The 2012 ASHS Annual Conference

Adenium obesum, commonly known as Desert Rose, are beautiful flowering tropical plants. Worldwide interest by breeders and hobbyists has led to the development of numerous new cultivars with striking floral displays atop enlarged sculptural caudices; however, cultural guidelines based on scientific research using clonal materials have not been published. In this study, 96 uniform rooted cuttings of the Adenium obesum cultivar Red were grown in 6- and 8-inch pots, each with four different fertilizer rates using Nutricote Plus (18N–6P–K; Chisso-Asahi Fertilizer Co., LTD Tokyo, Japan). Plants were grown 20 weeks (July to December 2011) under natural photoperiod and a temperature range of 18 °C to 35 °C in a greenhouse covered with double polyethylene film which provided a maximum light level of 6000 µmol·m^-2·s^-1.  Plants produced in the larger pots had significantly greater shoot and root fresh weights than those grown in smaller pots at the equivalent nutrition level. Total flower number, based on weekly counts of open flowers, increased linearly in both 6 and 8 inch pots as fertilizer level increased. Final open flower totals at the two highest fertilizer rates more than doubled than those at lowest fertilizer rate in both pot sizes. Best overall plant quality was observed at the 7.5 g/pot rate for 6-inch and at the 12 g and 18 g/pot rates for 8-inch pots. Stem caliper increased significantly in a linear manner with increased fertilizer levels for 6 inch pots. Canopy height and canopy width also increased linearly. For 8-inch pots, canopy width and stem caliper increased linearly at higher fertilizer rates but canopy height showed no significant difference.