First attempt to force Gladiolus and Liatris in a floating system

Autumn crops of Gladiolus and Liatris were grown under a plastic greenhouse to compare a floating system technique (FST) with a control (C) represented by a traditional growing management (soil and solid fertilizers). The work was aimed at evaluating if FST is suitable for these crops and at studying the cut flower production response to various nutrient solutions, which were: only water (W), calcium nitrate (CN) (5 mol m-3), full-strength Hoagland (FH) and half-strength Hoagland (HH). On Liatris, aeration and no-aeration of solutions were also tested. Periodically, during the growing season, the observations regarded: plant height, leaf chlorophyll concentration (SPAD values), date of flowering. At harvest, the qualitative traits of each spike were evaluated (whole stem and inflorescence length, floret number and visual score). Moreover, the fresh and dry weight and the total N content of plants were measured, as well as the composition of waste nutrient solutions. Crop response to FST varied with species. The Gladiolus performed better when grown on soil with a traditional production system (C), giving longer spikes than FST. FST proved to be suitable for Liatris cultivation and both Hoagland solutions gave taller stems, longer inflorescences and higher quality score, than the control (C). Plain water or calcium nitrate solution appeared to be not suitable for these species. Liatris plants behaved similarly in aerated and no-aerated solutions. In both species, the highest N plant content was observed in both Hoagland solutions, but waste HH solution showed a considerably lower concentration of nutrients.