2017 ASHS Annual Conference

Abstract

Postharvest needle abscission is a complex physiological process in balsam fir involving many factors, but little is known about the link between soil and tree nutrition and needle loss. Soil, tissue, and branches were collected from 18 balsam fir trees each month from April to November and evaluated for postharvest needle abscission characteristics. Soil samples were evaluated for moisture, pH, organic matter, cation exchange capacity, and various mineral elements. Needle tissue samples were evaluated for mineral elements. Many parameters were found to vary based on month throughout the study, but not all were associated with needle abscission. Soil organic matter, cation exchange capacity, Ca, and Mn all had a significant (P < 0.01) positive relationship with needle retention; soil Al had a significant (P < 0.01) negative relationship with needle retention. Needle NO₃-N, Ca, and Fe were also associated with needle abscission. The strongest positive relationship was found between needle Ca and needle retention (R² > 0.50), suggesting that higher concentrations of tissue Ca were linked to superior needle retention in balsam fir. Overall, this study provides evidence that changes to soil management, such as inclusion of organic matter and adjusting certain mineral elements may provide benefit to postharvest needle retention in balsam fir.