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Title: Evaluation of alfalfa (Medicago sativa L.) populations' response to salinity stress

Author
item CORNACCHIONE, MONICA - Instituto Nacional Tecnologia Agropecuaria
item Suarez, Donald

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2016
Publication Date: 12/2/2016
Citation: Cornacchione, M.V., Suarez, D.L. 2016. Evaluation of alfalfa (Medicago sativa L.) populations' response to salinity stress. Crop Science. 57:137-150. doi: 10.2135/cropsci2016.05.0371.

Interpretive Summary: Decreasing availability of fresh water supplies for irrigation means that we must increase use of alternative waters including treated wastewater and brackish groundwater. Alfalfa is a moderately salt tolerant crop with high economic return, therefore suitable for production with lower quality water. We examined the effects of irrigation water salt type (chloride or sulfate) and five salinity levels on biomass production, salt tolerance and ion concentration of 15 alfalfa (Medicago sativa, L.) genotypes (G). There was no significant effect of salt type on shoot and root biomass production. Salinity impact was genotype-dependent. Across all genotypes, shoot biomass was significantly reduced relative to the control. The SISA14 and SW 8421S genotypes were the most productive under saline condition with the highest degree of salt tolerance. We conclude that Cl- ion toxicity does not appear to be a factor in alfalfa salt tolerance. There was a correlation between tolerance and shoot Na+, but shoot ion concentration appears to provide only a partial explanation of the relative salt tolerance of the genotypes. The high variability within genotypes indicates that future breeding programs can select and clone individual plants from existing varieties and cross individual clones for development of improved genotypes. The general information about new commercial cultivars is useful to producers and extension specialists while the information on variability and traits associated with salt tolerance is of use to alfalfa breeders.

Technical Abstract: Alfalfa is a moderately salt tolerant crop with high economic return, therefore more suitable for production with lower quality water than most high value crops. This study was conducted to examine the effects of the irrigation water salt type (ST=Cl- or SO4 2-) and five salinity levels (ECiw= 0.85, 8, 13, 18.3, and 24.5 dS/m) on biomass production, salt tolerance and ion concentration of 15 alfalfa (Medicago sativa, L.) genotypes (G). The plants were grown in a greenhouse in 60 sand tanks for 347 days under salt treatment. There was no significant effect of ST of irrigation waters on shoot and root biomass production; ST x EC and ST x G interactions were also not significant. Salinity impact was genotype-dependent (EC x G: P<0.05), except at ECiw 18.3 dS/m. Across all genotypes, shoot biomass was significantly reduced to 77%, 50%, and 27% at 13, 18.3 and 24.5 dS/m respectively, relative to the control. The SISA14 and SW 8421S genotypes were the most productive under saline condition with the highest degree of salt tolerance. This study has shown the genotypes showed similar performance in response to salinity under both salt types. Cl- ion toxicity does not appear to be a factor in alfalfa salt tolerance. Although there was correlation between tolerance and shoot Na+, the shoot ion concentration appears to provide only a partial explanation of the relative salt tolerance of the genotypes.