Fine Root Carbohydrate Dynamics of Loblolly Pine Seedlings Grown Under Contrasting Levels of Soil Moisture
Abstract:Fine root growth, mortality, and carbohydrate concentration were compared for North Carolina and Oklahoma-Arkansas families of loblolly pine (Pinus taeda L.) seedlings under well-watered and drought conditions. The objective was to determine if moisture stress affected fine root carbohydrate dynamics and fine root longevity. Seedlings under drought produced new roots with the same starch concentration as well-watered seedlings, despite a 50% reduction in whole-plant growth. The starch concentration in fine roots of seedlings grown under periodic drought did not increase with age; in contrast, the starch concentration in fine roots of well-watered seedlings continued to increase for at least 70 days. There was no evidence that moisture stress accelerated fine root starch depletion. Fine root starch concentration was around 20% less and sugar concentration nearly 13% greater under periodic drought than under well-watered conditions. Fine root starch concentration never dropped below 4%. Fine root mortality was negligible and showed no effect of treatment or seed source. The results of this study do not support the hypothesis that drought accelerates carbohydrate depletion and thereby increases fine root mortality. Plants from the Oklahoma-Arkansas families contained higher starch concentrations in roots and shoots than plants from North Carolina families but produced slightly less biomass. For. Sci. 37(3):766-780.
Document Type: Journal Article
Affiliations: Research Associate, Texas Agricultural Exp. Sta., Rt. 3, Box 2973, Nacogdoches, TX 75961
Publication date: August 1, 1991
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