The Effect of Planting Density and Number of Hand Weeding Times on Weeds Control and Relationship Between Morphological Characteristics With Content and Yield of Essential Oil of Satureja Hortensis L.

The aim of this study was to evaluate the effect of planting density and number of weeding times on weeds control and the relationship between morphological characteristics with the content and yield of Satureja hortensis essential oil (EO). S. hortensis planting density at four levels (50, 75, 100 and 125 plants per m2) was the first factor and hand weeding in 4 times (2, 4, 6 and 8 weeks after planting- WAP), 3 times (2, 4 and 8 WAP), 2 times (4 and 8 WAP) and weedy check as second factor. Dominant weeds were included redroot pigweed (Amaranthus retroflex L.), black nightshade (Solanum nigrum L.) and lambsquarters (Chenopodium album L.) in this field. Increasing Satureja hortensis density under densities of 50, 75 and 100 plants per m2 with weeding especially four times, significantly increased the dry weight and content of EO and yield of this plant. But the delay in the weeding times, such as twice weeding, significantly reduced this trait. This indicates that weeding in S. hortensis should be done at the beginning of the growing season due to its slow growth. Also, increasing the density of S. hortensis from 100 to 125 plants per m2 intensifies competition, so that its EO yield content decreased despite increasing the number of weeding times compared to the weedy check. Overall, due to the favorable effect of weed control under three or four weeding times on dry weight and content and EO yield of S. hortensis, weeding at the mentioned times is recommended in Gonbad Kavous area and areas with similar conditions to Gonbad Kavous.