Raw sawdust substrates and fertilization in the plant quality of Pinus cooperi Blanco seedlings grown at the nursery

Abstract

In order to ensure the success of reforestation programs, it is necessary to use high quality seedlings. Using alternative substrates of wide availability and low cost (raw pine sawdust and composted pine bark) may be a viable option to produce such seedlings. Therefore, the effect of four substrates (composed of raw pine sawdust, composted pine bark and peat moss) in interaction with two controlled-release fertilizers (Multicote^TM and Osmocote Plus^TM) on the quality of nursery-grown Pinus cooperi seedlings was assessed. The seedlings were planted in polystyrene trays with 77 cavities and a capacity of 170 mL per cavity. The substrates evaluated were: S1) 46 % peat moss + 54 % bark, S2) 30 % peat moss + 20 % bark + 50 % sawdust, S3) 25 % peat moss + 25 % bark + 50 % sawdust, and S4) 20 % peat moss + 30 % bark + 50 % sawdust ―all of them combined with Multicote^TM (18-06-12, N-P-K) and Osmocote Plus^TM (15-09-12, N-P-K). The experimental design utilized was completely randomized, with a 4 × 2 factorial arrangement. In nine-month-old seedlings, the best results for the variables diameter, total biomass and Dickson quality index were found in substrate S1: 46 % peat moss + 54 % bark with 8 g L^-1 of Multicote^TM. However, substrate S2: 30 % peat moss + 20 % bark + 50 % sawdust in combination with 8 g L^-1 of Multicote^TM also yielded acceptable values and, in addition, reduced the production costs by 39.8 %, due to the substrate and fertilizer.