Yield and quality response of rose geranium (Pelargonium graveolens L.) to sulphur and phosphorus application

Abstract

Sulphur and phosphorus are essential plant macronutrients. Sulphur is involved in the formation of chlorophyll, activation of enzymes and is part of coenzyme A. Phosphorus forms part of the structure of nucleic acids and phospholipids. Two separate studies were conducted to determine the effects of sulphur and phosphorus levels in nutrient solutions on yield and quality of hydroponically grown rose geranium as well as setting standards of sulphur and phosphorus amounts to be used in the production process. The effect of four levels of sulphur (0.36, 1.90, 3.44 and 4.98 mmol l-1) was investigated in the first study and in the second study four levels of phosphorus (0.1, 0.8, 1.5 and 2.2 mmol l-1) were also investigated. All treatments were assigned in a completely randomised block design with five replicates. The results of the first study showed a significant effect of sulphur on the number of branches, plant height and foliar fresh mass. Foliar fresh mass and oil yield peaked at the 3.44 mmol l-1 concentration. The second study showed that plant height and the number of branches was not affected significantly by phosphorus, but foliar mineral phosphorus, magnesium and potassium were affected. Oil yield of rose geranium increased linearly with increased phosphorus concentrations. Both the guaia-69-diene content and the citronellol:geraniol ratio were greater at the highest phosphorus level, which indicated that oil quality can be enhanced by using relatively high phosphorus concentrations in nutrient solutions. Copyright © Combined Congress Continuing Committee.