Abstract
The ability to grow loblolly pine seedlings in a nursery setting requires proactively managing essential needs. Adequate moisture content is required for germination, IPM programs for managing pathogens and competing weeds, soil & fertilizer amendments for fertility, and Fall stress programs to facilitate greater hardiness ahead of lift and storage. While the parameters of each requirement are important to understand, it is of equal importance to know when to initial respective management actions. Such decisions are driven by how crops are responding to local weather events that facilitate physiological changes in seedlings. Growers have used metrics such as chill hours, cold hardiness, and root growth potential to assess when to initial, modify, and complete seasonal activities. However, those traditional metrics may not be adequate to address abnormal weather events, such as warm interruptions, during critical season activities such as harvest. Climate change is incurring consistently more inconsistent weather which requires a greater understanding of physiological mechanisms and how to develop more rapid response metrics to allow growers to make informed management decisions. In this dissertation I conducted two studies using Pinus taeda L. seedlings in 1) controlled greenhouse and 2) operational nursery settings where seedlings of various families were presented to warming treatments to assess whether seedling metrics were impacted, and if near infrared spectroscopy could provide an alternative modeling solution for those metrics. Results showed that in a controlled greenhouse setting, warm interruptions impacted both cold hardiness and root growth potential highlighting the importance of continued research of understanding physiological responses (e.g., thresholds) to abnormal warming events. Additionally, near infrared spectroscopy modeling was able to demonstrate adequate model performance which would allow growers to have perspective on seedling physiological within days and not weeks. Moving from a controlled greenhouse setting to an operational nursery setting encompassed a significant increase in variation across the ability to facilitate warm interruption treatments, seedling vigor, and range of responses documented across response variables. A consistent trend across both studies was the importance of considering family specific inferences, especially as the continued investment in tree improvement programs will facilitate larger germplasm populations to be grown across nurseries.