Growth dynamics of tree nursery seedlings: The case of oil palm

Tree seedling survival in the field partly depends on management during seedling production. Insight into how nursery practices affect seedling growth dynamics would generate understanding in how to optimise tree seedling production. The objective of this study was to analyse the growth dynamics of oil palm seedlings to evaluate the effects of bag size, substrate type, and fertiliser supply, and their interactions. An experiment was run in 2011 (March to November 2011) and repeated in 2012 (April to October 2012) using three bag sizes, four substrates, and three levels of fertiliser supply (3 × 4 × 3 factorial design). Seedling height, collar diameter and number of leaves were measured over time. Seedling growth was analysed by comparing treatment effects at monthly intervals. Data were also fitted to growth curves to analyse treatment effects on absolute and relative rates of increase in seedling height, collar diameter and number of leaves. While substrate and fertiliser supply effects were fairly constant over time, bag size effects increased with larger variance explained over time. We observed that bag size effects overtook substrate, fertiliser and interaction effects from about two months onwards. Seedling height and collar diameter followed an exponential growth while number of leaves increased linearly over time. Analysis of generated data with the different growth models indicated that seedling growth rates were mainly under the influence of bag size, followed by substrate. Interactions between nursery practices, although significant sometimes, did not account for a large part of experimental error. Implications for tree seedling management are further discussed