Evaluation of Changes in Alkaloid Content and some Physiological Traits of Datura stramonium L. under the Influence of Planting Date and Plant Density Levels

Introduction Datura stramonium L. is one of the medicinal plants that have a special role in the pharmaceutical industry due to its alkaloid compounds. Datura is one of the most important medicinal species that is a rich source of alkaloid compounds. Important phytochemical compounds in Datura, especially alkaloids, have been considered by the pharmaceutical industry. Datura (Datura stramonium L.) is an annual plant of the Solanaceae family, which is native to North America and is found in abundance in the coastal areas of northern Iran from Astara to eastern Mazandaran. Important phytochemical compounds in tattoos, especially alkaloids, have been considered by the pharmaceutical industry. Tropane alkaloids are one of the most important compounds in plants of the Solanaceae family and the anticholinergic effects of these compounds have made their use common in medicine. Important tropane alkaloids include hyoscyamine, ascopolamine, and atropine in D. stramonium. Plant growth is a set of specific biochemical and physiological processes that interact with each other and are affected by environmental factors such as temperature, light intensity, etc. that are affected by the date of planting. In the meantime, analyzing the amounts of photosynthetic pigments is a way to justify and interpret the plant's reactions to different environmental conditions during the growing period, through which it is possible to transfer and accumulate photosynthetic products. Due to the importance of D. stramonium and its widespread use in the pharmaceutical industry, Since Datura plant has not been adequately studied in the literature, the purpose of investigating three different planting date and planting density levels in this plant is to determine their proper values which increase the alkaloids and photosynthetic pigments, resulting in grain growth and yield increment. Materials and Methods This research during two consecutive years (1397-1397 and 1397-1398) in Shahid Fozveh research station affiliated to Isfahan Agricultural Research and Training Center and Natural Resources located 25 km west of Isfahan (Latitude: 32°36′37″ N, Longitude: 51°26′52″ E . 1612 m above sea level), which according to the Gauchen division has a mild semi-desert climate. The experiment was performed as a factorial experiment in the form of randomized complete blocks with three replications. Treatments included three densities (6, 10 and 14) plants per square meter and planting date in autumn and spring. Autumn planting of D. stramonium for the first year of the experiment was done on 3 January and in the second year on 30 December. In the spring planting of D. stramonium, due to the long growing season, in order to be productive during the growing season, first the seed of the plant was planted in the planting trays and then in the 3 to 4 leaf stage the seedlings were transferred to the main land. In both years of testing, the seeds were sown on the date of spring planting in March. Field operations including plowing, disc, leveling, preparation and preparation of atmosphere and ridges were carried out in the field. According to different fertilizer levels and density levels, each replication included 9 experimental plots. The length of each plot was 5 m and its width was 3 m, which included 5 rows with a distance of 60 cm. The distances of the plants on the ridge were considered as 15, 20 and 33 cm 33, respectively, according to the densities (6, 10 and 14 plants per square meter). The distance between the replicates was 1 m and the distance between the plots from each other was considered a planting line. The data were analyzed using SAS software version 9.4. The means were compared with LSD test at 5% level and graphs were drawn using EXCEL software version 2010. Conclusion  According to the results, the density of 6 plants per hectare on the date of autumn planting improved seed yield and increased hyoscyamine and alkaloids. In fact, the density of 6 plants per square meter in this study increased grain yield and the amount of hyoscyamine and ascopolamine. At low plant densities in this study, including densities of 6 and 10 plants per square meter, the amount of photosynthetic pigments increased. Also, maintaining the amount of chlorophyll in young leaves causes a delay in the aging process and increases the durability of the leaf surface, which will have a significant effect on the transfer of photosynthetic material to the seed. More and slower nourishing material is transferred to the grain, so the grain filling period will be longer. The results show that by selecting proper levels of plant density and planting date as two of the most important crop management practices, the number of tropane alkaloids in Datura as one of the important active ingredients in the pharmaceutical industry increases.