THE RESPONSE OF ROSE GERANIUM (PELARGONIUM GRAVEOLENS L.) TO NITRATE AND AMMONIUM APPLICATION
The potential to produce good quality rose geranium oil using a hydroponic production system was investigated at the University of the Free State. Four levels of nitrate (8, 10, 12 and 14 meq L-1) and four levels of ammonium (0.00, 0.50, 1.00 and 1.50 meq L-1) were evaluated in two separate trials, using a completely randomized block design with five replications. The results obtained showed a significant effect of nitrate on plant height, number of branches, foliar dry mass, chlorophyll content and oil yield. The height of rose geranium obtained at 8 and 10 meq L-1 nitrate concentrations were 46 and 57 cm, respectively. The number of branches was significantly increased by nitrate application and 57 branches were produced at 10 meq L-1 compared to the 47 branches produced at 8 meq L-1 nitrate concentration. The best foliar dry mass of 10 t ha-1 was also produced at the nitrate concentrations of 10 meq L-1 compared to the 4 t ha-1 produced at 8 meq L-1. However, chlorophyll content at 12 meq L-1 nitrate concentration was significantly higher than that obtained at 8 meq L-1. The greatest oil yield (145 kg ha-1) was found at 10 meq L-1 although the citronellol:geraniol ratio was slightly higher than the upper limit required for good oil quality. However, the geraniol and citronellyl formate contents were within the range for top oil quality. Plant height, foliar dry mass, oil yield and chlorophyll content were not significantly affected by ammonium concentrations, but the content of sulphate and nitrogen increased linearly with increasing ammonium concentration.
Sedibe, M.M. and Allemann, J. (2013). THE RESPONSE OF ROSE GERANIUM (PELARGONIUM GRAVEOLENS L.) TO NITRATE AND AMMONIUM APPLICATION . Acta Hortic. 1007, 311-322
essential oil quality, hydroponics, nitrogen, plant growth