Quantifying Stem Elongation in Oriental and Asi-florum Lilies

Abstract

Our objective was to quantify the stem-elongation patterns of several Oriental and Asi-florum lily cultivars to develop graphical tracking charts where actual crop height can be compared visually against a target growth curve. Oriental lilies (`Mona Lisa' and `Stargazer') were grown in research greenhouses at Michigan State Univ. (MSU) during 1994 and 1995. Asi-florum lily cultivars (`Centurion', `LA-87', `Non-stop', `Salmon Queen', and `Salzburg') were grown at MSU in 1995. Plants received constant 20 °C from emergence to flower in 1995, and constant 15, 18, 21, 24, or 27 °C in 1994. Elongation of Oriental lily plants followed a sigmoid pattern. Oriental lily cultivars elongated rapidly after emergence until 60% of the relative time between dates of emergence and first open flower, at which time plants had achieved ≈82% (`Stargazer') or 85% (`Mona Lisa') of their final height; elongation then exhibited a plateau phase. In contrast to the Oriental lilies, Asi-florum cultivars consistently exhibited a more constant elongation rate throughout the growing period. Simplified graphical tracking curves were developed based on the patterns of elongation and were programmed into a computer decision—support system (`UNH FloraTrack'). The graphical tracking curves were tested by growing `Stargazer', `Mona Lisa', and four Asiflorum cultivars (`Donau', `Dream', `Moneymaker', `Spirit') at the Univ. of New Hampshire and MSU during 1997 to height specifications of 51 to 56 cm (including a pot height of 15 cm). Sumagic growth retardants were applied as a prebulb dip at 5 ppm and as a foliar spray at 3 ppm when plant height was above the target curve. Final height targets were achieved using this method. E-mail prf@hopper.unh.edu; phone, (603) 862-4525.