Morphological and physiological responses of spatholobus suberectus dunn to nitrogen and water availability

Abstract

A pot study was conducted to elucidate morphological and physiological responses of Spatholobus suberectus Dunn accessions to four nitrogen application rates (0, 10, 20, and 30 mmol L–1) and two watering regimes (daily irrigation and irrigation every 10 d for a month). The results showed that water deficit led to marked decreases in leaf water relations and photosynthetic parameters regardless of the N treatments. Under drought conditions, the reductions in net photosynthesis occurred mainly due to stomatal factors. Although the leaf N content and stem mass ratio were positively correlated with N application, other morphological and physiological characteristics were negatively correlated or nonsignificantly correlated with N application under limited water supply. As the root nodules of S. suberectus can provide sufficient N supply, and high N applications made S. suberectus plants more vulnerable to drought stress, we suggest that no N supplement is required for S. suberectus seedlings.