Optimasi Konsentrasi Larutan Hara pada Budidaya Selada (Lactuca Sativa l. var. grand rapid) dengan Teknologi Hidroponik Sistem Terapung

ABSTRACT The objective of this research was determined the optimum nutrient solution concentration on lettuce growth and yield in Deep Pool Growing System (THST). The study was conducted from November 2005 to March 2006 at Deep Pool Growing System facilities, Danasworo Hydrogarden Ciapus, Bogor (S 6 o 38’.19.78”, E 106 o 45’44.52”).  The study was arranged in Completely Randomized Design with four levels of nutrient solution concentration. These are control (without nutrient), EC 0.75 mS.cm -1 , EC 1.50 mS.cm -1 and EC 2.25 mS.cm -1 . The composition of AB Mix nutrient solution were as followed (ppm): NH 4 + 22.5, K + 429, Ca 2+ 180, Mg 2+ 24, NO 3 - 1178, SO 4 2- 108, H 2 PO 4 - 194, Fe 3+ 2.232, Mn 3+ 0.275, Zn 2+ 0.261, B 3+ 0.324, Cu 2+ 0.049 dan Mo 2+ 0.048. Lettuce growth and yield was quadratically increased with nutrient solution concentrations application from 0 to 2.25 mS.cm -1 . Base on total plant weight and marketable plant weight, recommendation range of optimum nutrient solution concentration for lettuce hydroponic production  in THST was between 1.09-1.15 mS.cm -1 .