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Growth of Subtropical Forage Grasses under Extended Photoperiod during Short-Daylength Months


This article in CS

  1. Vol. 43 No. 2, p. 618-623
    Received: Apr 17, 2002

    * Corresponding author(s): trsincl@mail.ifas.ufl.edu
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  1. Thomas R. Sinclair *a,
  2. Jeffery D. Rayb,
  3. Paul Mislevyc and
  4. L. Monica Premazzia
  1. a USDA-ARS, University of Florida, PO Box 110965, Gainesville, FL 32611-0965 USA
    b USDA-ARS, Crop Genetics and Production, P.O. Box 345, Stoneville, MS 38776 USA
    c University of Florida, IFAS, Range Cattle Research and Education Center, 3401 Experiment Station, Ona, FL 33865-9706 USA


One constraint on cattle production in the southeastern USA is the low productivity of perennial forage grasses during the short-daylength months. Evidence indicates that total growth during these months could be enhanced by exposing these grasses to extended photoperiod. A detailed analysis of their year-round productivity and nutritive value is needed to understand fully the consequences of overcoming the photoperiod-induced decline in growth. A 2-yr experiment was established at Ona, FL, in which photoperiod was extended to 15 h throughout the short-daylength months. Four grasses were studied: ‘Pensacola’ bahiagrass, Paspalum notatum Flugge var. Saurde Parodi; ‘Tifton 85’ bermudagrass, Cynodon spp. L. Pers.; ‘Florakirk’ bermudagrass; and ‘Florona’ stargrass, Cynodon nlemfuensis Vanderyst var. nlemfuensis Growth increases were observed in all grasses during the short-daylength months as a result of the extended-photoperiod treatment, with increases in the January through March harvests of 3-fold or more for Pensacola bahiagrass and 1.5- to 2.5-fold for Tifton 85 bermudagrass. Generally, there was no evidence of adverse consequences from sustained growth during the short-daylength months either in the subsequent spring and summer growth or in traits measured in below-ground tissue. With one exception, there was no major influence of the sustained growth on forage nutritive value during the short-daylength months for any of the year-round harvests. Pensacola bahiagrass had decreased crude protein under the extended-photoperiod treatment relative to the natural-daylength treatment. Overall, these results indicated that the selection and genetic incorporation of photoperiod insensitivity into these grasses could enhance productivity without adverse consequences.

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Copyright © 2003. Crop Science Society of AmericaPublished in Crop Sci.43:618–623.