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As bermudagrass (Cynodon dactylon (L.) Pers.) transitions from winter dormancy to active growth in spring, nitrogen is essential for new tissue growth. We examined the relative contributions of internally stored nitrogen and that taken up by preexisting and newly produced roots. Field-collected dormant bermudagrass was transferred to a nutrient solution culture system in a growth chamber. Cultures were provided either a non-nitrogen-containing solution or one amended with nitrate labeled with the 15N isotope of nitrogen, which allowed tracking of endogenous and exogenous N pools in all tissues as growth began. Nitrogen in stolon internodes was the largest N source for early growth. Though mass increased at the same rate in both N treatments over 3 weeks of growth, the unfertilized treatment showed early signs of nitrogen deficiency: low tissue N, slowed leaf elongation, and fewer but longer roots. Preexisting roots were active in absorption almost immediately; new roots were produced quickly and h...