Study the effect of plant density and nitrogen fertilizer on seed yield and yield components of milk thistle (Silybum marianum (L))

Milk thistle (Silybum marianum) is an important annul /biennial herbaceous plant belonging to the Asteraceae family. The effective substance of this plant is used for treatment of chronic hepatitis liver cirrhosis, liver toxic damages caused by alcohol and mushroom poisoning and stomach problems. To study the effect of plant density and N-fertilizer on seed yield and yield components, an experiment was conducted in factorial experiment with in a randomized complete blocks design with three replication in spring 2005 at research station of Hamand Absard. The treatments were plant density (50×20-50×30-50×40 cm2)and N-fertilizer (0-50-100-150kg/hec).The results indicate that the a decrease in plant density and an increase in N-fertilizer, significantly increased the diameters and the numbers of capitols in each plant. Also increasing N-fertilizer and plant density has a positive effect on plant height and seed yield, although the seed yield of each plant was decreased by increasing the plant density.