Interaction of Sodium Chloride and Temperature on Germination of Two Alfalfa Cultivars¹

Abstract

Abstract Identification of laboratory conditions for isolating alfalfa ( Medicago sativa L.) plants which tolerate high temperature and high saline soil during germination and stand establishment would be useful for alfalfa improvement in and and semi‐arid environments. An experiment was designed to determine the germination percentages of ‘U.C. Salton’ and ‘Ladak 65’ alfalfa cultivars at all combinations between sodium chloride osmotic potentials (OP) of 0 to −15 bars and temperatures of 21, 27, 33, and 39 C. U.C. Salton was developed for the low desert Southwest. Ladak 65 was developed for Montana. U.C. Salton showed slight enhancement of germination when the OP was lowered from 0 to −1 bar at 21,27, and 33 C. Ladak 65 showed this enhancement only at 27 C. At lower OP's, the germination percentages declined sharply for both cultivars. There was an interaction between the effects of temperature and OP on seed germination. Cultivar‐temperature and cultivar‐OP interactions were highly significant. A statistical model was established from these data. Quadratic response surfaces were found which had high degrees of fit to the data for each cultivar. The optimal temperature‐OP combinations for germination from the response surfaces were 25.4 C at −1.1 bar for U.C. Salton and 21.4 C at 0 bars for Ladak 65. Germination trends involving salt and temperature could be useful for establishing selection pressures in alfalfa improvement programs.