Comparison of Salt Tolerant Alfalfa(Medicago sativa) Genotypes: Germination Potential, Dry Matter Yield and Mineral Nutrient Relationships.

The need for salt tolerant alfalfa varieties is increasing in the San Joaquin Valley of California because of the increasing demand for water and the allocation of higher quality waters to salt-sensitive trees and vines. Alfalfa is planted on nearly a million acres in California and supports a large dairy industry. Being a tetraploid, there is great potential for allelic variation in salt tolerance among varieties. The objectives of this study are to compare the relative salinity tolerance of new alfalfa genotypes at two stages: germination (phase 1), emergence (Phase II) and in mature plants (Phase III). For Phase I and Phase II (focus of this poster), 19 varieties will be seeded in rows in 5 cm deep greenhouse trays with pre-salinized soils (0.5, 4,8,12,16,20 and 24 dS/m)in a split plot design replicated 3 times. The soil will be a 50:50 mix of field soil and sand and the saline waters will be dilutions of hyper-saline, subsurface drainage water in order to preserve the salt composition of the local area.  Data for germination potential will be presented. The  varieties, along with a industry standard will be planted into narrow tree pots for Phase III in which dry matter yield and mineral nutrient relationships, including Na⁺ and Cl^-  ion exclusion, will be examined.