
Research Centre Flakkebjerg, Department of Crop Protection
DK-4200 Slagelse
E-mail: lars.bodker@agrsci.dk

Project participants
Christian Andreasen, Associate Professor
Royal Veterinary and Agricultural University (KVL) Department of Agricultural Sciences, Weed Science Agrovej 10, DK 2630 Tåstrup.
E-mail: can@kvl.dk

Bjarne Jørnsgård, Assistent Professor
Royal Veterinary and Agricultural University (KVL),
Department of Agricultural Sciences, Crop Science and Plant Breeding
Agrovej 10, DK-2630 Tåstrup
E-mail: bjo@kvl.dk

Jens C. Knudsen, Plant Breeder (subcontractor under WP 1 and WP 3)
Toft Plant Breeding,
Tønderingvej 14, DK-7870 Roslev
Email: breeding@toft-group.dk

Harinder Singh, Plant Breeder (subcontractor under WP 2)
DLF-Trifolium A/S, Højerupvej 31, DK-4660 St. Heddinge
Email: has@dlf.dk