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Agronomy Journal Abstract -

Defoliation Effects on Agronomic Performance of Seeded Pennisetum Hexaploid Hybrids


This article in AJ

  1. Vol. 86 No. 4, p. 695-698
    Received: July 2, 1993

    * Corresponding author(s):
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  1. R. F. Spitaleri,
  2. L. E. Sollenberger ,
  3. S. C. Schank and
  4. C. R. Staples
  1. Dairy Science Dep., Univ. of Florida. Fla., Agric. Exp. Stn. Journal Series no. R-03249



Interspecific Pennisetum hybrids between pearl millet [P. glaucum (L.) R.Br.] and elephantgrass (P. purpureum Schum.) have been developed that are seed propagated, productive, and high in nutritive value, but defoliation effects on hybrid agronomic performance have not been assessed. A field experiment was conducted on an Adamsville soil (hyperthermic, uncoated Aquic Quartzipsamment) in 1991 and 1992 to determine the effect of three clipping treatments (every 6 or 12 wk to 15 cm and every 6 wk to 30 cm) on dry matter (DM) yield, nutritive value, and persistence of 10 seeded hybrids and ‘Mott’ elephantgrass. In the first year of defoliation, Mott and the hybrids had similar yields when harvested at 6-wk intervals (9.7 vs. 9.2 Mg ha−1 yr−1), but hybrids had greater yields than Mott when harvested at 12-wk intervals (17.9 vs. 13.0 Mg ha−1 yr−1). Yields were greater for Mott than hybrids in the second year, regardless of clipping treatment. In 1991, crude protein (CP) concentration was not different when cut every 6 wk (139 g kg−1 DM), but Mott had higher CP than the hybrids when clipped every 12 wk (112 vs. 95 g kg−1). Across clipping treatments in vitro digestible organic matter (IVDOM) was greater for Mott than for the hybrids (638 vs. 602 g kg−1 OM) in 1991. In 1992 there were no differences in CP or IVDOM between Mott and hybrids. After 1 yr of defoliation, winter survival of hybrid plants was 18%, while Mott survival was 100%. Comparison of reserve status of hybrids and Mott showed that hybrids had lower rhizome mass (0.46 vs. 1.1 kg m−2), total nonstructural carbohydrate (TNC) concentration (115 vs. 276 g kg−1 DM),and TNC pool (56 vs. 304 g m−2). These data indicate that seeded hybrids are productive and high in nutritive value. Their potential for use in the U.S. Gulf Coast, however, depends on development of lines that are more persistent under defoliation.

Research sponsored in part by the Florida Dairy Checkoff Program and by USDA Special Grant 89-34135-4576 administered by the Caribbean Basin Advisory Group.

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