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Title: Emergence, forage production, and ion relations of alfalfa in response to saline waters

Author
item CORNACCHIONE, MONICA - University Of California
item Suarez, Donald

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2014
Publication Date: 7/29/2014
Citation: Cornacchione, M.V., Suarez, D.L. 2014. Emergence, forage production, and ion relations of alfalfa in response to saline waters. Crop Science. 55:444-457. doi: 10.2135/cropsci2014.01.0062.

Interpretive Summary: Alfalfa (Medicago sativa L) is an important crop utilized in regions under irrigation commonly impacted by salinity. Its high water use makes it difficult to sustain production in regions of the world with scarce fresh water supplies. In this study we evaluate the effect of salinity, as a continual process, from emergence to mature plant growth in successive harvests for 4 alfalfa cultivars with purported salt tolerance. We studied emergence, biomass production, salt tolerance and evaluated shoot specific ion compositions as potential physiological mechanisms. We utilized irrigation waters ranging from 3.1 to 30 dS/m of electrical conductivity (ECiw) imposed at planting date. Relative emergence (%) decreased above EC 12.7 dS/m, and at EC 30 dS/m there were no survivor plants. Absolute and relative accumulated biomass from six harvests decreased for ECiw above 12.7 dS/m (6.0 dS/m in the saturation extract, ECe). Salado cv showed the least reduction in biomass at elevated salinity. The ability of Salado to maintain low shoot-Na was the mechanism most associated with salt tolerance. We conclude that saline waters with resultant ECe values of up to 6 dS/m can be used throughout the total production cycle (planting to multiple harvests) without significant yield loss for 3 of the 4 cultivars evaluated. This information is of use to producers, extension specialists and irrigation specialists considering the use of saline water for forage production.

Technical Abstract: Alfalfa (Medicago sativa L) is an important crop utilized in regions under irrigation commonly impacted by salinity. In this study we evaluate the effect of salinity, as a continual process, from emergence to mature plant growth in successive harvests. We studied emergence, biomass production, salt tolerance and shoot ion composition as potential physiological mechanisms in four non-dormant salt tolerant cultivars: Salado, SW 8421S, SW 9720 and SW 9215. Irrigation water salinity dominated by sodium sulfate ranging from 3.1 to 30 dS/m of electrical conductivity (ECiw) was imposed at planting date. Plants were grown in outdoor sand tanks in Riverside CA, for 300 days. Relative emergence (%) decreased above EC 12.7 dS/m, and was reduced to 53 % and 13.4% at 18.4 and 24 dS/m, respectively. At EC 30 dS/m there were no survivor plants. Absolute and relative accumulated biomass from six harvests decreased for ECiw above 12.7 dS/m (6.0 dS/m in the saturation extract, ECe). Plants grown at 18.4 and 24 dS/m produced 68% and 30% respectively of the control biomass. Salado showed the least reduction in biomass at elevated salinity. Increasing salinity increased shoot Na+, total-S, Cl-, Mg2+ and P and decreased K+ and Ca2+. The ability of Salado to maintain low shoot-Na was the mechanism most associated with salt tolerance. Saline waters with resultant ECe values of up to 6 dS/m can be used throughout the total production cycle (planting to multiple harvests) without significant yield loss for 3 of the 4 cultivars evaluated.