Effect of Plant Density on Morphological Characteristics, Yield and Chemical Composition of Napier Grass (Pennisetum purpureum (L.) Schumach)
AbstractAn experiment to assess the effect of plant density on morphological characteristics, dry matter production and chemical composition of Napier grass (Pennisetum purpureum (L.) Schumach) was conducted in 2004 and 2005 at Haramaya University, eastern Ethiopia. There were a total of nine treatments with 1.5, 1 and 0.5m spacing between rows and 0.75, 0.5 and 0.25m spacing between plants, which consisted of 8,888.9, 13,333.3, 26,667.7, 13,333.3, 20,000, 40,000, 26,667.7, 40,000, and 80,000 plants per ha, arranged in a randomized complete block design with three replications. The plot size was 3m width x 6m length and the spacings between replications and plots were 1.5m and 1m respectively. There was no significant (P > 0.05) effect in morphological characteristics of Napier grass due to plant density during the establishment year. However, the number of tillers, total leaves, internode number, internode length, basal circumference and leaf length per plant were significantly (P < 0.05) affected by plant density in the second year. There was a significant (P < 0.05) difference in dry matter (DM) yield due to plant density. A considerable variation in DM yield between the two years and number of harvests in each year was observed during the study and the DM yield in 2005 was much greater than the 2004 crop season. Higher DM yields were obtained from 80,000 (7.80 t/ha) and 40, 000 (39.9 t/ha) plant density in 2004 and 2005 respectively. There was no significant (P > 0.05) effect on the chemical composition of Napier grass due to plant density. However, the crude protein (CP) content of all the treatments was above 15%, which is the optimum required for animal growth or production. The fibre fractions were also below the threshold level (600 g/kg DM) at which DM intake of cattle is affected. Based on DM yield production and CP content, the production of Napier grass using 40, 000 plants per hectare is recommended to livestock producers in eastern Ethiopia agro-ecologies of the country.
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