QUALITY OF SYNGONIUM PODOPHYLLUM 'SILVER' PLANTS AS RELATED WITH THE NUTRIENT AVAILABILITY IN THE ROOT-ZONE

The purpose of this trial was to study the nutritional status of the root-zone, using the substrate solution obtained with the suction cup method as related to growth and quality of plants of Syngonium podophyllum. For such purpose some sources of fertilizers were tested. The trial was carried out in a type INSOLE greenhouse (Buried Solar Greenhouse), from 19 April to 19 September, 2004. There were four mineral fertilizer treatments: (SLF) a standard liquid feeding, (LFSF) a fertilizer (17-8-14) containing nitrate (NO₃^-), ammonium (NH₄⁺) and a nitrification inhibitor (3,4-dimethylpyrazole phosphate, DMPP) and (CRF) two coated controlled release fertilizers (Basacote Plus (16-8-12) plus half concentration of SLF and Osmocote Plus (16-8-12) plus half concentration of SLF). The nutrient substrate solutions showed important differences, especially when CRF were incorporated to the substrate. Substrate buffers the system, avoiding a high pH lowering. Electrical conductivity was highest in CRF, due to the nitrate concentration, a fact suggesting that the use of controlled release fertilizers should be reconsidered in tropical crops. Basacote treatment showed a good-excellent plant quality; plants treated with LFSF and Osmocote treatments also showed a good quality, while SLF depressed the quality of plants. The efficiency of different ways of fertilization has been studied globally, LFSF being significantly higher.