Shoot Biomass production among accessions of Medicago truncatula exposed to NaC1

Increased salt tolerance would improve utilization of salt-sensitive crop plants such as alfalfa (Medicago sativa L.). In order for selection for salt tolerance to be more efficient, it is useful to know whether improved productivity under saline conditions is due to unique physiological responses to salinity or merely the carry over of increased yield that was selected for in a nonsaline environment. Medicago truncatula Gaertn., a self-pollinated relative of alfalfa, was used to examine the response of specific genotypes across a range of salinities. This was done by evaluating the change in fresh shoot biomass production of greenhouse-grown mature plants and seedlings of different accessions of M. truncatula in response to four levels of salinity imposed as NaCl. Those accessions with the highest fresh shoot biomass production under nonsaline irrigation also had the highest fresh shoot biomass production under all salinity levels. The high correlation between an accession's fresh shoot biomass under nonsaline and saline irrigation indicate no unique physiological adaptation to salinity in the accessions of M. truncatula evaluated.