Effects of Plant Growth Regulators and Foliar Nutrients on the Alkaloid Content in Poppy Straw of Opium Poppy (Papaver somniferum L.)

Poppy (Papaver somniferum L.) is an important industrial plant worldwide. It is legally cultivated in seven countries around the world for the production of poppy straw or raw opium in India for alkaloid extraction. This work focused on testing different types of growth regulators and foliar nutrients to increase and stabilize basic alkaloids, mainly morphine in dry capsules. Field trials were carried out for three years (2021–2023). Selected preparations and their combinations were applied on the seeds before sowing and on the leaves during vegetation. The content of basic alkaloids in the dry capsules was analyzed by liquid chromatography. The results obtained confirmed the demonstrable effects of pre-sowing seed treatment and foliar treatment during the growing season on alkaloid content. In the experimental treatments in which the seeds were not treated but foliar treatment was applied during vegetation, more alkaloids were accumulated compared to the control (untreated seeds, not foliar treatment), but this difference was not statistically significant. The influence of the weather conditions during the experimental year on the accumulation of alkaloids was confirmed. Environmental conditions during the growing season and plant stress influenced alkaloid accumulation. An additional supply of growth regulators and foliar fertilizers reduced the stress and positively influenced the accumulation of individual alkaloids. The results obtained provide important insights into the technology of cultivating industrial poppy varieties.