Effects of nitrogen and density on growth and Datura stramonium L. yield

Datura stramonium L. is one of the important medicinal plants in the pharmaceutical industry due to its alkaloid compounds. To investigate the effects of urea fertilizer at three levels (60, 120, and 180 kg.ha-1) and planting density at three levels (6, 10, and 14 plants.m-2) on the yield and yield components of this plant species, a factorial experiment was conducted in a randomized complete block design in the research farm of Isfahan Agricultural and Natural Resources Research and Education Center, Iran in 2018 and 2019 crop years. The main effects of density and urea on the traits including height, number of lateral branches, and 1000-seed weight and the interaction of different urea and density levels on the traits including seed yield, biological yield, number of capsules per plant, number of seeds per plant, and number of seeds per capsule were significant in both years. The highest seed yield (1282.37 and 1212.53 kg.ha-1, respectively in 2018 and 2019 years) was obtained in the urea fertilizer 180 kg.ha-1 and 6 plants.m-2 treatment. The causal analysis results showed that the highest direct positive effect at the different levels of density and urea was related to the number of capsules per plant. The results of this experiment showed that the application of 180 kg.ha-1 of urea and 6 plants.m-2 could play an important role in increasing the seed yield of medicinal plant D. stramonium.