أستجابة البردقوش الحلوOriganum majorana L. للثيوريا والبورون ومحتواه من الزيوت الطيّارة

Response of sweet marjoram Origanum majorana L. to thiourea and boron and its volatile oil content

The experiment was carried out in the shade of the Horticulture and Landscape Department – College of Agriculture – University of Kerbala during the spring season of 2024, from 25-2-2024 to 1-7-2024, in order to study the effect of spraying with thiourea and boron and the interaction between them on vegetative and root growth, chemical content, and the content and components of volatile oils in the sweet marjoram plant. The study was conducted as a factorial experiment according to a randomized complete block design (RCBD) with three replicates. The experiment included 16 treatments consisting of 4 concentrations of thiourea 0, 500, 750, 1000 mg L-1 (referred to as T3, T2, T1, T0) respectively and 4 concentrations of boron 0, 25, 50, 100 mg L-1 (referred to as B3, B2, B1, B0) respectively. The experimental data were statistically analyzed using the Genestat statistical program, and the means were compared using the least significant difference (LSD) test at a probability level of 0.05. The most important results were obtained, as shown below:
1- The effect of spraying with thiourea and boron individually was significant on most of the vegetative, root, and chemical characteristics, and the plant content of active compounds found in volatile oils.
2- The effect of interaction between the two study factors was significant, as the highest average for the plant height trait was recorded in treatment (T1B3), reaching (29.45 cm), while the stem diameter trait, number of branches, and root length traits were superior to treatment (T3B2), giving the highest average of (2.080 mm), (18.68 branch plant-1), and (16.633 cm), respectively. As for the leaf area trait and root size trait, the interaction treatment (T2B2) gave the highest average of (1.137 cm2) and (1.667 cm3), respectively, while the
percentage of dry matter of the vegetative group was superior to the interaction treatment (T3B3), as it gave the highest average of (24.97%), as well as the highest average for the percentage of dry matter of the root group, reaching (86.27%) in the same treatment. The chemical content of the plant was also significantly affected by the study factors, as the highest average reached (57.91) mg. 100g-1 fresh weight) for the total chlorophyll content in the treatment (T3B2) and also gave the highest average percentage of phosphorus (0.4592%), while the content of carbohydrates, protein, nitrogen, potassium, sulfur and boron was superior to the interaction treatment (T3B3) and gave the highest average of (37.832 mg 100g-1 dry weight) carbohydrates (18.604%) protein and (2.9767%) nitrogen (1.8868%) potassium, and the highest average concentration of sulfur in the plant reached (92.87) mg L-1), and the highest average concentration of boron in the plant reached (38.70) mg L-1). As for the plant content of active compounds present in the volatile oil, the effect of the interaction of treatments on the average content of the compounds was significant. Treatment (T3B3) gave the highest average plant content of the compound Terpinene 4-ol, which amounted to (569.42 µg ml-1) and Cis sabinene hydrate, which amounted to (424.14 µg ml-1). Treatment (T2B3) gave the highest average of the compound Terpene-α, which amounted to (244.02 µg ml-1), and treatment (T2B1) gave the highest average of the compound Thymol, which amounted to (207.35 µg ml-1). As for the interaction treatment (T3B2), it gave the highest averages for the compounds Cymene-β and Carvone, which amounted to (230.73 µg ml-1) and (202.30 µg ml-1), respectively.