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This article in CS

  1. Vol. 51 No. 4, p. 1716-1726
     
    Received: Sept 10, 2010
    Published: July, 2011


    * Corresponding author(s): aldermap@ufl.edu
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doi:10.2135/cropsci2010.09.0515

Regrowth Dynamics of ‘Tifton 85’ Bermudagrass as Affected by Nitrogen Fertilization

  1. PD. Alderman *,
  2. KJ. Boote and
  3. LE. Sollenberger
  1. Dep. of Agronomy, Univ. of Florida, P.O. Box 110500, Gainesville, FL 32611-0500. This research was supported in part by the USDA, Tropical Subtropical Agricultural Research Program

Abstract

‘Tifton 85’ bermudagrass (Cynodon spp.) has been widely adopted as a forage and hay crop and is being considered as a cellulosic ethanol feedstock. The objective of this study was to evaluate the effects of N fertilization rate on Tifton 85 regrowth dynamics. A field study was conducted near Gainesville, FL, on established Tifton 85 in 2006 and 2007. The treatments were N rates of 0, 45, 90, and 135 kg N ha−1 regrowth period−1. Tissue mass, leaf:stem ratio, and tiller number and mass were measured weekly during 28-d regrowth periods. Leaf mass followed logistic time trends with the upper asymptote varying between 50 and 225 g m−2 depending on N rate and season (summer and autumn). Stem mass lagged behind leaf mass for 7 to 14 d, subsequently following linear or quadratic time trends to reach between 75 and 300 g m−2 by 28 d. Increasing N rate from 0 to 135 kg ha−1 period−1 increased tiller mass at 28 d from 1.5 to 3 g tiller−1 in summer and 1 to 1.5 g tiller−1 in autumn. Leaf:stem ratio increased to 1.0 within 14 to 21 d, followed by a subsequent decrease. Rhizome and root mass were not affected by N fertilization. Increasing N rate primarily affected mass and proportion of above-ground plant parts, with little effect on mass of below-ground parts. Nitrogen nutrition index values were similar whether calculated from samples taken to a 10-cm stubble height or from samples taken to the soil surface. Regrowth was not enhanced by N rate beyond 90 kg N ha−1 regrowth period−1.

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