Mineral Nutrition of Cymbopogon nardus (L) Rendle: Part II. Effects of Magnesium and Phosphorus Nutrition on the Fractional Composition of Essential Oil

Results obtained from a fertilizer experiment conducted with thirteen treatments indicate the positive effect of phosphorus and magnesium nutrition on the yield and the fractional composition of essential oil of Cymbopogon nardus. Phosphorus nutrition has increased the "total geraniol" (total acetylisable compounds) in oil. Magnesium in combination with phosphorus fertilizers significantly increased the total geraniol at the second harvest. The increase of total geraniol was always accompanied by the decrease of total hydrocarbons, which indicates the better utilization of monoterpenes in biosynthesis of constituents of total geraniol in oil as a result of phosphorus nitrition. Phosphorus content in leaves has positive relationships with total geraniol (r=+O.5), essential oil yield (r= +0.58) and output of total geraniol (r=+0.59). The optimum phosphorus concentrations in leaves after four months of planting that produced maximum yields of essential oil and total geraniol by this crop were found to be in the range of 0.23-0.26 %.