Effect of compost and titanium dioxide application on the vegetative yield and essential oil composition of coriander

Coriander is one of the most popular and intensely used spices owing to its multipurpose uses worldwide. It is mainly cultivated for the production of its dried seed and fresh leaves. The present study aimed to evaluate the application of compost and foliar spraying of TiO2 on the yield and essential oil composition of coriander. Two field experiments were conducted during two successive seasons; after that, the yield parameters were determined, and the essential oil of the seeds was extracted and analyzed via gas chromatography-mass spectrometry (GC-MS). Results indicated that coriander growths at both years were significantly affected by compost application and foliar application of TiO2, and a significant interaction of these two factors also occurred. Compost application at 50 m3 caused significant increments of 55% and 46% in umbels number and 75% and 64% in seed yield in the first and second season, respectively, compared with control. The application of compost to the coriander plant significantly influenced oil percentage and oil yield per ha. The maximum oil percent was recorded in control plants. Foliar application of TiO2 resulted in significant improvement in plant height, number of umbels, and seed yield of coriander as compared with control and reached their maximum values at 6 g L−1 compared with the control; foliar application of TiO2 at 2 g L−1 enhanced numbers of umbels by 22% with no significant differences between 2, 4, and 6 g L−1 treatments in the first season and by 24, 33, and 48% in the second season. Increases in seed yield accounted for 34, 43, and 64% in the first season and 21, 36, and 45% in the second season due to titanium dioxide application of 2, 4, and 6 g L−1, respectively. The maximum content of linalool (87.61%) and minimum content of estragole (0.7%) was recorded at 4 g L−1 titanium dioxide with no compost.