Inherent responses to root-zone salinity in nine alfalfa populations

Abstract

Steppuhn, H., Acharya, S. N., Iwaasa, A. D., Gruber, M. and Miller, D. R. 2012. Inherent responses to root-zone salinity in nine alfalfa populations. Can. J. Plant Sci. 92: 235–248. Alfalfa productivity can be enhanced by growing crops from cultivars tolerant of root-zone salinity. Rangelander, Keho, Bridgeview, Halo, CW054038, CW064027, Rugged, Bullseye and TS4002 alfalfa plants (respectively designated Ra, Ke, Br, Ha, C8, C7, Ru, Bu and T4) were grown in sand tanks irrigated with nutrient-sulphate solutions averaging 1.53 (nutrients only), 8.03 and 15.61 dS m−1in electrical conductivity. Except for Br and C7, seedlings emerged equally under the 1.5 and 8.0 dS m−1treatments, but decreased in the 15.6 dS m−1treatment by percentages ranging from 3.1 through 29.5. Average shoot biomass among the populations respectively decreased by 49.6, 43.6 and 37.6% in the 1st, 1st+2nd, and 1st+2nd+3rd harvest-cuts as salinity increased from 1.5 to 8.0 dS m−1and by 80.1, 73.2 and 67.1% from 1.5 to 15.6 dS m−1. At 1.5 dS m−1, the C7 plants consistently produced more shoot biomass than the T4, Bu, Ha, Ru, Ra, or Ke plants. At 8 dS m−1, the relative yields of the Ha plants (scaled by their 1.5 dS m−1production) exceeded those from the other populations, although the Ha plants produced no greater actual shoot biomass than the C7 or the C8 plants.