Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 2013
Publication Date: January 17, 2013
Citation: Cornacchione, M.V., Suarez, D.L. 2013. Yield and ion relations of alfalfa (Medicago sativa L.) in response to irrigation with saline waters. In: Plant Abiotic Stress and Sustainable Agriculture: Translating Basic Understanding to Food Production. January 17-22, 2013. Taos, New Mexico. p. 47. Technical Abstract: Alfalfa is a major forage crop utilized in arid and semi-arid regions under irrigation; these regions are commonly impacted by saline water and soils. Four commercial non-dormant, purported salt tolerant Alfalfa cultivars 'Salado', 'S&W8421s', 'S&W9720' and 'S&W9215' were grown in 24 outdoor sand tanks in Riverside CA, with irrigation water (sodium sulfate dominated) at EC: 3.1 (control), 7.2, 12.7, 18.4, 24.0 and 30 dS/m, imposed at planting date. We evaluated four replicates per treatment for yield, ion composition and physiological parameters. Forage yield of cultivars per harvest (relative to control; average from seven harvests) was significantly influenced by salinity above EC 12.7 dS/m except 'S&W 8421s' that showed reduction with EC above the control. There were no significant yield differences among cultivars at EC 7.2 and 12.7 dS/m. At EC 18.4 dS/m Salado had the highest yield and differed significantly from the rest. At 24 dS/m the yield decreased for all cultivars but Salado showed the least reduction. At EC 30 dS/m (highest level) there were no survivor plants. The photosynthetic rate (Pn), leaf transpiration rate (tr) and leaf stomatal conductance (gs) all showed a decrease with increasing EC. Potassium shoot concentrations decreased in all cultivars with increasing salinity. Chloride increased from the control to all other salinity levels and was lowest for Salado at elevated EC, but there were no significant differences among cultivars. Sodium shoot concentration increased in all cultivars with increasing salinity, however Salado maintained significantly lower concentrations at all salinity levels (up to 40% less than the mean of the other cultivars at 18.4 dS/m). These results suggest that Na+ exclusion is an important factor in determining alfalfa salt tolerance.