Influences of growing media particle size and nutrient addition on desert shrub propagation and field outplanting survival

Abstract

Optimizing growing media and nursery treatments may enhance native plant production and subsequent outplanting performance at desert field sites, yet for most species and field restoration settings, little research is available to guide selection of growing media. Using seed of the native shrub white bursage (Ambrosia dumosa (A. Gray) Payne [Asteraceae]) sourced from Sonoran and Mojave Desert field sites, we 1) evaluated seedling shoot and root growth in greenhouse media differing in particle size range (coarse vs. fine) across 4 levels of fertilizer doses; 2) assessed survival of outplanted seedlings after 2 y at field restoration sites; and 3) synthesized how land-clearing disturbance alters surface soil texture in Mojave and Sonoran desert ecosystems to inform nursery media selection. In the greenhouse, fertilizer treatment was the primary driver of seedling growth, with shoot biomass increasing 5 to 6 times and root biomass 2 times from control to high-dose treatments. Seedling shoot volume growth showed interactive effects between fertilizer treatment and media particle size. In the field, seedlings propagated in finer media exhibited higher survival than those grown in coarse media, particularly at the Sonoran site. Prior fertilizer treatment did not significantly influence outplant survival. Our synthesis revealed that land-clearing disturbance coarsened surface soils by approximately one textural class. These findings suggest that aligning nursery media characteristics with disturbed field soil textures may enhance restoration outcomes. Future research should explore whether acclimating seedlings to a broader range of soil textures during propagation improves field performance across diverse restoration settings.