Effect of transplanting date and plant density on dry matter and total phenol in shoot of purple coneflower in Sari

This experiment was conducted with three transplanting dates (April 9, May 9 and June 8 2013) and three plant population densities (7, 10 and 16 plant/m2) which considered as main and subplots, respectively. Results showed a relative compensatory effect of higher population density until 10 plants/m2, albeit delayed planting resulted to decrease in total shoot, leaf (L) and stem (S) dry weights. It represents that the highest flower dry weight (F) (27.1 g/plant) was related to planting on May 9 with 10 plant/m2 density. Ratio of L/shoot was greater than S/Shoot than F/shoot. The highest (L)/Shoot ratio was related to the April and May planting dates while the highest S/Shoot ratio was related June’s planting date. Maximum total phenol content of leaves (51.1 mg of GAE/ g dry matter) and stems (35.9 mg of GAE/ g dry matter) were measured in plants cultivated on April 9 with a density of 10 plant/m2. The highest total phenolic content of flowers (56.5 mg of GAE/ g dry matter) was determined in plants cultivated on May 9 with a density of 10 plant/m2.Total phenol of flowers was greater than leaves than stems. Overall, it could be concluded that early planting of purple coneflower on April 9 with 10 plant/m2 density is apparently suitable for leaf and stem dry weight and total phenol production while delayed planting until May 9 with a population density of 10 plant/m2 is favorite for flower based production of dry weight and total phenol, according to the experiment conditions.