Changes in amounts of total soluble carbohydrates and ascorbic acid were related to needle length of eastern white pine during June and July 1967 at Bent Creek Experimental Forest. Sugar values remained low through the early growing season, and several instances of injury to clones sensitive to tipburn occurred as late as mid-July. Sugar levels fluctuated somewhat, increasing during more regularly as the needles matured, and with less short-term fluctuation than did soluble carohydrates. The relatively low carbohydrate content may have been indicative of a slow maturation of needle tissues, which may be related to a prolonged sensitvity to air pollutants. If so, the amount of soluble carbohydrates or asorbic acid may be more meaningful than needle langth as an indication of needle maturity.
Barnes, Robert L; Berry, Charles R. 1969. Seasonal Changes in Carbohydrates and Ascorbic Acid and White Pine and Possible Relation to Tipburn Sensitivity. Res. Note SE-124. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 4 p.