Limits imposed by salt to the growth of the halophyte Sesuvium portulacastrum

Abstract

The growth of the halophyte Sesuvium portulacastrum, commonly known as sea purslane, is impeded by NaCl only at high (600–1000 mM) concentration. Therefore, the goal of this investigation was to identify the mechanisms which set the limit of the salt resistance of S. portulacastrum. 21‐day‐old cuttings were grown for 45–50 d under split‐root conditions in which one half of the root system was immersed in complete nutrient solution supplemented with 800 mM NaCl, while the other half was immersed in a NaCl‐free medium, containing all nutrients or being deprived of potassium or calcium or nitrogen. Using this approach, we demonstrate that K+ and N uptake was impaired in roots exposed to NaCl. Concerning Ca2+, there was no indication of uptake inhibition by NaCl. However, restriction of K+ uptake by roots was compensated by an increase in the K+‐use efficiency, so that growth was not inhibited. Concerning N, our analysis shows that NO$ _3^- $ and/or NH$ _4^+ $ uptake, but not their assimilation, was limited by salt treatment. Thus, we conclude that at high salinity levels, the growth of S. portulacastrum is limited by the restrictions imposed by NaCl on N uptake, perhaps in addition to inhibiting effects of excessive Na+ accumulation in shoot.

Effect of sodium chloride on the response of the halophyte species Sesuvium portulacastrum grown in mannitol-induced water stress

“…This observation is in accordance with an improvement of tissue hydration and is in conformity with the previously observed salt-accumulating character of S. portulacastrum and its capacity to sequester Na + in the vacuoles for osmotic adjustment (Messedi et al 2004). In halophytes, the involvement of Na + in osmotic adjustment has been amply highlighted, if it is assumed that it is mainly present in the vacuoles and that this compartment occupies approximately 90% of the total cell volume.…”

“…In a previous work (Messedi et al 2003), we observed that the growth and tissue hydration in S. portulacastrum were maximal in the presence of 100-400 mmol l -1 NaCl. Additionally, using a split root system (Messedi et al 2004), we demonstrated that even at high salinity levels (800 mmol l -1 NaCl), the growth of S. portulacastrum is limited by the restriction imposed by NaCl on N uptake rather than ionic and/or osmotic stresses.…”

“…In previous work we showed that S. portulacastrum is able to express high growth potential, even under severe salinity (Messedi et al 2003. In fact, salt-induced growth stimulation in S. portulacastrum may be maintained in the presence of 800 mmol l -1 NaCl if a part of the root system is protected from the effect of salt (Messedi et al 2004). As with salinity, even when subjected to long-term water deficit, S. portulacastrum is known to retain its growth potential and nutrient acquisition systems and exhibits a dramatic accumulation of proline (Slama et al 2006).…”

Evaluating Salt Tolerance of 14 Barley Accessions from Southern Tunisia Using Multiple Parameters

“…Similar studies were also conducted on other species such as wheat (Bhatti, Ali, Bakhsh, Razaq, & Jamali, 2004), oat (Zhao, Ma, & Ren, 2009) and rice (Gain et al, 2004;Razzaque, Talukder, Islam, Bhadra, & Dutta, 2009) and showed that the tiller and the leaves numbers decreased under the effect of salt stress. Several works, using split root system approaches on glycophyte and halophyte species, have demonstrated that nutritional disturbances caused by salt are implicated in the restriction of the growth under salinity stress (Messedi, Labidi, Grignon, & Abdelly, 2004;Attia, Karray, Mokded, & Lachaâl, 2008). According to Majd and Shahbazi (1996), this reduction is due to the effect of Na + and Cl -ions on the cellular division in the shoot apical meristem which affecting the formation of the floral and the auxiliary buds, and then on the final number of leaves and tillers produced.…”

The integration of activity in saline environments: problems and perspectives

“…for K + -specific protein activation (Clarkson and Hanson 1980;Flowers and Läuchli 1983). In the usual way of calculating 'use efficiency' as the inverse of tissue concentrations, potassium use efficiency increases along with decreased uptake (Messedi et al 2004). This once broadly recognised 'potassium-sparing' effect of Na + has, seemingly, been reinterpreted (or misinterpreted) as a deleterious effect of Na + on transporters associated with determining 'selectivity'.…”