Ray, Dustin M. , Bobich, Edward , Ewers, Frank W. .
Seasonal Changes in Non-Structural Carbohydrates in Stems and Lignotubers of Burned and Unburned Southern California Black Walnut (Juglans californica).
Seasonal allocation of non-structural carbohydrates in relation to phenology was investigated for stems and lignotubers of unburned adult and burned, resprouting Juglans californica over a one year period. It was hypothesized that nonstructural carbohydrates in the stems of resprouts would be greater than those of adults throughout the most of the year to support stem elongation, whereas resprout lignotuber stores would be lower than that of adults due to reallocation for stem growth. Nonstructural carbohydrate concentrations in both organs for each season were determined spectrophotometrically via assays and microscopically by determining the relative presence of amyloplasts. Stem growth and leaf, flower, and fruit production and senescence were also determined seasonally. For both burned and unburned trees, non-structural carbohydrate concentrations in stems were maximal during the winter, when the trees were leafless, and lowest during the summer, when new leaf production had slowed. Amyloplasts in stems occurred primarily in radial and tangential rays in the wood and secondary phloem, but also paratrachially with most storage occurring in the outer portions of the secondary xylem. In lignotubers, amyloplasts occurred in multiseriate rays that appeared throughout the tissue. Total non-structural carbohydrates in resprout stems were greater than in adults suggesting reallocation of carbohydrates for stem growth. Starch concentrations in lignotubers and stems were higher in adults in late spring, but greater in resprouts throughout summer, fall and winter. The higher allocation of starch to stems of resprouts was expected, as having storing starch closer to where it is going to be utilized to facilitate shoot growth is more energy efficient than storing it in belowground lignotubers.
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1 - California State Polytechnic University, Pomona, Biological Sciences, 3801 West Temple Avenue, Pomona, California, 91768, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 551B/Convention Center
Date: Monday, August 2nd, 2010
Time: 4:00 PM