Coleus (Patharchur)


Plant Profile

Cultivation
Soil
It thrives best in porous and wall-drained soils with a pH ranging form 5.5 t0 7. it dose not require very fertile soils and can be economically be grown on soils of Karnataka are ideal for the cultivation of this crop.
Climate
Coleus is a crop of the tropics and is found growing well on barren hills at an altitude of about 2400m, under tropical and subtropical conditions. In India, it is grown mainly in Belgaum (the Sahayadri mountain range of Karnataka) and in Gujarat. The Climate here is humid with a RH ranging from 83 to 95% and a temperature of 10-25o C. The annual rainfalls in 100-160 cm, mainly between June-September. It is also found to performs well in less humid and warmer regions of South India like Coimbatora, where it is grown as an irrigated crop.
Propagation
Coleus can be propagated by seeds as well as by stem-cuttings. However, propagation through seeds is little difficult and slow and should be used only for the breeding of new varieties. Whereas, propagation by cuttings is very easy and economical to raise this crops on large scale.
Nursery Raising
The viability of the seeds being very poor (8-10%) a sufficient quantity of fresh seeds has to be sown in well prepared nursery-beds to obtain good germination. Regular care about watering, weeding and plant protection of the nursery should be taken. In about 15 to 20 days, the germination is completed. When the seedling are 45 days old and have attained about 8-10 cm height, they are ready for transplanting.
Vegetative Propagation
Vegetatively, the crop is propagated through terminal cuttings. Normally, 10-12 cm-long cuttings, comprising of 3-4 pairs of leaves, are sown in already prepared nursery-beds and regular care about shading and watering is taken. The cuttings establish well in the nurseries and there is no problem in their rooting. After about a month’s time, when the cuttings have produced sufficient roots, they are transplanted to the main field.
Planting
In most areas, the crop is planted during June-July at the onset of the Southwest monsoon. Before planting, the field is ploughed deep soon after the of pre-monsoon showers and furrows at a spacing of 60 cm and the rooted cuttings or seedlings are planted 20 cm apart within the row.
Manures and Fertilizers
Studies conducted at TNAU. Coimbatora, to standardize the nutritional requirement of this crop have shown that it responds well to the application of N.P. and K.A. combination of 40 kg N. 60 kg P2O5 and 50 Kg KO2 has was found to be optimum for obtaining the maximum fresh (120t/ha) and dry (3.982 t/ha) tuber yield from this crop Half the dose of N, the whole P and whole K may be applied as the basal dose after planting as top-dressing.
Irrigation
The first irrigation is given immediately after transplanting, if there are no rains, During the first two weeks after planting, the crop is irrigated once in three days and thereafter, weekly irrigation is enough to obtain good growth and yield.
Weeding
Due to the frequent irrigations during the initial stages, there is a lot of competition from weeks. In order to obtain economic yield, frequent weeding during the early growth period is desirable.
Pest and Diseases
Pest
The leaf-eating caterpillars, mealy bugs and root knot nematodes are the important pests that attack this crop. These insects can be controlled by spraying the plants and drenching their roots with 0.1% menthyl parathion, while nematodes can be controlled by the application of carbofuran granules at the rate of 20 kg/ha.
Diseases
Among the disease, bacterial wilt is the major one. The spread of wit can be controlled by spraying and drenching the soil adjoining the affected plants with 0.2% Captan solution immediately after the appearance of the disease and later after a week’s interval.
Harvesting and Yield
Flowers, if any should be nipped off during the growing period to obtain more biomass of roots. The crop is ready for harvest 41/2 to 5 months after planting. The plants are loosened, uprooted, the tubers separated, cleaned and sun-dried for the extraction of “forskolin”.
On an average, a yield of 1500-2000 kg/ha of dry tubers may be obtained. However, if proper cultivation practices are applied, a yield of up to 2500 kg/ha. of dry tubers can be easily obtained.
Source: AMALTAS, Issue 3, Vol. No-1, March 2005.