Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2023
Publication Date: 5/13/2023
Citation: Quigley, K.M., Ziegenhagen, L.L., Hamerlynck, E.P. 2023. Seed-specific mass and root growth relate to perennial bunchgrass seedling survivorship under highly limited nutrient supply. Rangeland Ecology and Management. https://doi.org/10.1016/j.rama.2023.04.005.
Interpretive Summary: Seed mass is known to be an important trait for successful seedling establishment and might therefore be an important plant feature to select to improve rangeland restoration efforts. However, seed mass alone may not be an accurate metric of how much energy the seed has received from its parent to grow in a way to help it survive and get established. We believed that seed specific mass (SSM), which is seed mass per unit area, would be a better indicator of the seed's energetic reserves. We measured seed specific mass of three important rangeland restoration bunchgrasses, and found that SSM and early seed root growth were higher in seeds that survived for nearly a year in sterile agar, a growth medium that is essentially nutrient free. We think selecting and developing bunchgrasses that produce seeds with higher SSM may be an important step to take in improving the low success rate in sagebrush steppe restoration efforts.
Technical Abstract: Maternal provisioning to seeds is critical to later plant success, and identifying seed traits that predict successful plant establishment and resilience may facilitate improved plant material selection for rangeland restoration. Although size-standardized measurements are typically recorded for leaf traits, this is not the case for seed traits. In this study, we investigated whether an area-standardized metric, seed-specific mass (SSM), was better associated with seedling performance relative to simple seed mass. We germinated seeds of bluebunch wheatgrass (Pseudoroegneria spicata [Pursh.] A. Löve), crested wheatgrass (Agropyron cristatum L. var. Hycrest II), and Sandberg bluegrass (Poa secunda Presl.) on sterile agar and tracked seed mass, SSM, and subsequent seedling growth and mortality to investigate relationships between seed traits and seedling performance. SSM showed clear variation among species despite similarities in seed mass, and species-specific patterns of mortality most closely tracked variation in SSM. Crested wheatgrass seedlings that survived to 52 wk had significantly greater SSM than those that perished during the study, and surviving seedlings also had significantly longer roots at wk 4 than those that died. Seed mass and SSM each explained variation in seedling traits to some extent. Simple seed mass best predicted variation in early leaf area within species, while root length was best predicted by SSM across species. Our study is indicative that SSM warrants consideration in future studies investigating maternal energetic provisioning and seedling performance.