Abstract:
African Teak (Milicia excelsa (Welw.) is a giant deciduous forest tree which belongs to the Moraceae family. Slow and erratic seed germination and the dioecy characterize the species. Vegetative propagation has been proposed to overcome some of the reproductive biology challenges in the species. This study therefore assessed the effect of stem size and planting orientation on vegetative propagation of Milicia excelsa (Welw.) ecotypes in Kenya. The experiment was conducted at the Agroforestry Tree Nursery, Egerton University, Njoro, Kenya. The aim of this study was to investigate the ideal stem cutting method of M. excelsa based on size (length) and planting orientation of stem cuttings. The propagation materials were collected from healthy mother trees from the Coast and Western regions of Kenya. A factorial experiment of two factors (cutting lengths and planting orientations), with 3 levels each, was laid in a Randomized Complete Block Design (RCBD) with nine treatments, replicated 3 times. The cutting lengths were 3, 6 and 9 cm, which were then planted in three positions (horizontal, vertical, and slanting angle). The planting medium was composed of river sand. The polyethene sheet tunnel with 1 m and 1.5 m height and width respectively was established and the nursery containers were covered inside. Data was collected monthly on the number and height of sprouts and the cutting survival at the end of 150 days. Data was then subjected to analysis of variance (ANOVA) using GENSTAT 15th Edition. Separation of means was performed using the SED. The results showed that the cutting length had a significant effect on the number of sprouts, F43.45, df=2, p= 0.001 and height of sprouts produced, F48.25, df=2, p=0.001. The planting orientation had a significant effect (p≤0.05) on the number and height of sprouts produced by cuttings throughout the experiment as well as survival of cuttings at the end of experiment. The ecotype had a significant effect, F6.99, df=1, p=0.012 on the number of sprouts obtained by stem cuttings at 30,120 and 150 days after propagation. The highest percentage of cutting survival obtained was 48.41% from the cuttings of 9 cm length and the least was 31.75% from cuttings of 3 cm length. The ecotype and length interaction, and length and orientation were also significant, F3.31, df=4, p=0.001. It was concluded that vertical and slanting positions should be considered as well as the 9 cm length of the cuttings before planting, and their interaction as well as ecotype and length interaction. Further studies should consider the optimum cutting length, age and position of stem cutting.
