Identification of physiological ecotypes in Hordeum jubatum based on responses to salinity stress

Abstract

Variability in salt tolerance of three populations of Hordeum jubatum was determined by analysis of growth parameters and ion relations of plants stressed with Na and Mg salts in solution culture experiments. Two populations from saline meadow habitats (Elstow and Floral) and one from a nonsaline site (University) were salinized with Na2SO4 and MgSO4 at Na:Mg molar ratios of 1:1 and 10:1. Elstow and Floral were more salt tolerant than University. University was more sensitive to the high Mg salt stress (Na:Mg, 1:1) than the high Na salt stress (Na:Mg, 10:1). The leaf area, root dry weight, root to shoot ratio under high Mg salt stress, and the root dry weight under high Na salt stress were significantly less for University plants than for Elstow and Floral plants under equivalent conditions. The greater salt tolerance of the two saline populations was correlated with restriction of Na uptake, more efficient transfer of Ca to young leaves, and the restriction of Mg accumulation in leaf tissue. The results supply evidence for physiologically distinct ecotypes of H. jubatum and indicate that habitat-correlated differences in salt tolerance have evolved in populations of this grass species. Key words: ecotype, Hordeum jubatum, ion balance, magnesium sulphate, salt tolerance, sodium sulphate, soil–plant relations, soil salinity.

Adaptation to salinity inHordeum jubatum L. populations studied using reciprocal transplants

“…This search for local adaptation was prompted by the discovery of variation among the populations in salt tolerance under controlled conditions (Wang et al 1992). The analyses of survival, growth and fecundity among populations of H. jubatum in the present study showed that they were determined by transplant site factors (i.e.…”

“…Percent survival of the UNI population at the FLO site was, however, significantly lower than that of the other two populations, which may be related to the higher Mg concentration in the soil of this site. Sensitivity of the seedlings from the UNI population to a high Mg salt treatment was shown in a hydroponic experiment (Wang et al 1992).…”

“…Properties of saturation extracts from soils sampled at three sites dominated by Hordeumjubatum. Details of methods are described in Wang et al (1992) ground biomass was 315 + 28 g m -2, root biomass was 184 + 57 g m -2 (87% in the 0-15 cm layer). The University (UNI) population was found in a former barnyard on the University of Saskatchewan campus, Saskatoon, SK (52 ° 08' N, 106 ° 37.5' W).…”

“…To more accurately determine the levels of cations and anions that are readily available to plants at these sites, ion activities (a) were estimated with GEOCHEM, Version 1.23 (see Wang et al 1992 for details). The FLO site had higher Na and Mg ion activities than ELS and the aN~/ac~ and aMg/aca also were greater at the FLO and ELS sites than at UNI (Table 1).…”

“…In previous work, we studied the effects of a mixture of MgSO4 and Na2SO4 on the growth and ion relations of three H. jubatum population from central Saskatchewan growing under controlled environment conditions (Wang et al 1992). The results showed that natural populations of H. jubatum from sites with contrasting salinity have evolved physiological ecotypes with contrasting salt tolerance.…”