Forage Yield and Nutritive Value of Elephantgrass as Affected by Harvest Frequency and Genotype
Elephantgrass (Pennisetum purpureum Schum.) is known throughout much of the wet tropics for its prolific growth and usage as a forage for ruminants. In a 3-yr study conducted on a welldrained, infertile soil (loamy, siliceous, hyperthermic, Grossarenic Paleudult) and under subtropical conditions near Gainesville, FL, the response of this forage to three harvest frequency regimes was measured. Genotypes evaluated were four tall elephantgrasses (PI 300086, ‘Merkeron’, N-43, and N-51), a dwarf elephantgrass (Mott), and a semi-dwarf Pennisetum glaucum (L.) R. Br. × P. purpureum Schum. hybrid (Selection 3). Forage dry matter (DM) yields for Merkeron, N-43, and N-51 did not differ. For these three genotypes, 3-yr mean DM yields (1986-1988) were 24.3, 21.1, and 17.0 Mg ha−1 yr−1 for one, two, and three harvests per year, respectively. Two-year mean (1986-1987) crude protein (CP) concentrations for all four tall genotypes were 40.3, 57.5, and 75.7 g kg−1 DM while in vitro digestible organic matter (IVDOM) concentrations were 399, 492, and 555 g kg−1 organic matter (OM) for one, two, and three harvests per year, respectively. For Mott, 3-yr mean DM yields were 11.8,11.8, and 11.7 Mg ha−1 yr−1 for one, two, and three harvests per year, respectively. Two-year mean CP concentrations were 52.7, 69.4, and 85.6 g kg−1 DM whereas IVDOM concentrations were 396, 549, and 580 g kg-1 OM, respectively. Merkeron, N-43, N-51, and Mott persisted well. In PI 300086 plots harvested multiple times, major stand losses occurred over the 1987–1988 winter. Selection 3 did not persist. Adapted elephantgrass genotypes can persist in colder regions of the subtropics and should provide substantial quantities of forage.
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