MULTIFACTORIAL OPTIMIZATION OF THE NUTRIENT SOLUTION FOR HYDROPONICALLY GROWN CHICORY PLANTS

This research elaborates a methodology for experimenting with the mine ral composition of nutrient solution in a multifactorial way using mix ture theory. Under an open plastic greenhouse chicory plants were cult ivated in hydroponics. To investigate, in a multifactorial way, the in fluence of the anion composition of the nutrient solution, an experime ntal design was setup with the independent variables NO3-, H2PO4-, SO4 2- and Cl-, using a mixture approach. A specific mixture model was fit ted to the macromorphological measurements of both the vegetative and the reproductive growth phase. For two response variables (number of l eaves and forcing efficiency), the models were used to represent the r esponse surface over the experimental region. The nitrate concentratio n of the nutrient solution applied during the vegetative growth of the chicory plants was the most important factor in influencing both vege tative and reproductive growth of the chicory plants. A high nitrate c oncentration in the nutrient solution during the vegetative growth pha se resulted in luxuriant vegetative growth, while the reproductive gro wth was poor (low production of chicory heads of inferior quality). (C ) 1998 Elsevier Science B.V. All rights reserved.