Macroaggregates of loam in sandy soil show little influence on maize growth, due to local adaptations of root architecture to soil heterogeneity

Abstract

Abstract Aims Root hairs and lateral growth are root traits among many which enable plants to adapt to environmental conditions. How different traits are coordinated under local heterogeneity, especially when two or more environmental factors vary in space, is currently poorly understood. We investigated the effect of heterogeneity on root system architecture of maize in response to the presence of loamy macroaggregates, which come along with both, increased penetration resistance and nutrient availability, i.e., two important environmental factors shaping root system architecture. The comparison between a mutant with defective root hairs and the corresponding wild type made it possible to investigate the importance of root hairs in the adaptation strategies of plant roots to these factors. Methods Changes in root growth and root distribution with respect to macroaggregates were investigated using X-ray computed tomography. The wild-type of Zea mays L. was compared with the root hair defective mutant (rth3) to investigate the importance of root hairs in addition to adaption of root architecture. Results The presence of aggregates lead to increased root length and branch densities around aggregates, while only a few roots were able to grow into them. Thereby, wildtype and rth3 were influenced in the same way. Aboveground biomass, however, was not affected by the presence of macroaggregates, as compared to controls with homogenously distributed loam. Conclusions Macroaggregation of loam in sandy soil shows little influence on maize growth, due to local adaptations of root architecture to the heterogeneity in nutrient availability and penetration resistance caused by the aggregates.