Physiology of postharvest needle abscission in balsam fir: water quality modulates postharvest needle abscission

Postharvest needle abscission is a significant problem for the Christmas tree industry and can be promoted by the interaction of genetic, environmental, pre- and postharvest management factors. Relative water content, xylem pressure potential and conductance all decline postharvest, coinciding with needle abscission. Water quality was speculated to link to several of the aforementioned factors Our objectives were to: (1) determine if low quality water supply would accelerate needle abscission, (2) determine if physical methods to improve water quality would delay abscission, and (3) describe the relationships between water uptake, bacterial growth, and needle abscission over time. Reuse of a low quality water supply was found to significantly accelerate needle abscission while frequently replacing branch water supply with fresh water was found to delay abscission compared to controls. Further, bacterial counts increased exponentially in Christmas tree water supply and corresponded with increased abscission. It is concluded that poor water quality contributes to postharvest needle abscission.