Effect of controlled release fertilizers versus liquid fertilizers on fruit yield and nutrient dynamics in forcing tomato culture with root-proof capillary wick irrigation.

摘要

The root-proof capillary wick irrigation system eliminates the requirement of irrigation control and water drainage equipment. The application of controlled release fertilizer (CRF) instead of liquid fertilizer (LF) to this system would be economical because it obviates the need for complicated fertilization equipment. In this study, we evaluated the effect of CRF and LF with respect to fruit productivity and nutrient dynamics in forcing tomato culture. The experiment was conducted from October 2008 to June 2009. Plants were supplemented with CRF (16.2 g N per plant) or LF (electric conductivity (EC) value was 1.4 dS m-2) via irrigation water at the beginning of the experiment. Marketable fruit weight was significantly lower with CRF than with LF, especially at the upper trusses, whereas there was no significant difference in the fruit brix. Stem diameter, an indicator of plant growth viability, was greater with CRF than with LF, and the reverse was true for the stem diameters of the middle and upper parts of the plant. Substrate solution EC was lower with CRF than with LF throughout the experimental period. The ion concentrations in the CRF substrate solution, particularly those of NO₃-, PO₄3-, and K+, were maintained at very low levels after the mid-February, suggesting that plants absorbed the nutrients promptly from CRF surfaces. Nutrient absorption per plant as well as per kilogram fruit production was lower with CRF than with LF. These findings indicate that isolated CRF application is suitable for forcing tomato culture, and that nutrients are efficiently utilized for fruit production in plants supplemented with CRF in this system. Fertilizer-combination management of CRF to increase fruit yield during later phases of the plant growth cycle remains to be established.