RootBoost: towards a robust stimulation of plant root growth

English. Root systems play a major role in the growth and health of cultivated plants. They are in constant interaction with numerous microorganisms and are at the core of the water and mineral nutrition of plants. On the other hand, the application of agricultural inputs such as biostimulants and biopesticides aims at improving the growth and natural defenses of crops. Typically, biostimulation improves plant nutrition processes by enhancing the nutrients use efficiency or the resistance to abiotic stresses such as drought. However, the efficacy of biocontrol or biostimulation products varies depending on the pedoclimatic conditions, which may limit their widespread use. Soil microbial communities (microbiota) represent another factor of variability. Additionally, some microbiota members have biostimulant properties as well as bioprotection traits against phytopathogens through complementary mechanisms. In this context, the RootBoost project aims at addressing two issues related to the bioactivity of Plant Growth-Promoting Bacteria (PGPB) in agriculture and microbe-microbe interactions. The first part focuses on the bioactivity of a strain of Bacillus velezensis – with known biostimulant and/or bioprotection properties such as GA1, FZB24 and FZB42 – on the development of Solanum lycopersicum (L.). Our hypothesis is that the biostimulant and induced systemic resistance (ISR) activities of this strain could be modulated when applied in combination with another microorganism and/or selected organic substances. To address this question, we plan to conduct experiments under diverse conditions and assess the impact of the treatments on root development and the related microbial communities in a standardized substrate. Complementarily, the second part focuses on the robustness of plant growth promotion after PGPB application in contrasted soil conditions. In practice, contrasted samples of Walloon soils will be first characterized in terms of their physicochemical properties and microbiota. Subsequently, soils will be used as a growth substrate to evaluate how the biostimulant and ISR activity of B. velezensis on Triticum aestivum (L.) may change in the presence of contrasting microbial communities.

Projet PHENIX Biocontrol ULiège-SPW