MEDICINAL AND AROMATIC CROPS (2+1)

Cultivation

Soil

A well drained loamy soil with a pH of 6 to 7 with irrigation facilities is ideal for the cultivation of palmarosa. A rise in pH above 8.5 is found to decrease the growth and consequently the oil yield, but has no adverse influence on the quality of oil produced. It also grows well in well-drained clayey loam soils, free from water-logging. If the soil is not well drained or if after heavy irrigation, the water remains standing in the hot weather, the growth of the grass is badly affected.

Climate
Palmarosa is a crop which grows well in a warm tropical climate with an elevation of up to 300m. Locations with an annual variation in temperature between 10 to 36° C and the rainfall around 150cm, with ample sunshine are the best suited for its cultivation. Areas which are affected by severe frost are not suitable, as the frost kills the grass and reduces the oil content.

Land Preparation
The field is prepared well before the onset of the monsoon. It is ploughed and harrowed to a fine tilth. All the stubble and roots of weeds are removed. At the time of the last ploughing, FYM @ 10t/ha is incorporated into the soil.
Healthy and established seedlings which are 15cm high are carefully removed from the nursery and planted in rows at 60 cm x 60cm apart. In fertile areas, the spacing should be increased. It has been demonstrated at the CIMAP, Lucknow, that a closer plant spacing of 30 x 30 cm improves the palmarosa oil production by 44% over the planting at 60 x 30cm.

Propagation
It is best raised by

i) transplanting the nursery raised seedlings
ii) by root cuttings of healthy plants and
iii) through slips.

For commercial planting the crop is propagated through seeds.

Nursery raising
The nursery beds are prepared in May. Raised beds are preferable as the seeds are not washed off by irrigation. Liberal amounts of FYM should be added to the seed bed. As the seeds are small and light, they are mixed with fine soil in the ratio of 1:10 for even distribution and ease in sowing. They are sown in lines at 15-20cm apart. The seeds should not be sown densely as this will lead to crowding of seedlings, resulting in poor growth of the plants. About 2.5 kg of seeds are adequate to give enough seedlings for planting one hectare. The beds are watered lightly and regularly. Germination starts within two weeks. Later on a weak solution of urea (0.2 -0.5%) may be given for their good growth. In about 3 to 4 weeks the seedlings are ready for transplanting.

Slips
Plants that give yield and high quality oil should be used for taking slips. In this way it is possible to raise plantations yielding high quality oil, which is not possible when the plantation is raised from seeds as the seeds give rise to many morphologically indistinguishable but different varieties. However, the rate of establishment of rooted slips is very poor as compared to nursery transplants. Slips can be planted in June- July during the rainy season.

Planting
The seedlings are transplanted into the prepared fields as soon as the rainy season sets in (June- July).They can be transplanted even earlier, if the weather is not very warm and irrigation is available.

Manures and fertilizers
As the grass is perennial it is necessary to replenish the soil. In rich soils, manuring may not be required for the first two years. By manuring already rich soils, the vegetative growth is increased and the oil content is reduced. However for deficient soils a mixture consisting of 20kg N, 50kg P2O5 and 40kg K2O/ha is used as a basal dose at the planting. About 40kg/ha of N is applied in three split doses after each harvest. The mixture of N, P and K should be repeated at the time of the appearance of fresh leaves each year.
A foliar spray of FeSO4 and MnSO4 has been found to improve the plant growth, herbage and oil yield of palmarosa. The CIMAP, Lucknow, has also recommended an application of 10kg/ha of Zn which is reported to significantly increase the number of tillers, herbage and oil yield without affecting the oil content and quality. Similar results were obtained by the application of 20kg/ha of sulphur in the form of elemental sulphur or ammonium sulphate.

Irrigation
The irrigation required depends upon the climatic conditions. The grass requires irrigation after about 8-10 days during the growing season. With an ample supply of water, growth is luxuriant, but if drought prevails the growth is arrested, the leaves wither and the oil content is reduced. However, before harvesting irrigation should be discontinued.

Weeding
Odour is an important factor of the oil quality and it is essential to keep the fields clean of other growing plants, particularly those which impart their own odour. Therefore, the plantation should be kept free from weeds by regular weeding and hoeing. Particular care is required in the initial stage of growth, so that the weeds do not over power the grass. Diuron (1.5kg a.i./ha), Isoproturon 90.25kg a.i./ha) and oxyfluofen (1.5kga.i./ha) are the weedicides recommended to control weeds in palmarosa.

Pests and diseases
The crop is not attacked by any pest or disease of a serious nature. Leaf blight and the symptoms of yellowing of leaves and necrosis and leaf spot are reported in the crop.