Effects of row distance on yield of two ecotypes of Thymbra spicata L. under field growing conditions

This research was conducted to investigate the effect of row spacing on yield (performance), morphological indices and essential oil content of two ecotypes of Thymbra (Thymbra spicata L.) in field growing conditions during two years of 2016 and 2017. The experiment was conducted in factorial based on randomized complete block design with three replications at the Research Farm of Faculty of Agriculture, Ilam University. The treatments consisted of three-row spacing (20, 30 and 45 cm) and two ecotypes (Malekshahi and Sumar). The results of the combined analysis revealed that plant spacing and ecotypes had a significant effect on many parameters such as dry matter yield of leaf and plant, percentage, essential oil yield, leaf area index, number of branches, number of flowers per plant and plant height. The comparison of the mean for simple and interaction effects of parameters showed that when row distance between plants increased up to 30 cm, plant dry matter yield, leaf area index, the number of branches and canopy diameter increased in the plant. According to the positive correlation of these parameters with essential oil yield, the highest yield of essential oil was observed in this treatment. Among the two ecotypes, the Malekshahi ecotype was superior to Sumar in terms of dry matter yield of leaf and plant, essential oil, percentage and yield, number of branches, canopy diameter and leaf area index. The results of two-year planting of Thymbra spicata indicated that the highest dry matter of plant yield, leaf area index, number of branches, canopy diameter, length of inflorescence and essential oil percentage were achieved in the second year of cultivation in the row spacing of 30 cm and Malekshahi ecotype.