Effect of potassium and potting-bag size on foliar biomass and related attributes and oil composition of rose geranium (<i>Pelargonium graveolens</i>)

Abstract

This study was conducted to evaluate the effect of four concentrations of potassium (K; 1.3, 3.3, 5.3 and 7.3 mmol L⁻¹) and two potting-bag sizes (5 and 10 L) on foliar biomass and related attributes and oil composition of rose geranium (Pelargonium graveolens). Plants were grown in a climate-controlled greenhouse at the University of the Free State and treatments were arranged in a split plot design. Potassium concentrations were allocated to the main plots and potting-bag size to the subplots replicated three times. Plant height, K tissue content, linalool, geraniol, geranyl formate and citronellol:geraniol ratio were affected by the K application. Plant height, number of branches, branch:height ratio, foliage fresh mass, K tissue content and oil yield were affected by the potting-bag size. Foliar fresh mass was significantly increased by the interaction between K concentration and potting-bag size. Growers may use a 5.3 mmol L⁻¹ K concentration and a 5 L potting bag for optimum production of rose geranium under soil-less cultivation.

Keywords: C:G ratio, enzyme activation, oil quality, potassium, rose geranium