Abstract
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.