131 Effect of Blended Composts and N Rates on Growth Performance of Potted Poinsettia

Abstract

Growth performance of potted `Peterstar Pink', `Top White', `Red Sails', and `Red Success' were evaluated in eight substrates and three fertilization rates. The substrates included Sunshine Mix 1 and Pro Gro 300S as control, and compost blends at 33%, 50%, and 67% of final substrate volumes mixed with peat and perlite (1:1). The blends included 2:1, 1:1, or 1:2 ratio of polymer dewatered biosolids (PDB):poultry litter (PL) and PDB: yard wastes (YW). Fertilization was applied twice weekly at 75, 100, and 150 mg/L N from 19N--2.2P-16.6K. Plants grown in Sunshine Mix 1 performed better than those grown in Pro Gro 300S. The growth parameters measured improved as the N rates increased for both controls. Plant diameter, grade, and dry weight of plants grown in 150 mg/L N treatment were usually similar to those in 100 mg/L N and were not 11% more than those at the lowest N treatment. The 1 PDB: 1 PL blend at the high N treatment produced premium-quality plants, and all remaining PDB:PL treatments produced good quality plants. The PDB:YW blends that received 100 and 150 mg/L N produced premium quality plants. The PDB:YW blends at the low N treatment produced slightly better quality plants than those grown in PDB:PL at the 75 mg/L N and were similar in quality as those grown in Sunshine Mix 1 at the 150 mg/L N treatment.