Application of Controlled-release Fertilizer to Forcing Culture of Tomato Using Root-proof Capillary Wick

Abstract

Root-proof capillary wick culture is expected to eliminate water drainage. Application of controlled release fertilizer instead of liquid fertilizer may be economical because liquid fertilizer equipment would not be required. In this experiment, large-fruited tomato was grown at three fertilizer levels; 11.3 gN (LF), 16.2 gN (MF), 21.0 gN (HF) per plant to evaluate a suitable level of controlled-release fertilizer needed for the culture of 15 trusses between October and July. For HF, the experiment was terminated at the end of December due to severe wilting. There was no significant difference in marketable fruits weight between LF and MF, but the soluble sugar content was higher in MF. The stem diameter at the end of experiment was larger in MF. The amount of nutrient remaining in the substrate was lower for N, P₂O₅ and K₂O, but greater for CaO and MgO at each fertilizer level. Each nutrient concentration in the substrate solution was low after the middle of February for both LF and MF. Therefore, enrichment of nutrients in the substrate solution did not occur in either LF or MF. In conclusion, the amount of 16.2 gN per plant may have been sufficient for 15 trusses of tomatoes undergoing forcing culture.