EGGPLANT YIELD IN RESPONSE TO POTASSIUM FERTILIZATION ON SANDY SOIL

'Classic' eggplant (Solanum melongena L.) responses to K fertilization were evaluated in Spring and Fall 1991 at Live Oak, Fla., on soils testing low in Mehlich-1 extractable K. Total season yield leveled off at 5 1.1 t.ha-1 with 94 kg K/ha fertilization in spring and at 53.3 t.ha-1 with 60 kg K/ha in fall. Critical K concentrations (in grams per kilogram) in whole leaves were almost-equal-to 45 at first flowering, 35 at early fruiting, 30 during harvest, and 28 at the end of seven harvests. Fresh petiole-sap K critical concentrations (in milligrams per liter) were almost-equal-to 4500 to 5000 before harvest and 4000 to 4500 during harvest. Less than 3500 mg K/liter in fresh sap indicated K deficiency in fruiting plants. The Mehlich-1 soil extractant procedure predicted similar responses at the two sites; however, yield responses showed that the two sites differed in fertilization requirements. Fertilizer recommendations for K at both sites exceeded eggplant K requirements.