Bermudagrass Putting Green Growth, Color, and Nutrient Partitioning Influenced by Nitrogen and Trinexapac‐Ethyl

Abstract

Plant growth regulators (PGRs) improve turf color by inhibiting leaf growth and may reduce fertilization requirements of bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] golf greens by reducing nutrients removed through clipping collection. To test this hypothesis, growth, color, and nutrient allocation of ‘TifEagle’ bermudagrass maintained at 3.2 mm were investigated in field experiments conducted in Clemson, SC, from April to August in 2003 and 2004. Ammonium nitrate was applied at 6, 12, 18, or 24 kg N ha−1 wk−1 with a PGR, trinexapac‐ethyl {[4‐(cyclopropyl‐[α]‐hydroxymethylene)‐3,5‐dioxo‐cyclohexane carboxylic acid ethyl ester]} (TE), at 0 or 0.05 kg a.i. ha−1 3 wk−1 Turf required 18 to 24 kg N ha−1 wk−1 from May to June and ≤12 kg N ha−1 wk−1 from July to August to maintain acceptable color (≥7, 1–9 scale). Trinexapac‐ethyl initially caused discoloration but bermudagrass recovered and had color enhanced 10 to 25% from nontreated. Trinexapac‐ethyl reduced clippings 67% from nontreated while clippings, percentage of lateral regrowth, and aerification recovery increased with N rate. Bermudagrass treated with TE had similar root mass to nontreated but 5% greater stolon and rhizome mass, 18% higher chlorophyll concentration, up to 67% reduced lateral regrowth, and up to 38% reduced aerification recovery. Trinexapac‐ethyl reduced leaf N, P, K, Mg, S, and Fe concentrations 10 to 25% and increased rhizome concentrations 8 to 36%. Nutrients recovered through clippings were reduced ≈70% from TE applications while TE‐treated turf had increased N, P, K, Ca, Mg, S, Mn, and Fe retention in stolons and rhizomes. Overall, TE enhanced color while reducing nutrient translocation from rhizomes to leaves, thus increasing bermudagrass nutrient retention.