Strawberry Yield Improvement by Hydrogen-Based Irrigation Is Functionally Linked to Altered Rhizosphere Microbial Communities.

Molecular hydrogen (H 2 ) is crucial for agricultural microbial systems. However, the mechanisms underlying its influence on crop yields is yet to be fully elucidated. This study observed that H 2 -based irrigation significantly increased strawberry ( Fragaria × ananassa Duch.) yield with/without nutrient fertilization. The reduction in soil available nitrogen (N), phosphorus (P), potassium (K), and organic matter was consistent with the increased expression levels of N/P/K-absorption-related genes in root tissues at the fruiting stage. Metagenomics profiling showed the alterations in rhizosphere microbial community composition achieved by H 2 , particularly under the conditions without fertilizers. These included the enrichment of plant-growth-promoting rhizobacteria, such as Burkholderia , Pseudomonas , and Cupriavidus genera. Rhizobacteria with the capability to oxidize H 2 (group 2a [NiFe] hydrogenase) were also enriched. Consistently, genes related to soil carbon (C) fixation (i.e., rbcL , porD , frdAB , etc.), dissimilar nitrate reduction (i.e., napAB and nrfAH ), and P solublization, mineralization, and transportation (i.e., ppx-gppA , appA , and ugpABCE ) exhibited higher abundance. Contrary tendencies were observed in the soil C degradation and N denitrification genes. Together, these results clearly indicate that microbe-mediated soil C, N, and P cycles might be functionally altered by H 2 , thus increasing plant nutrient uptake capacity and horticultural crop yield.