Cultivars of popular restoration grass developed for drought do not have higher drought resistance and do not differ in drought‐related traits from other accessions

Abstract

Numerous functional traits have been identified as key contributors to plant performance under drought. However, many of these traits, specifically root traits, are rarely considered in the development of native plant cultivars. In this study, we assessed whether cultivars of the perennial grass Elymus trachycaulus (Slender wheatgrass) developed for drought differ in (a) drought resistance (i. e. a plant's ability to maintain aboveground biomass productivity under water deficit), (b) aboveground and belowground traits, and (c) trait responses to drought from other accessions (i.e. other cultivars, wild accessions). We also evaluated trait plasticity, assessed whether multivariate trait relationships varied between control and drought conditions, and determined which suites of traits are related to drought resistance. We worked with seedlings at two developmental stages to assess whether patterns vary ontogenetically. E. trachycaulus cultivars developed for drought did not differ from other accessions in drought resistance or traits related to drought-coping strategies. The effects of drought and accession on drought resistance, traits, and trait plasticity varied by developmental stage, but relationships among traits varied little between the two developmental stages. A primary axis of functional variation related to resource acquisition (plant height, root length, root tips) was consistently associated with drought resistance. However, which secondary axes were related to drought resistance varied by developmental stage and moisture condition. Our results suggest that traits and performance of commonly used cultivars ought to be reexamined to determine whether they are actually the best candidates for revegetation projects in specific contexts.

Seed-Specific Mass and Root Growth Relate to Perennial Bunchgrass Seedling Survivorship Under Highly Limited Nutrient Supply

“…While the TRY Plant Trait database contains > 200 000 observations for seed mass, seed surface area and volume are reported far less frequently with no explicit mention of SSM; this is in stark contrast with widely reported values for massand area-standardized values of leaf and root traits ( Kattge et al 2020 ). Developing drought-tolerant perennial grasses for restoration has proven a challenging task, especially through the lens of identifying functional traits that confer stress tolerance ( Garbowski et al 2021 ). Sagebrush steppe restoration from seed is highly variable, and native species experience especially high failure rates ( Davies et al 2011 ;Clements et al 2017 ;Svejcar et al 2017 ).…”

Patterning ecological restoration after weeds

“…Recent research using high‐throughput genomics to develop predictive plant trait models shows considerable promise in rapidly accelerating selection and increasing the effectiveness of native plant materials (Jones et al 2022). Such efforts need to be broadened, as traditional plant breeding approaches often fail to release plant materials possessing the actual trait functionality needed to successfully restore degraded ecosystems (Garbowski et al 2021). An important and critical caveat is that genetic variation must exist within (native) plant species to be able to select for the desired trait(s) and the stability of gene expression conferring the trait must be independent of the environment (i.e.…”

Plant water‐use strategies predict restoration success across degraded drylands

“…Drought avoidance can also be a useful strategy, as demonstrated in a California annual grassland study where seedling root length (and presumably access to more persistent moisture) was positively related to seeding success during an exceptionally dry period (Harrison & LaForgia, 2019). A number of studies have also shown that preconditioning plants by exposing them to periodic drought before use in restoration can enhance transplant success (Kimball et al, 2017; Valliere et al, 2019), implicating a role for drought tolerance in mediating restoration outcomes, although this is not always the case (Garbowski et al, 2021). These and other studies suggest that controlled experiments linking metrics of drought responses to restoration outcomes could be valuable in identifying causal mechanisms of survival and candidate species that may perform well under arid conditions following restoration.…”

“…A number of studies have also shown that preconditioning plants by exposing them to periodic drought before use in restoration can enhance transplant success (Kimball et al, 2017;Valliere et al, 2019), implicating a role for drought tolerance in mediating restoration outcomes, although this is not always the case (Garbowski et al, 2021).…”