Crop type determines the relation between root system architecture and microbial diversity indices in different phosphate fertilization conditions

Synthetic phosphate fertilizers are frequently used in agriculture and their overuse can significantly increase production costs and cause negative environmental impacts. Soil phosphorus (P) availability can be increased by the contribution of the rhizosphere microbiota associated with the plant root system. This work aimed to evaluate the effect of different phosphate fertilization conditions on maize and sorghum genotypes. Four com-mercial genotypes of maize and four of sorghum were cultivated for two seasons under seven treatments, no addition of P fertilizer, and 50 and 100 kg P2O5 ha-1 of two rock phosphate (Itaf ' os and OCP) and triple su-perphosphate. During flowering time, the root system was collected according to the Shovelomics' method and analyzed by a modified version of Digital Imaging of Root Traits (DIRT) system. The modifications made the root system architecture analyses less error-prone and more effective. Moreover, three diversity indices, Shannon-Wiener (H '), Simpson (1-D) and Chao1, were calculated based on the bacteria abundance and richness. The type of crop followed by the genotype and fertilizer were the main factors that affected the root system, grain yield, genetic diversity and abundance of microorganisms. The most productive genotypes had higher root angle and area, increased foraging on the soil surface and P acquisition. Maize presented higher microorganism di-versity, root angle and foraging traits while sorghum presented higher abundance of specific taxa, a narrower root angle and smaller foraging. The combined use of less reactive P sources, which could be more soluble over time by the physicochemical processes and soil microbiota activity, together with more efficient genotypes might reduce the amount of soluble phosphate fertilizers applied annually to crops.