Defoliation Effects on Persistence and Productivity of Four Pennisetum spp. Genotypes
2002
Macoon, Bisoondat | Sollenberger, Lynn E. | Moore, J. E. (John E.)
‘Mott’ dwarf elephantgrass (Pennisetum purpureum Schum.) is productive and persistent but costly to establish. Interspecific hybrids that are easier to establish have been developed between pearl millet [P. glaucum (L.) R. Br.] and elephantgrass, but questions remain about their persistence. A field experiment was conducted on a hyperthermic, uncoated Aquic Quartzipsamment soil in 1990 and 1991 to determine the effect of defoliation frequency (6 or 12 wk) and stubble height (20 or 40 cm) on dry matter (DM) yield and persistence of Mott and three hybrids (S360, S4, and S41) and to examine the relationships among persistence, number of tillers, and organic reserves. In 1990, total annual yield of Mott ranged from 5.8 to 10.7 Mg ha⁻¹ and was similar to S41 (9.5–11.7 Mg ha⁻¹). Hybrid S4 (6.1–8.7 Mg ha⁻¹) was intermediate, and S360 (4.7–7.4 Mg ha⁻¹) yielded least. Yields were greater for Mott than the hybrids in 1991, regardless of clipping treatment. After 1 yr of defoliation, winter survival of the hybrids was 46 (S41), 21 (S360), and 9% (S4) compared with 100% for Mott. After 2 yr, Mott survival was 100%, but no hybrid plants remained. Total nonstructural carbohydrate concentration of rhizomes was greatest for S360 and with more lenient defoliation, but it was not related to persistence. These data indicate that hybrids are productive in fully established stands, but lack of persistence precludes recommendation for their use in permanent pastures or harvested forage systems based on perennials.
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