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.

Keywords

• fertilizer; gas exchange; nitrogen-use efficiency; water-use efficiency; water stress.