Above- and belowground biomass in a mixed cropping system with eight novel winter faba bean genotypes and winter wheat using FTIR spectroscopy for root species discrimination

Background and aims Legume-cereal mixtures are often characterized by higher biomass and grain yields compared to their sole crop equivalents due to complementary resource use. Little is known about the contribution of the root system to this overyielding potential and the related cultivar differences. This study investigated pure stands and mixtures of eight winter faba bean ( Vicia faba L.) genotypes and one winter wheat cultivar ( Triticum aestivum L., cv. Genius) with regard to their intra- and interspecific variation of shoot and root biomass and overyielding potential at full flowering of the bean. Methods Shoot biomass of 1 m 2 was harvested and roots were sampled with a root auger down to 0.6 m soil depth in two sampling years. Fourier transform infrared (FTIR) spectroscopy was successfully used to determine species specific root biomasses in mixtures. Statistics were performed using linear mixed effects models. Results Mixtures of winter faba bean and winter wheat overyielded more below- than aboveground. Bean genotypes grown in mixtures with wheat differed significantly in their root biomass, root:shoot ratio and overyielding potential but not in their shoot biomass. Conclusions Genotype differences in root biomass and overyielding indicate breeding potential of winter faba bean cultivars for mixed cropping.