improvement of the yield and essential oils quantitative in calendula (calendula officinalis l.) by using different planting arrangement and potassium fertilizer

this study was done to evaluate the effect of different planting arrangements (square, lozenge and rectangular) and various concentrations of potassium sulfate (k2so4) fertilizer (0, 100, 200 and 300 kg/ha) on yield and essential oils quantitative of calendula officinalis l., a medicinal and ornamental plant. the experiment was done as a factorial in randomized completely blocks design (r.c.b.d.) with 3 replications. the results showed that the plant height, the number of flowers, flowers dry weight, potassium content of aerial part, flower essential oil and carotenoids content in petals were significantly increased. the highest plant height (54.18 cm) was calculated from plants grown under 200 kg/ha k2so4 and rectangular arrangement. maximum number of flowers per square meter (727.93), flower dry weight per square meter (140.58 g), potassium content of aerial part (0.9 mg/l), essential oils content per square meter (0.27 g) and carotenoids content in petals (8.24 mg/l) were obtained from plants grown under soil conditions containing 300 kg/ha k2so4 and with square arrangement. the results of current study recommend using of 300 kg/ha of k2so4 and square planting arrangement for increasing the yield and essential oils content of calendula.