Multifactorial optimisation of the nutrient solution for hydroponically grown chicory plants

This research elaborates a methodology for experimenting with the mineral composition of nutrient solution in a multifactorial way using mixture theory. Under an open plastic greenhouse chicory plants were cultivated in hydroponics. To investigate, in a multifactorial way, the influence of the anion composition of the nutrient solution, an experimental design was setup with the independent variables NO3-, H2PO4-, SO42- and Cl-, using a mixture approach. A specific mixture model was fitted to the macromorphological measurements of both the vegetative and the reproductive growth phase. For two response variables (number of leaves and forcing efficiency), the models were used to represent the response surface over the experimental region. The nitrate concentration of the nutrient solution applied during the vegetative growth of the chicory plants was the most important factor in influencing both vegetative and reproductive growth of the chicory plants. A high nitrate concentration in the nutrient solution during the vegetative growth phase resulted in luxuriant vegetative growth, while the reproductive growth was poor (low production of chicory heads of inferior quality). (C) 1998 Elsevier Science B.V. All rights reserved.