Salt Sensitivity in Wheat

Abstract

ABSTRACrTwo selected lines of bread wheat, Triticum aestivum L, differing in their relative salt resistance, were grown in isosmotic solutions ofdifferent ionic compositions to investipte sensitivity to specific ions. Growth rates and ion accumulation were determined. The salt composition of the various solutions had little effect on the growth of the salt-resistant line, but significantly affected that of the salt-sensitive line. Specifically, solutions containing high Na' concentrations were more toxic than those containing high Cl concentrations or high concentrations of nutrient ions. There were few differences in ion accumulation between lines in a given treatment, although the sensitive line tended to accumulate more Na' than the tolerant line in the salt treatments with high Na concentrations. The (2,3,9,17,27). Examples of intraspecific variation in response to salinity have been noted in many crops (6,7,24,26,28,29). This genetic variation can provide an added tool in physiological investigations of this problem. In an earlier study (14) we compared two selections of wheat deliberately selected for salt resistance and sensitivity, respectively, to provide a high degree of contrast for physiological experiments. The study showed minimal differences between selections in water relations and gross ion accumulation, but major differences in photosynthetic and growth rates. We interpreted these results as indicative of differential responses of the two lines to specific ions, possibly related to different capabilities in ion compartmentation.The principal objective of the present study was to determine which of the two ions most frequently implicated in salinity, Na+ and Cl-, is most toxic to wheat. Attention was also paid to the effects of Ca2" and Mg2". MATERIALS AND METHODSDetails of the selection procedures used to identify saltresistant and salt-sensitive wheat, Triticum aestivum L., have been reported elsewhere (13). Fifty grams of seed from the saltresistant line (P. I. 178704) and the salt-sensitive line (P. I. 94341) were surface-sterilized by a 20-min wash in 10% bleach (NaOCl). Germination and transplantation of seedlings were carried out following standard procedures for solution culture as described previously (14) Table I. All solutions had a background of modified Hoagland solution. The solutions were as follows (parentheses indicate abbreviated designations used hereafter). The control was modified Hoagland solution (Control). The other solutions, all at an osmotic potential equal to that of 28% seawater, contained, in addition, concentrated Hoagland solution 2 (10) macronutrient salts (Hoagland); concentrated macronutrient anions, in the same proportion as in Hoagland, with Na+ as the countercation (NaHoagland); concentrated macronutrient cations, in the same proportion as in Hoagland, with Cl-as the counteranion (Hoagland-Ca); NaCl (NaCl); and Rila Marine mix, obtained from Rila Products, Teaneck, NJ (Seawater). The solutions were made up in this fashion in order to attempt to separate ...

Subsoil constraints in Vertosols: crop water use, nutrient concentration, and grain yields of bread wheat, durum wheat, barley, chickpea, and canola

“…It appears that Cl is more damaging. This contradicts findings of Kingsbury and Epstein (1986) who concluded that toxicity of NaCl solutions to the sensitive wheat was a function of the Na, rather than Cl ion. However, their findings may be affected by the use of a very high concentration of nitrate as the counter ion with Na, which itself could be toxic.…”

Sodium as nutrient and toxicant

“…Studies investigating these aspects often compare plant responses to salt provision against isosmotic provisions of non-ionic compounds such as polyethylene glycol, but these cannot provide a distinction, for example, between ion-specific effects of Na + and Cl − or K + , or between NaCl and other salts. Instead, chemically distinct, but isosmotic, salt treatments must be used (Greenway and Munns 1980;Kingsbury and Epstein 1985;Tavakkoli et al 2010). Another caveat of such work is that, since these effects occur over a longer time scale than osmotic effects, short-term experiments are not appropriate (Munns et al 2005;Tavakkoli et al 2010).…”

Application of Root Growth Endpoint in Toxicity Tests With Lettuce (Lactuca sativa)

“…The main toxic effects of salt stress, mainly of NaCl, result from at least three factors: osmotic stress, specific toxicity of ions and inducement of nutrient deficiency (Kingsbury & Epstein, 1986). With respect to osmotic potential, when the concentrations of salts in the soil increase, the water potential decreases, the turgor potential declines and the cells finally stop growing.…”