Effects of soil and foliar applications of iron and zinc on flowering and essential oil of chamomile at greenhouse conditions

In order to study the effects of soil and foliar applications of iron (Fe) and zinc (Zn) on flowering, flower yield and essential oil production of German chamomile a pot experiment was conducted under greenhouse conditions at the Faculty of Agriculture, University of Tabriz, Iran in 2012. The experiment was arranged as completely randomized design with 12 treatments and three replications. Treatments were as follow: T1: control – without Fe or Zn fertilizers, T2: 30 mg FeSO4.7H2O kg-1 dry soil, T3: 22 mg ZnSO4.7H2O kg-1 dry soil, T4: 30 mg FeSO4.7H2O + 22 mg ZnSO4.7H2O kg-1 dry soil, T5: foliar spraying of FeSO4.7H2O (3.5 g L-1), T6: foliar spraying of FeSO4.7H2O (7.0 g L-1), T7: foliar spraying of ZnSO4.7H2O (2.5 g L-1), T8: foliar spraying of ZnSO4.7H2O (5.0 g L-1), T9: T5+T7, T10: T5+T8, T11: T6+T7, T12: T6+T8. The foliar spraying was done two times during the growing period. The results revealed that the flower number, flower yield, essential oil content and essential oil yield were significantly increased by soil and foliar applications of Fe + Zn, compared with the control (untreated). The highest flower number (477 plant-1), flower yield (11.6 g pot-1), essential oil content (0.88 %) and essential oil yield (119 mg pot-1) were recorded for the soil application of Fe + Zn (T4) by 58, 68, 21.4 and 105 % increment compared to the control, respectively. Foliar application of Fe + Zn (T12) was placed at the next rank; however this treatment had no significant difference with the soil application of Fe + Zn (T4). Other treatments did not show significant differences with the control. Generally, the results showed that soil or foliar application of Fe + Zn can be effective on increase or improve of quantity and quality of chamomile yield. Moreover, use of foliar application as a low cost method especially in areas with alkaline or calcareous soils can be recommended.