Sewage sludge assessment on growth of Acacia mangium seedlings by principal components analysis and orthogonal contrasts

This experiment aimed to compare combinations of sewage sludge-based substrates on the growth of Acacia mangium seedlings by principal component analysis (PCA) and orthogonal contrasts (OC). It was conducted in structures of a forest nursery, localized in Southeast of Brazil, in 280 cm³ tubes constituted by 14 treatments and 5 replicates of four plants. When the seedlings reached 100 days after sowing, the treatments containing sewage sludge associated with vermiculite were those that stood out for the growth of A. mangium seedlings, showing the highest averages for the biometric features. The addition of coconut fiber and coffee straw did not produce good growth as well as the evaluated commercial substrate. It can be stated that the use of principal components and OC were efficient in evaluating the best substrate added to the sewage sludge having a limitation in identifying the best ratio between constituents of the substrate.