Trinexapac-ethyl Effects on Stolon Activity and Node Vitality of ‘Tifway’ Hybrid Bermudagrass

Abstract

The stoloniferous-rhizomatous growth habit of bermudagrass [Cynodon dactylon (L.) Pers.] is a key feature for fast turf establishment and effective recovery from wear and divots. Trinexapac-ethyl (TE) is a plant growth regulator used extensively to reduce the need for mowing. However, vertical growth suppression of vertical growth has the potential to reduce horizontal growth. Furthermore, side effects reported on several physiological functions could affect node ability to generate new plants. In a greenhouse trial, ‘Tifway’ hybrid bermudagrass (C. dactylon × C. transvaalensis Burtt Davy) grown in pots was treated with increasing rates of TE (untreated control, 0.015, 0.075, 0.150, and 0.300 g·m−2). The treatment effects on the number of stolons produced and their linear growth rate, node production, node vitality, and daughter plant characteristics were investigated. The effects of growth inhibition because of TE application on nodes and daughter plants and the relative duration were also assessed. Starting from 2 weeks after treatment (2 WAT), TE application resulted in reductions of stolon length of 24.6% and 52.9% compared with the untreated control, while at 3 and 4 WAT only 0.150 and 0.300 g·m−2 application rates produced significant reductions in stolon length with values of 37.1% and 52.9% at 3 WAT and of 34.1% and 48.3% at 4 WAT, respectively. The number of nodes per stolon was unaffected by treatments. No effect was observed in node vitality but daughter plants showed a postinhibition growth enhancement when nodes were excised at 4 WAT. TE application at the labeled rate did not affect the number of stolons produced by ‘Tifway’ hybrid bermudagrass compared with untreated control, while a reduction in stolon growth rate was recorded only at 2 WAT. Application at higher rates reduced stolon growth rate longer than labeled rate but not stolon production. None of the treatments reduced the number of vital nodes. Application rates higher than labeled rate produced a postinhibition growth enhancement in plants that originated from nodes excised at 4 WAT.