Physiological Responses of Wild and Cultivated Barley to the Interactive Effect of Salinity and Iron Deficiency

Sabeh Yousfi,Mohamed Gharsalli,Hayet Houmani,Chedly Abdelly,Fethia Zribi

doi:10.5402/2012/121983

Abstract

Literature on the separate effects of salinity and inadequate Fe supply on plant growth and nutrient uptake, concentration, and distribution is abundant but little is known about the interactive effects of these two abiotic constraints. Here, we investigated the interactive effect of iron availability and salinity on physiological responses of cultivated and wild barley (Hordeum vulgare and H. maritimum resp.). Seedlings of both species were grown for 9 days, under complete nutrient solution with or without iron supply. Then, NaCl treatment was applied at different concentrations (0, 100, 200, and 300 mM) for 60 hours. After salt exposure, shoot water content of H. vulgare was significantly reduced as compared to H. maritimum. Furthermore, Na+ accumulation in shoots increased parallel to increasing NaCl concentration in the medium. However, the increase was significantly higher in H. vulgare than in H. maritimum. These responses were associated with lower Fe absorption efficiency photosynthetic parameters in both species. The reduction was significantly higher in cultivated than in wild barley. Moreover, phytosiderophore exudation was enhanced in both species by direct (iron free medium) or indirect iron limitation (salt-induced iron limitation). Such a stimulation of phytosiderophore release was genotype and salt level dependant.

Highlights

It is well documented that hindrance effect of high soil alkalinity on plant growth is related to nutrients availability limitation; of iron [1]
Our objective was to investigate a comparative study between two graminaceous species differing by their salinity tolerance: H. vulgare a glycophyte species and H. maritimum a halophyte native of salted soils where it significantly contributes to the annual biomass production in such ecosystems [12], in order to know the impact of salinity on iron uptake and on the inducible mechanism of its acquisition and to examine if the eventual impact is dependent on the tolerance of plant to salinity
Addition of salt to the nutrient medium with Fe supply slightly decreased chlorophyll contents with increasing salt stress level, but the reduction was more significant in H. maritimum than in H. vulgare (Table 1)

Summary

Introduction

It is well documented that hindrance effect of high soil alkalinity on plant growth is related to nutrients availability limitation; of iron [1]. Jumberi et al [5] found that the relative uptake of iron by barley and rye decreased with increasing soil sodicity. This result allows the suggestion of several hypotheses. It is possible that in the sodic soil, which has a high pH and Na+ concentration, (i) the availability of iron is reduced either by the alkaline pH or by the formation of insoluble iron-phosphate complexes, (ii) the synthesis pathway of the iron chelators and uptake systems for iron was partially inhibited at high salinity, (iii) the effective complexation of iron by chelators could be negatively affected by the high ionic strength of the growth medium

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Conclusion