Intraspecific diversity of cereals – root architecture and quantification of root carbon inputs

Crop diversification as an agricultural practice has been proposed for increasing carbon (C) storage in agricultural soils. Plants allocate C belowground differently depending on biotic and abiotic factors, which can be observed through variations in root architecture and root economics space. Root exudates are an important source of organic matter inputs to soils, and their composition is an important driver of plant-soil interactions in the rhizosphere. However, little is known about whether varieties of the same species differ in terms of organic matter inputs and thus their potential influence on soil functioning (e.g., C sequestration potential), and whether there is a relationship between root architecture and the composition of exudates. In a growth chamber experiment, we investigated root exudate compositions of commonly used cereal species and varieties, and their architectures were determined. Cereals were grown in rhizoboxes (40.2 x 26.1 x 3cm) for 21 days with 12-h light, 24°C and 19°C during the day and night respectively with a relative humidity of 60%, and included: 3 oat (Avena sativa L., varieties Galant, Fatima, and Ferry), 2 wheat (Triticum aestivum L., varieties Informer, and Julius), and 2 barley (Hordeum vulgare L., varieties Anneli, and SW Judit). Root system development and architecture were quantified from pictures taken regularly during the growth period, while exudate composition, collected via the soil-hydroponic-hybrid approach, were determined by ¹H Nuclear Magnetic Resonance. Root system architecture varied significantly across species, while within species variation was only significant for barley and wheat. This coincided with patterns of significant variations in exudate profiles across and within species. Furthermore, our results show both how root systems and organic matter inputs can vary depending on choice of genotype within commonly grown cereals. In this presentation, we will discuss the possible link between C input and root architecture, as well as the use of intraspecific diversity in cereals to increase C storage in agricultural soils.