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Fig. 1. Time course of seedling nitrate uptake of six Kentucky bluegrass cultivars: BL, Blacksburg; BZ, Barzan; CN, Conni; DN, Dawn; EC, Eclipse; GM, Gnome. Thirty days after seeding, six seedlings of uniform size from each cultivar were placed individually in polystyrene cups filled with 2 mL of a nutrient solution containing 0.6 mM nitrate, and the rate of nitrate uptake was monitored at 24-h intervals. On Days 5 and 19, deionized water was provided (indicated by "–NO3–") in place of the nitrate solution. Immediately before the start of nitrate uptake on Days 9 and 22, one-third of the leaf blade lengths were clipped off of each seedling (indicated by "1st cut" and "2nd cut"). On Day 10, no nitrate uptake but nitrate efflux from the roots was detected (indicated by "Efflux").
