Salt Tolerance in the Halophyte Suaeda maritima L. Dum.\u2014the Effect of Oxygen Supply and Culture Medium on Growth

Gazala M Alhdad,Timothy J Flowers

doi:10.1007/s42729-020-00384-x

Abstract

Suaeda maritima is an annual species that grows in salt marshes and tolerates not only salt but also flooding, although plants are smaller at lower than at higher elevations of salt marshes. We investigated whether adventitious roots play a role in tolerance to flooding and how flooding affects ion accumulation in the shoots, a determinant of growth in this species. We examined the response of plants grown in Stout and Arnon culture solution to different periods of flooding at different salinities and verified our results with plants grown in other culture solutions (Hoagland and Yoshida). We measured growth, photosynthesis and estimated stomatal frequency as well as the accumulation of Na+, Ca2+, Mg2+ and K+: plants grew and photosynthesised optimally in 200-mM Na+ (in Stout and Arnon solution), but the optimal concentration for growth increased to 450 mM when in Yoshida solution. Flooding always decreased growth, but had little effect on Na+ concentrations. Although plants produced adventitious roots, their mass decreased rather than increased with flooding. The decrease in production of adventitious roots under flooded conditions suggested that they were not important in the tolerance of this species to submergence—an unusual response compared with the general response of flooding-tolerant plants.

Highlights

Coastal salt marshes vary in salinity and in elevation and in the frequency of tidal inundation
We have investigated whether adventitious roots play a role in tolerance to flooding in S. maritima, using plants grown in culture solutions
Flooding reduced growth in Hoagland and Yoshida solution producing a similar pattern of response to that in Stout and Arnon solution

Summary

Introduction

Coastal salt marshes vary in salinity and in elevation and in the frequency of tidal inundation. With the increases in sea level consequent upon climate change, tolerance of flooding is likely to be an important factor in the zonation of plants on salt marshes (Tabot and Adams 2019) Suaeda maritima grows across salt marshes, but plants are smaller at lower than at higher elevations (Wetson and Flowers 2010; Alhdad et al 2013). Such differences in growth can be replicated in plants cultured in a. Other possibilities are the cost of compartmentation of increased shoot Na+; the consequences of reduced shoot K+ concentrations relative to plants growing at higher redox potentials (Wetson and Flowers 2010), investment in antioxidants (Alhdad et al 2013) and the possible

Methods

Results

Discussion

Conclusion