Effect of Sowing Date and Various Potassium Levels on Quantitative Yield of Pot Marigold Medicinal Plant (Calendula officinalis L.)

In order to evaluation the effect of sowing date and various of potassium levels on quality and quantity yield of Pat Marigold a field experiment was conducted at field research , Faculty of Agriculture, Mashhad Branch, Islamic Azad university, Mashhad, Iran, in during cropping season 2011- 2012. The experimental design was randomized complete block design (RCBD) arranged in a factorial with three replication. Factors were included sowing date in three levels (30 May, 9 and 19 June), and potassium (K_2 O_5) in three levels (0, 40 and 80 kg/ha). Analysis of variance showed that the effect of sowing date and potassium on fresh flower yield (ton/ha), dry flower yield (Ton/ha) and essential oil were significant. Nevertheless, the effect of sowing date and potassium on percentage of essential oil were not significant. Interaction between two factors had signification effect on essential oil yield. The results of mean comparison showed that the highest fresh and dry flower yield per hectare (1.9 and 8.4 ton/h respectively) and essential yield (81.9 kg/h) were obtained in third sowing date (19 June).Also, the highest rate of all traits were obtained in 40 and 80 kg/ha of potassium .but, these levels of potassium had not significant difference, while difference with control (0 kg/h of potassium) was significant.