Mixed cropping with lentils increases grain protein of wheat and barley

Spring wheat (Triticum aestivum) and spring barley (Hordeum vulgare) were mixed cropped with lentils (Lens culinaris) in five seeding ratios (100:0, 75:25, 50:50, 25:75, 0:100) at the Experimental Station for Organic Farming Kleinhohenheim, SW Germany in the years 2009 and 2010. Aim of the study was to test the effect of different mixing ratios on seed quality (crude protein: CP, thousand kernel mass: TKM) of cereals and lentils. Seed crude protein of cereals increased significantly when their proportion was reduced in the mixture with their companion crop lentil. Wheat crude protein increased from 10.3% DM (2009) and 11.0% DM (2010) in monocropping to 11.5% DM (2009) and 15.1% DM (2010) in mixed cropping with 75% lentils. Barley crude protein increased in the same way from 13.7% DM in monocropping to 15.8% DM in mixed cropping with 75% lentils. The percentage of CP in lentils, however, did not differ significantly across all mixing ratios. The TKM of cereals and lentils increased significantly when their share in the mixture was decreased. Generally, the total crude protein yield in mixtures (one cereal crop plus lentils) was significantly higher than that in cereal or lentil monocropping. Mixed cropping with lentils can thus be an option to obtain a high protein content of wheat which is important for a suitable bread-making quality, particularly in organic farming. If barley is used for feed or food, a high protein content in mixed cropping with lentils is also welcome. On the other hand, malting barley seems not a suitable partner for a mixed cropping system with lentils as the protein content might be too high.