Salt tolerance and salt uptake in diploid and polyploid buffalograsses (Buchloe dactyloides)

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Abstract
Seed samples of diploid, tetraploid, and hexaploidbuffalograss (Buchloe dactyloides) were collected from locations over a geograptucal latitudinal gradient from San Luis Potosi, Mexico to Lincoln, Nebraska in the United States. Seed samples and samples of vegetatively propagated clones were tested for salt tolerance and salt uptake. Under nutrient solution culture, young shoots separated from the established buffalograss clones were found to be more tolerant to salt than the seedlings. Significant difference was found in the percentage of seedling survivorship among the populations. Substantial genetic variation of salt tolerance was detected among the vegetatively propagated clones within buffalograss populations. Over all, the buffalograss can he considered to be a moderately salt sensitive species. Its wealth of genetic variation of salt tolerance represents a potential for rapid salt tolerance selection response. A salt exclusion mechanism was found in the tolerance mechanism of the buffalograss. A greater sodium (Na) concentration was found in the root tissue than in the shoot tissue, suggesting a preferential exclusion of Na taken up by the shoots. The negative correlations between the plant tissue potassium (K) concentrations and Na/K ratios indicate a partial substitution of K by Na, and there was a less substitution of K by the more salt tolerant plants than the less tolerant plants. Differential susceptibility to calcium (Ca) disorders at high Na/Ca levels was detected between the salt tolerant and salt sensitive buffalograss genotypes.