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

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.