Selecting Atriplex canescens for Greater Tolerance to Competition

Abstract

Success in establishing fourwing saltbush [A triplex canescens (Pursh) Nutt.] is often limited by competition from associated vegetation. Fourwing saltbush is reported to have abundant natural genetic variation, hence selection for plant vigor or competitiveness may be an effective tool for cultivar improvement. We observed distinctive within-accession variation in the apparent ability of founving saltbush seedlings to tolerate competition from sideoats gama [Bouteloua curtipendula (Michx.) Torr.] in a 1982 field planting. Superior and inferior parental saltbush phenotypes in the field planting were cloned in 1984 by rooting stem cuttings, and the cloned propagules were transplanted into plots with or without competition to test the hypothesis that the competitiveness trait was genetically controlled. Survival and canopy development of superior and inferior clones planted at the same time in competition regimens were similar, suggesting that the parental phenotypes were not genetically different in their ability to tolerate competition. Differences observed in the parental phenotypes may have been environmentally induced, or genetic differences in the clonal material may have been masked by using rooted cuttings rather than seedlings, by excessive competitive pressure in the competition regimens utilized, or both. Clones from the 2 parental phenotypes performed similarly when transplanted into competitionfree regimens in November when growing conditions were favorable, but canopy development of clones from superior parental phenotypes exceeded that of those from inferior parental phenotypes when transplanted into competition-free regimens in April when growing conditions were poor.

Fourwing Saltbush Seed Yield and Quality: Irrigation, Fertilization, and Ecotype Effects

“…Pistillate and staminate plants of 4 tetraploid (J. Barrow, USDA-Agricultural Research Service, personal communication, February 2004) western Texas ecotypes of fourwing saltbush that exhibited superior seed and pollen production in common nursery and field plantings at the Texas A&M University Agricultural Research & Extension Center near San Angelo, Texas, were propagated vegetatively in autumn 1986 from stem cuttings (Ueckert and Petersen 1991). The use of such clones should be advantageous because superior traits for seed orchard plants (seed and pollen production) show constancy from year to year (McArthur et al 1978).…”

“…It would also eliminate the inconvenience of locating acceptable wildland stands and obtaining permits or permission to harvest seeds (McArthur et al 1978). Fourwing saltbush can be vegetatively propagated (cloned), and this facilitates the selection and increase of plants with desirable traits (Wiesner and Johnson 1977;McArthur et al 1978;Ueckert and Petersen 1991). McArthur et al (1978) proposed a design for fourwing saltbush seed orchards and suggested that seed orchards could be a profitable enterprise on marginal agricultural lands.…”