Genotypic differences in root system size in white mustard in relation to biomass yield and soil nitrogen content

Abstract

Growing catch crops is one of the possible strategies to decrease erosion and nitrogen loss from soil profiles. Biomass yield and root system size have significant impacts on the soil nitrogen content. a three-year field experiment with eight varieties of white mustard (Sinapis alba L.) was established to evaluate the effects of genotype and environment on biomass yield, soil nitrogen content and rooting parameters. Significant effects of genotype were found for root length density (RLD), root surface density (RSD) and specific root length (SRL) in the plow layer (0 - 20 cm) and for root system size (RSS), measured by electrical capacitance method, during three phenological phases. Higher biomass yield in varieties with higher RLD and RSD values during ripening and a larger RSS during flowering were found in dry conditions. Relationship of the root system and biomass yield to nitrate and ammonia nitrogen content varied in different environments. We found a significant relation between the RSS and ammonia nitrogen content in more fertile environment on average over the three years. The nitrate nitrogen content was related to the RLD, RSD and SRL in favorable year at shallow soil depths (0 - 20 cm).