Defoliation Effects on ‘Mott’ Elephantgrass Productivity and Leaf Percentage
- C. J. Chaparro,
- Lynn E. Sollenberger and
- C. S. Jones
‘Mott’ elephantgrass (Pennisetum purpureum Schum.) is a high-quality pasture grass for the tropics and subtropics, but information is needed on growth responses of Mott to clipping management. In 1989, 1990, and 1991, a study was conducted on a hyperthermic, uncoated Aquic Quart-zipsamment soil to measure Mott herbage dry matter (DM) harvested and plant-part percentage (1989 and 1990 only) responses to clipping. The study included all 16 treatment combinations of four defoliation heights (10-, 22-, 34-, and 46-cm stubble) and four defoliation frequencies (3, 6, 9, and 12 wk). Treatments were replicated three times in a randomized block design. Data were analyzed by fitting multiple regression equations starting with a second-order polynomial model. In 1989, total DM harvested ranged from 8.0 to 16.2 Mg ha−1 and increased (decreasing rate) as defoliation height was lowered and increased linearly as weeks between harvests increased from 3 to 12. The range of total DM harvested was 4.2 to 11.6 Mg ha-~ in 1990 and 2.6 to 16.1 Mg ha−1 in 1991. Dry matter harvested in 1990 and 1991 increased (decreasing rate) as defoliation height was lowered from 46 to 10 cm and as interval between defoliations increased. Lowest total DM harvested in the third year was observed using a 3-wk defoliation frequency, 10-cm defoliation height treatment, a result of reduced plant vigor. Greatest total DM harvested in all years occurred using a 12-wk frequency, 10-cm height treatment. Across all treatments, live lamina percentage in total DM harvested ranged from 63 to 100% and was greatest for the 3-wk frequency, 46-cm height treatment. Live lamina DM harvested was not affected by treatment in 1989, but in 1990 maximum values were estimated to occur when frequency was 9 to 10 wk and stubble height was 15 to 20 cm. We conclude that Mott elephantgrass is productive and maintains a high leaf lamina percentage over a relatively wide range of defoliation treatments, but close, frequent clipping reduces total DM harvested.
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