EFFECT OF CONCENTRATION OF NUTRIENT SOLUTION ON THE GROWTH AND YIELD OF ROSES DURING THE JUVENILE PERIOD AND MORE THAN ONE YEAR AFTER TRANSPLANTING USING COIR SUBSTRATE IN HYDROPONICS

This study was carried out to investigate the effect of concentration of nutrient solution on the growth and yield of roses during the juvenile period and more than 1 year after transplanting using coir substrate in open soilless culture. Concentration of nutrient solution was four different EC levels (0.6, 1.0, 1.4, and 1.8 dS•m-1). Until 22 days after transplanting, even high concentration of nutrient solution supplied to the substrate, there was no difference in EC of the extracts. After that, they were sharply increased with higher concentration of nutrient solution. Number of shoots were increased with increasing nutrient concentration, but there was no significant difference among treatment except EC 0.6 dS•m^-1 since 3^rd growth cycle.
Long-term cultivation of roses for more than a year using coir substrate, EC and inorganic ions in extracts of substrate was slightly higher in EC 0.6 and 1.0 dS m^-1, and was severely higher above EC 1.4 dS•m^-1. In high temperature period, yield was decreased with increasing of nutrient concentration. In low temperature period, The highest yield was obtained from EC 1.0 dS•m^-1 and yield was decreased in EC 1.8 dS•m^-1 compared to the other treatments. Judging by results of growth and contents of inorganic ion in extracts of substrate, our experiment suggests that the suitable nutrient concentration is EC 1.8 dS•m^-1 until 90 days and then EC 1.4 dS•m^-1 until 165 days after transplanting that is more higher than conventional nutrient concentration. Long-term cultivation of roses for more than a year, suitable nutrient concentration was EC 0.6~ 1.0 dS•m^-1.