Effect of varying concentrations and time of Nano-iron foliar application on the yield and essential oil of Pot marigold

ABSTRACT: To evaluate the effect of iron on the flower and essential oil yield of Pot Marigold (Calendula officinalis), a field experiment as factorial was carried out based on randomized complete block design with three replications at the Research Farm of Urmia University (latitude 37.53 N, 45.08 E, and 1320 m above sea level), Urmia, Iran in 2011. Treatments were iron concentration (0, 1, 2 and 3 g/liter) and spraying stage (foliar application at stem initialize, flowering, after first and second harvest). Results of ANOVA showed the significant effect of spraying time (growth stage) on the yield of flower at first and second harvest, essential oil percent at the first harvest, the essential oil yield at the third harvest. The effect of Nano-iron concentration was significant on the yield of flower at second harvest and on the yield of essential oil at first harvest. However, there was a significant interaction effect between iron spraying time and concentration on the yield of flower at third harvest. The highest yield of flower at first harvest (405.37 kg/ha) was obtained from Nano– iron foliar application at stem initialized, and the lowest yield of flower (261.64 kg/ha) belonged to iron – spraying after second harvest. Trend of flower yield at second harvest was the same with the yield obtained from first harvest. The highest yield of flower at third harvest (145.69 kg/ha) was obtained from 1 g/liter at stem initialized. But the latest application showed fewer yields than Control. At the second harvest, the highest (1.573%) and lowest (0.981%) percentage of essential oil were obtained from plants sprayed at stem initialized and after second harvest, respectively. The highest yield of flower and percent of essential oil in Nano – iron application at stem initialized (early usage) led to the highest yield of essential oil (2.397 kg/ha) in this treatment.