Asian Journal of Research in Agriculture and Forestry

Weeding for young tree seedlings is critical for their growth. Weeds offer stiff competition for water, nutrients, light and space with the companion crops. Most tree nurseries do not have a formal weeding interval, hence the need for the current research. A nursery experiment was set up to investigate the best weeding interval for Grevillea robusta seedlings for a period of 8 months in Njoro, Kenya. The experiment was laid down in a RCBD with 4 treatments replicated 3 times. The treatments were as follows: Continuous weeding, 1-month weeding interval, 2-months weeding interval and non-weeding. Data was analyzed using ANOVA while LSD was applied to separate the significantly different treatments at P<.05. Results showed that survival for non-weeding (83.33%) was significantly lower (P =.04) compared with 1-month and 2-months weeding interval (100.00 and 96.67%) respectively. Continuous weeding and 1-month weeding interval showed significantly higher height (23.00 and 25.27cm) respectively compared with 2-months weeding interval and non-weeding (17.67 and 13.83cm) respectively. On the other hand, 1-month weeding interval showed the highest root length (22.67cm) which was significantly different (P=.05) compared with non-weeding (15.67cm). Root biomass was significantly higher (P=.02) for 1-month weeding interval (4.67g) compared with non-weeding (2.50g). Grevillea robusta seedlings should be weeded at an interval of one month during the nursery period in order to attain favorable growth. Non-weeding compromises the seedling growth due to severe competition from weeds. Even though continuous weeding favors seedling growth, it is not economical due to high labor demand. Further research should be conducted using different soil mixtures and other species.