Response of cocoa (Theobroma cacao L.) seedlings to multi-nutrient fertilizer application in soilless growing media

Lack of well-defined fertilizer recommendation for growing cocoa (Theobroma cacao L.) seedlings in the nursery in soilless growth media affects their vigor, resulting in poor growth and increased mortalities. This study was conducted to evaluate the response of cocoa seedlings to the combined application of NPK and/or micro/secondary nutrients in a soilless medium. The study was a cross-factorial experiment with two factors, NPK and micro/secondary nutrients, arranged in completely randomized design with three replications. There were three levels of NPK (0, 5, and 10 g/L of water) and four types of micro/secondary nutrients (control, Fe, Mg, and Mg + Fe). The combined application of NPK and micro/secondary nutrients significantly increased plant height and chlorophyll content of cocoa seedlings at 30, 60, and 90 days after application (DAA). The treatments also increased dry biomass at 60 and 90 DAA and leaf number and stem girth at only 90 DAA. The combination of either the 5 or 10 g/L NPK and Mg + Fe performed better than the combination of 5 or 10 g/L NPK with Mg or Fe alone and control. The effects of 5 g/L NPK with Mg + Fe and 10 g/L NPK with Mg + Fe on growth and biomass of cocoa seedlings were similar. Either 5 g/L with Mg + Fe or 10 g/L NPK with Mg + Fe can be used to increase growth and biomass of cocoa seedlings. This can contribute toward increased cocoa seedlings vigor at the nursery.