Ecotypic Variation in Selected Fourwing Saltbush Populations in Western Texas

Abstract

Fourwing saltbush [Atriplex canescens (Pursh) Nutt.] seedlings from 4 western Texas tetraploid populations were established in uniform nurseries at San Angelo, Barnhart, and Marfa, Texas, in 1981 to determine relative adaptability to these respective environments. Survival and canopy development of the ecotypes were similar at the site with the most favorable growing conditions (San Angelo), but the ecotype originating nearest the planting site tended to have greatest survival and canopy size where site conditions were less favorable. Additional shrub attributes evaluated at the San Angelo site included: leaf, current year's stem, and wood phytomass, seasonal nutrient concentrations, and floral development and phenotype. Prediction equations utilizing plant canopy measurements were used to estimate weights of plant components. Variation in canopy size and yields among individual plants within ecotypes masked detection of significant (P lesser than or equal to 0.05) differences among ecotypes, but ecotypes from arid environments tended to be larger and to have greater yields than those from more mesic environments. Concentrations of crude protein (CP), phosphorus (P), and digestible organic matter (DOM) of leaves and stems were similar among the 4 ecotypes. Floral development of the ecotype from the most mesic environment progressed at a faster rate than that of ecotypes from more xeric environments. Ecotypes from xeric environments tended to have fewer staminate plants, but more plants with no sex expression than ecotypes from more mesic areas.