In a greenhouse experiment, the effect of the addition of higher levels of potassium (K) in the replenishment stock used to supply nutrients in a nutrient film technique system was examined. For this study, `TU-82-155' sweetpotato was grown hydroponically for 120 days under four nutrient application/replenishment treatments: 1) REG—solution was changed at 14-day intervals and volume allowed to fluctuate; 2) MHH—replenishment with 10× concentrate of a modified half Hoagland solution (MHH) or with water to regain set volume (30.4 liters) and maintain set point of electrical conductivity (EC, 1050–1500 μmho); 3) MHH + 2K—daily replenishment with 10× concentrate of a modified half Hoagland solution (MHH) or with water to regain the set volume and adjust EC to 1400 followed by application of 50 ml of a 2K stock solution to an EC of 1500; 4) MHH/2K—replenishment with 10× concentrate of a modified half Hoagland solution that incorporated the 2K component or with water to regain set volume (30.4 liters) and maintain set point of electrical conductivity (EC, 105–1500 μmho). The storage root yield (g fresh weight per plant) was significantly higher when the 2K treatment was incorporated with the 10× MHH stock. The storage root yield averaged 324.8 g/plant compared with a yield of 289.6 and 252.9 g/plant, respectively, for the REG and MHH nutrient application protocol. As in earlier experiments, the MHH treatment was comparable to the REG protocol, validating the use of a replenishment approach for nutrient supply in hydroponic sweetpotato culture.
Audrey A. Trotman, P. David, D. Mortley, and J. Seminara
P.P. David, A.A. Trotman, D.G. Mortley, D. Douglas, and J. Seminara
A study was initiated in the greenhouse to examine the effects of five