Fuente: WIPO "tomato" Systems and methods for the analysis of microbial nitrogen-fixation in a plurality of plants include a gas source, a detector, a manifold, and a controller. The manifold can have a plurality of valves, wherein an individual valve is in fluid communication with an individual plant. The controller can be configured to activate the valves to sample gas from each individual plant to the detector for analysis. Also provided are methods of using the system for the automated assay of microbial nitrogen-fixation in plants and for identifying a nitrogen-fixing microbial strain.