Saw palmetto (Serenoa repens), a palm species native to the Southeastern United States, is used in ornamental plantings and landscaping. From Mar. 1998 to Mar. 1999, we conducted an experiment to assess effects of different levels of nitrogen addition on three sizes of containerized saw palmettos in southwest Florida. Palmettos were in 26-L containers (plant height 30 to 50 cm, no above-ground rhizome), 38-L containers (plant height 50 to 80 cm, above-ground, prostrate rhizome), and 170-L containers (three erect above-ground rhizomes 1 to 2 m high). We applied granulated ammonium nitrate (34% N) to the soil surface four times during the year, at 6 yearly rates of N addition for each size category of palmettos (24 palmettos in each size category). We also applied granulated concentrated triple superphosphate (46% P2O5) and potassium chloride (60% K2O) at constant yearly rates for each size category. We measured height and width of plants and length and width of leaves at the beginning and end of the experiment. We quantified leaf N, P and K concentration two days after first fertilizer application, and at the end of the experiment. For 26-L plants, increasing rates of N addition were reflected in higher levels of leaf N concentration two days after the first application. Leaf growth was less, and leaf K concentration at the end of the experiment was lower with increasing rates of N addition. Leaf P concentration at the end of the experiment decreased, and then increased with increasing rates of N addition. Plant growth for 170-L plants decreased and then increased, and leaf P concentration at the end of the experiment decreased with increasing rates of N addition.
A substitute variety for agronomically and medicinally important Serenoa repens (saw palmetto)
