Influence of pot size on early seedling growth of Grevillea robusta and Cupressus lusitanica in Kenya

Pot size is vital for raising of nursery seedlings. Different sizes of pots are needed for various tree species. An experiment was set up to investigate the best pot size for Cupressus lusitanica and Grevillea robusta species. The experiment was laid down as a RCBD with 8 treatments replicated 3 times. Treatments comprised of 4 different pot sizes as follows: large, medium, small and smallest as well as two species. Forest soil mixture was used for potting and 10 pots were used per each treatment per replicate while 7 plants were randomly selected for sampling. The experiment was carried out from September 2017 for a period of 8 months. The variables measured included; shoot, foliage and roots. ANOVA was done using Genstat package while the means were separated at P< 0.001 using LSD. The results showed that large pots had significantly (P<0.001) higher values in height, shoot fresh biomass, total fresh plant biomass and seedling stem volume compared with the other pot sizes. Large pots also showed significantly higher root collar diameter (6.23 mm) compared with the medium pot (4.33 mm). For species, Cypress showed significantly superior height (27.84 cm) and number of leaves (24.52) compared with Grevillea (18.73 and 18.27 cm respectively). In conclusion, shoot fresh biomass and total fresh plant biomass were positively correlated with pot size. This study recommends the use of large pots for raising Grevillea and Cypress seedlings in the nursery since they take 8 months to attain planting size.