Nutrient Allocation of ‘TifEagle’ Bermudagrass as Influenced by Trinexapac-Ethyl

ABSTRACT

Inhibiting shoot growth of dwarf bermudagrass [Cynodon dactylon(L.) Pers. × C. transvaalensis Burtt-Davey] with a plant-growth retardant, trinexapac-ethyl (TE), may redirect nutrients and photosynthate away from leaf tissue to promote root growth and improve nutrient-use efficiency. Two greenhouse experiments evaluated three rates of TE, 0.025, 0.05, and 0.075 kg a.i. ha⁻¹, applied every three weeks on ‘TifEagle’ bermudagrass for 12 weeks. Lysimeters constructed to United State Golf Association specifications were arranged in a randomized complete block design with four replications. Increased TE rates quadratically reduced clipping yield 38%–75%, improved turf quality 6%–13%, and enhanced chlorophyll concentrations 30%–70% over the untreated grass. Dry-root mass increased with TE rate 11%–37% after 12 weeks. Total clipping nutrients recovered from five sampling dates were reduced by approximately 50%, 85%, and 90% for turf receiving TE at 0.025, 0.05, and 0.075 kg ha⁻¹ 3 wk⁻¹, respectively. Thatch (stolons and rhizomes) and roots had higher nitrogen (N) concentration and retention with increased TE rate, suggesting inhibited leaf growth increased N storage in belowground plant tissue. Overall, TE may effectively enhance turf quality, root growth, and nutrient-use efficiency of dwarf-type bermudagrasses. Chemical name used: trinexapac-ethyl, [4-(cyclopropyl-[α]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethylester].

Keywords:

• nitrogen
• plant growth regulator

ACKNOWLEDGMENTS

The authors gratefully acknowledge the Syngenta Corp., South Carolina Turf and Landscape Association, and the Clemson Research Initiative Grant for funding this work.

Notes

*Significant at the 0.05 probability level.

^a Total clippings harvested from 12 weekly samples in Study 2.

^b Visual quality was rated 1–9 with 1 equal to dead turf and 9 equal to dark-green turf. Results were pooled from week 4–12.

^c Total chlorophyll concentrations pooled over four samples.

*Significant at the 0.05 probability level.

^a Roots were harvested from the entire lysimeter after 12 weeks.

^b Thatch layer (stolons and rhizomes) was harvested from the entire lysimeter after 12 weeks.

*Significant at the 0.05 probability level.

*Significant at the 0.05 probability level.

^a Nutrient recovery was sampled 2, 5, 8, 11, and 12 weeks after initial trinexapac-ethyl treatments in Study 2.

*Significant at the 0.05 probability level.