Abstract
Effect of the planting density on the growth and main stem yield in kenaf (Hibiscus cannabinusL.) was investigated at the Agriculture and Forestry Center, University of Tsukuba, in 2003 and 2004. Kenaf (cv.: KB2) plants were grown at three plant densities: namely, high density (HD), 44.4 plants m-2 (15cm×15 cm spacing) ; middle density (MD), 22.2 plants m-2 (30cm×15cm) ; and low density (LD), 11.1 plants m-2 (30cm×30cm) . The experiment was laid out in a latin square design with three replications. The field was fertilized with 12g m-2, 6g m-2and 3g m-2of N, P2O5, K2O for HD, MD and LD, respectively. Seeds were sown late in May. Ten to 15 plants were sampled twice (141 days after sowing (DAS) and 168 DAS in 2003, 152-154 DAS and 188-191 DAS in 2004) for the measurement of the fresh and dry weights.
As a result, the value of the plant height and number of nodes were higher in the HD plants than in the LD plants during the former cultivation period. However, during the latter period, plant height in the LD plants had caught up with that in the HD plants and increased compared with the height of the HD. The HD plants showed a higher bast yield per unit area, whereas the LD plants showed a higher bast yield per plant. Stem diameter was so large that mechanical harvesting was possible for the HD plants. In conclusion, a planting density of 44.4 plants m-2was found to be adequate for high bast yield and mechanical shoot harvesting in kenaf cultivation.
