The salt secretion of leaves promotes the competitiveness of Reaumuria soongarica in a desert grassland

Abstract

Background For better understanding the mechanism of Reaumuria soongarica community formation in a salt stressed grassland ecosystem, we designed a field experiment to test how leaves salt secretion changes the competitive relationship between species in this plant communities. Results Among the three species (R. soongarica, Stipa glareosa and Allium polyrhizum) of the salt stressed grassland ecosystem, the conductivity of R. soongarica rhizosphere soil was the highest in five soil layers (0–55 cm depth). The high soil conductivity can increase the daily salt secretion rate of plant leaves of R. soongarica. In addition, we found the canopy size of R. soongarica was positively related to the distance from S. glareosa or A. polyrhizum. The salt-tolerance of R. soongarica was significantly higher than the other two herbs (S. glareosa and A. polyrhizum). Moreover, there was a threshold (600 µS/cm) for interspecific competition of plants mediated by soil conductivity. When the soil conductivity was lower than 600 µS/cm, the relative biomass of R. soongarica increased with the soil conductivity increase. Conclusions The efficient salt secretion ability of leaves increases soil conductivity under the canopy. This leads the formation of a “saline island” of R. soongarica. Meanwhile R. soongarica have stronger salt tolerance than S. glareosa and A. polyrhizum. These promote the competitiveness of R. soongarica and inhibit interspecies competition advantage of the other two herbs (S. glareosa and A. polyrhizum) in the plant community. It is beneficial for R. soongarica to establish dominant communities in saline regions of desert grassland.

Reaumuria soongorica-plant model to understand drought adaptive mechanisms of xerophyte and their potentials in improving stress tolerance in plants

“…Combined with the output results of climate change models, they speculated that the distribution area of these two species will expand to the west, which has important implications on how the interactions of other desert species may change in response to climate variability. Due to efficient salt secretion ability of R. soongarica leaf, the rhizosphere soil conductivity under its canopy is higher than other two species (S. glareosa and A. polyrhizum) which leads to formation of a "saline island" and promote competitiveness of R. soongarica to inhibit interspecies competition of S. glareosa and A. polyrhizum and establish dominant communities in saline regions of desert grassland (Wang et al, 2022).…”