Effects of nutrient solution concentration and soil substrate ratio on the cutting propagation of oregano

Improving the growth of oregano (Origanum vulgare) root system and increasing the rate of strong seeding represents the main technical problem of its cutting propagation. This study aimed at investigating the effects of nutrient solution concentration and soil substrate ratio on the cutting propagation of Greek oregano (O. vulgare ssp. hirtum), a perennial plant belonging to the family Labiatae. The results showed that the fresh weight, branch number, plant height, total root length, root surface area, root volume, number of root tips, and capillary root length and volume initially increased then decreased along with higher concentrations of macroelements in Hoagland's nutrient solution. Among these, the 0.25 × nutrient solution yielded the best effects with 242% and 464% of higher fresh weight and root volume than those of the water control, respectively. Furthermore, different combinations of soil substrates with peat and vermiculite also significantly affected the survival rate and growth indices of the oregano cuttings (P < 0.05); among which peat ꞉ vermiculite at 25 ꞉ 75 (volume ratio) showed the best effects on the survival rate (100%), growth, and root development of oregano cuttings. Therefore, the optimal condition for vegetative propagation of oregano is using peat soil substrate including vermiculite at 25 ꞉ 75 and weekly irrigation with 0.25 × Hoagland's nutrient solution.