Evaluation of Morphological Traits and Yield of Satureja bachtiarica Affected by Density and Organic Fertilizers under Dryland Farming Conditions

Savory plant (Satureja bachtiarica) belonging to the Lamiaceae family and the genus Satureja is considered as a valuable medicinal plant. Flowering branches are widely used in food and pharmaceutical industries. This plant is native of Iran and grows well in the western, southwestern and central regions of Iran. Cultivation of permanent medicinal plants adapted to the dryland farming conditions of each region can be the best option for alternative annual cereal cultivation. Establishment of permanent medicinal plants, while creating suitable vegetation, can prevent erosion caused by repeated annual plowing. One of the main pillars in sustainable agriculture is the use of organic fertilizers in crop ecosystems with the aim of eliminating or significantly reducing the harms of chemical fertilizers. Organic fertilizers help to human health and environment. Also it is absolutely evident the importance of their application to medicinal plants that are directly related to human health. In dryland farming condition, plant density is an effective strategy to improve plant yield, which depends on climate and rainfall. At optimum density, plants make the most of environmental factors such as light, moisture, and nutrients. Plant density per unit area is one of the important factors in creating competition among plants. The appropriate distance between planting rows and between plants on the row are usable growth space of each plant. Proper density is one of the important factors in the success of dry farming of medicinal plants. Therefore, achieving proper density in different areas is very important.

An experiment was conducted as a split plot based on randomized complete block design with three replications at Homand rangeland research station of Damavand in 2017 and 2018 in dryland farming conditions. Organic fertilizer as a main factor included three levels of cattle manure (30 tons ha-1), wheat straw (10 tons ha-1) enriched with ammonium sulfate, and control (no fertilizer). Plant density included three levels of 26666, 40000, and 80000 plants ha-1 as a sub-factor. Measured traits included plant height, canopy area, number of main branches, shoot dry matter yield, percentage of dry weight to fresh weight of plant, and percentage of moisture to dry soil at 0-20 and 20-40 cm depths. Analysis of variance was performed using SPSS software. The statistical significance of differences in mean values was assessed by Duncan's multiple range test.

The results showed significant differences between treatments in measured traits. Among the measured traits, the effect of organic fertilizer and plant density on plant height, canopy area, number of main branches, shoot dry matter yield were significant at 1% level. The interaction effect of year, organic fertilizer and plant density showed that the highest of shoot dry matter yield (426 kg ha-1) was related to cattle manure application and high plant density in second year. The highest plant height and number of main branches were observed 34 cm and 29 numbers, respectively in treatment of cattle manure and second year. Organic fertilizers increased the storage capacity of soil moisture and created suitable conditions for growth and increased the biological Satureja bachtiarica yield. Improving soil structure and nutrients and better root growth increased plant growth and yield due to the use of organic fertilizers. The plant density due to higher plant per unit area, plant competition, optimal use of available space, and also establishment and more plant growth in the second year increased significantly the Satureja bachtiarica yield.

This study showed that understanding the success of establishment and full tolerance of this plant under dryland farming conditions and the minimum soil moisture in the cold semi-steppe region (Damavand) with an average rainfall about 340 mm per year and also the use of cattle manure and high plant density can increase the economic yield of Satureja bachtiarica in second year of cultivation.