MEDICINAL AND AROMATIC CROPS (2+1)

Cultivation

Soil
The crop is found growing on various types of soils from sandy loam to medium black. However, a fertile, well drained sandy loam soil which is rich in organic matter is ideal.

Climate
Season is an important aspect to be considered when davana is grown for extracting essential oil. The oil content in the plant was maximum when the crop was grown during the winter season compared to the other seasons. Thus, when the crop is grown for the production of oil it should be planted during the first week of November. A few light showers with moderate winter conditions and no frost is conducive to the good growth of the plant. High temperature and heavy rains at the time of flowering have not only been found to affect the plant growth adversely, but also reduces the oil content and ultimately the oil yield.

Nursery raising
Davana is propagated by seeds. As the seeds lose viability rapidly only the seeds from the previous season should be used for sowing. About 1.5kg of seed is required to produce enough seedlings to transplant into an area of one hectare.
Usually, nursery beds 2m long and 1m width are preferred. The surface of the beds should be clod free. It is then incorporated with finely prepared FYM at the rate of 10kg per bed. Sowing of seeds at the rate of 1g/sq m is desirable. The seeds may be sown either dry or after wetting them along with sand for about 48 hours. In the latter case, the seeds are thoroughly mixed with sand @ 4-5 times their volume. To this mixture, water is added so that the sand is sufficiently wet. It is then tied in a cloth bag and stored in a warm place for 48 hours. This will hasten the sprouting of seeds and radical will emerge at the end of 48 hours. The nursery bed is then flooded with water to make a pool and the sprouting seed and sand mixture is broadcasted all over the bed, homogeneously. This method helps in uniform distribution of seeds. When the seeds have settled down a thin layer of sand is spread over just enough to cover them. The seeds will germinate within 2-3 days of sowing. Hand watering is done till the seedlings establish themselves (7-10 days) after which the beds are irrigated directly though the water channels.
While sowing the dry seeds they are mixed with sand and in the ratio of 1: 10 and broadcasted homogeneously all over the bed. A thin layer of sand is then spread uniformly to cover the seeds and the beds are hand watered twice a day. To prevent the ants from carrying away the seeds an application of 10kg/ha of Heptachlor to the soil about 10 days prior sowing has been helpful. Using this method the germination of seeds is observed in about 4-5 days.
In areas where there are rains at the time of nursery raising, the seedlings may be grown on raised nursery beds which will also help in reducing the incidence of damping – off disease.
As there is very slow growth of seedlings initially, foliar spray of urea (0.1%) at weekly intervals, 3 weeks after sowing may be given to boost their growth.

Transplanting
The seedling will be ready for transplanting in about 6-8 weeks from the date of sowing. At this stage, the seedlings should be about 10cm tall.
Before transplanting the field is thoroughly prepared by bringing the land to a fine tilth with repeated ploughings. It is then laid out into plots of convenient size by laying out bunds and channels. The size of the plot depends on the conditions prevailing locally. However, generally, plots of 3-4 m x 1.5-2.0 m size are preferred as it facilitates irrigation, weeding and other intercultural operations. After the preparation of the plots, the soil is incorporated with 6 t/ha of well decomposed FYM or compost. The plots are irrigated a day prior to transplanting. The seedlings are then transplanted at a spacing of 15 cm between rows and 7.5cm between plants. Trials have shown that transplanting davana plants closer together results in higher herbage yield and subsequently, higher oil yield compared to wider spacing, which results in larger plants but lower herbage and oil yield per unit area.

Manures and Fertilizers
Davana responds well to the application of manures and fertilizers. Well decomposed FYM at the rate of 6t/ha is incorporated in to the soil at the time of land preparation. Subsequently, a fertilizer dose of 40kg P and 40kg K /ha is given at the time of transplanting. The N is applied at the rate of 120kg/ha in three equal split doses. The first dose is given at 10 days after transplanting and the subsequent two doses at 15 days intervals thereafter.

Irrigation
After transplanting, the plots are immediately provided with light irrigation. Later irrigation is provided daily till the seedlings are well established (10-12 days) and, subsequently once in 3-4 days depending on the weather conditions.

Interculture
The field is kept weed-free by regular weeding as and when required. In all about 2-3 hand weeding during the early period of growth will help to keep the weeds down.

Growth regulator application
Growth regulators have been used to boost the growth and yield in many crops. In davana also, an application of GA at 200 ppm after fives weeks of transplanting has been found to increase the herb and essential oil yield per unit area.

Pest and Diseases
Insect pests:
No serious attack of insect pests has been reported in davana. However, some insect pests like leaf eating caterpillars, aphids and termites have been observed to affect the crop.

Diseases
Damping off
The disease is caused by fungus belonging to the Rhizoctonia spp. It is usually severe at the nursery stage, particularly when there is high humidity and cloudy weather conditions resulting in the heavy mortality of seedlings. Controlling the irrigation will reduce the incidence of the disease. Treating the seeds with Emisan @ 0.2% before sowing and then drenching the seed beds with the above chemicals a week after germination controls the disease.