The effects of freezing and stratification on pecan (Carya illinoinensis) seed germination and seedling growth

Authors: Wang, Xinwang; Kubenka, Keith; Hilton, Angelyn; Chatwin, Warren; Cox, Toni; Tondre, Braden

Submitted to: Technology in Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2024
Publication Date: 1/9/2025
Citation: Wang, X., Kubenka, K.A., Hilton, A.E., Chatwin, W.B., Cox, T.M., Tondre, B.S. 2025. The effects of freezing and stratification on pecan (Carya illinoinensis) seed germination and seedling growth. Technology in Horticulture. 5. Article e002. https://doi.org/10.48130/tihort-0024-0030.
DOI: https://doi.org/10.48130/tihort-0024-0030

Interpretive Summary: Pecan growers typically graft their preferred cultivars onto suitable rootstocks. Choosing the right rootstock is crucial for the tree's health and productivity. Therefore, obtaining healthy and superior rootstock seedlings is the initial step. This study examined how treating pecan seeds with freezing or stratification influenced their ability to sprout and develop into seedlings. We evaluated 12 seed groups from various geographical origins to determine the most effective approach. Our findings revealed that stratification accelerated germination, while freezing had minimal impact. The results also found that the seeds' origins did not significantly affect germination rates, but they did influence how seeds responded to treatments. The resulting seedlings also exhibited varying growth patterns depending on the treatment received. Some grew taller with thicker stems, particularly those from the western and southern regions. In addition, the quality of the nuts did not appear to influence seed germination or seedling growth. Overall, this study provides valuable insights for optimizing pecan tree cultivation. Understanding how different treatments interact with various seeds can enhance the efficiency of pecan tree production.

Technical Abstract: Pecan (Carya illinoinensis) cultivation is crucial for commercial production, requiring appropriate rootstocks that adopt local environments. Historically, pecan breeding has focused on scion enhancement, neglecting rootstock selection due to propagation challenges. However, rootstock greatly influences scion growth, phenology, and productivity. Growers commonly propagate rootstock using open-pollinated seeds, with seedstock selection affecting traits such as germination and stress tolerance. Seed dormancy presents challenges, with some pecan varieties exhibiting traits like thick shells or preferences for stratification, which affect both germination and seedling growth. Cold treatments such as freezing and stratification are common in pecan nurseries, yet their effects are not well understood. This study investigates how freezing and stratification treatments impact seed germination and seedling growth across 12 pecan seedstocks from diverse origins. Results indicate that stratification significantly enhances germination across seedstocks, while seed origin influences treatment responses without significantly altering germination rates. Seedling growth varies depending on treatment combinations, with western and southern seedstocks generally producing taller seedlings. Understanding the interactions between treatment and seeds is crucial for optimizing nursery practices and improving seedling production efficiency, thus contributing to the sustainability of pecan cultivation. This study underscores the importance of seed treatments in pecan cultivation and provides valuable insights for further research to refine nursery practices and ensure successful pecan production.