Relay intercropping boosts soybean recovery growth and delays nodule senescence to achieve yield advantages.

Relay intercropping soybean [ Glycine max (L.) Merr.] with cereal provides an approach to increase land productivity and improve N fixation. To explore the physiological mechanisms underlying the N fixation, leaf and nodule traits, biomass and N accumulations, nodule sucrose content, paraffin section and transmission electron microscope observations, and nodule antioxidant capacity were compared in sole and relay intercropped soybean with N levels. The growth of relay intercropped soybean was suppressed during the coexistence duration, and N addition promotes leaf growth and suppressed nodule development. After maize harvest, a boosted recovery of intercropped soybean than sole cropping notably enhanced sucrose by 20.4% allocated to the nodule. Sufficient sucrose partition delayed nodule senescence by increasing antioxidant capacity in intercropped soybeans contrast in the sole cropping. The delayed nodule senescence of intercropped soybean continuously provides ureides to the aboveground. The ureide-N in total N of intercropped soybean was 37.3% notably higher than sole cropping at the R5 stage. Finally, the adverse effects of shade on soybean growth and N fixation during the coexistence duration were compensated through the recovery growth, which benefits obtaining yield advantage of the intercropped soybean. • A boosting recovery growth increasing nodule sucrose partition in relay intercropping. • A higher sucrose partition to nodules delayed nodule senescence. • The delayed nodule senescence improves shoot ureides accumulation in relay intercropping. [ABSTRACT FROM AUTHOR]