Abstract:
Holistic improvements of oil yield and quality could be realised through integrating the knowledge of mycorrhizae and magnetic field stimulation. The main objective of this study was to determine the effect of Ca:Mg ratios and the inclusion of mycorrhizal fungi in the root media on the yield and oil quality of rose geranium exposed to static magnetic field (facing south). The experiment was structured as a 3×2 factorial experimental design, with three levels of Ca:Mg ratios (2.40:6.78, 4.31:4.39, and 6.78:2.40 meq L-1), two levels of MF (zero MF, denoted by 0MF, and 110.1 mT, denoted by 1MF), and two levels of mycorrhizae amendment (none, denoted by 0Myco, and 20 ml of mycorrhizae amendment per plant, denoted by 1Myco) as a split-plot factor. The results showed that the application of Ca and Mg in approximately equal proportions of 4.31 and 4.39 meq L-1 had significant effects on leaf Zn and stem Mg content. The application of Ca and Mg in equal proportions and in combination with either an MF or mycorrhizae had significant effects on plant height, chlorophyll content, stem N, stem Cu, and stem Zn contents. Furthermore, high Ca and low Mg (6.78:2.40 meq L-1) in the nutrient solution significantly reduced the concentration of Mg in the leaves. On the other hand, a ratio of high Ca to low Mg (6.78:2.40 meq L-1) in the nutrient solution caused a small increase in the Zn concentration in comparison to that resulting from a ratio of high Mg to low Ca (6.78:2.40 meq L-1) in the nutrient solution. Although plant height and the number of leaves per plant were affected by equal proportions of Mg and Ca with 1MF and mycorrhizae use, this effect did not increase the oil yield and C:G ratio which favour essential oil of rose geranium, but the oil quality was within the acceptable international range for perfume industry. A multivariate analysis was further used to determine eigenvalue of the correlation matrix. Amongst the observed variables, only two principal components, PC1 (27.23%) and PC2 (23.78%) accounted for more than half of the total variance. Multivariate analysis revealed the antagonistic and synergetic effects between mineral elements subjected to Ca to Mg ratio, MF and mycorrhizal fungi.
