Cultivation

Cultivation

    Soil
    The crop is hardy and grows well on a wide variety of soils, except those which are alkaline or water- logged. Deep sandy loam to loam soils of medium fertility are preferred for its large scale cultivation because of better development of roots and also easy to collect at harvest time.

    Climate
    The distribution of the plant shows that there is no specificity in its climatic requirements. It comes up well in tropical and subtropical areas. However the growth in tropical areas is better than in the subtropical areas, where its growth is slow due to the low temperature in winter. It can be successfully grown up to an elevation of 1300 m above sea level. A well distributed rainfall of 100 cm or more is ideal for raising this crop on commercial scale under rain-fed conditions.

    Propagation
    The plants can either be propagated by seeds or vegetatively through cuttings. Since plants propagated by cuttings flower earlier than the plants from seeds, it is recommended that for drug production the plants should be grown from seeds and for seed production from cuttings.

    Propagation by seeds
    Fresh seeds collected a few months in advance are preferred for sowing as they lose viability on long storage. The seeds can either be directly sown in the field or a nursery can be raised and the seedlings are transplanted.

    Direct Sowing
    This method is best suited for large areas where labour is expensive as it reduces the cost of production. The land is ploughed twice and brought to fine tilth. Weeds, stubble and pebbles are removed. The field is divided into plots of convenient size and the soil is mixed with the recommended dose of manures and fertilizers. The seeds at the rate of 2.5kg/ha are broadcasted at the onset of monsoon in June – July, in lines spaced 30 -45 cm apart and lightly covered. Since the seeds are very small, for ease in handling and distribution, they are mixed with sand about 10 times their weight. Germination takes place after about 7 – 8 days. After germination is complete the seedlings are thinned at a spacing of 30 – 40 cm within the row. The flowering starts 40 – 45 days after sowing.

    Nursery preparation and transplanting
    When seed supply is short this method can be followed. The other advantage of this method in comparison to direct sowing is that healthy and vigorously growing seedlings can be selected and the inferior ones can be discarded. The seeds are sown in well prepared, raised nursery beds in March – April in rows spaced at 8 – 10 cm apart and about 1.5cm deep. About 500 gm of seeds will be enough to raise seedlings to cover 1 ha area. After two months of germination, the seedlings are ready for transplanting into the field. The seedlings are transplanted at a spacing of 45 x 30 cm in the field. A population of 74, 000 plants per ha may be accommodated.

    Vegetative propagation
    To raise plants by this method, soft wood cuttings obtained from the lateral shoots have proved better than either hard or semi hard wood cuttings. Cuttings of about 10 – 15 cm length with a minimum of 5-6 nodes are ideal and result in about 90% rooting. Soaking the cuttings over night in NAA solution of 25 or 50 ppm concentration has been found to further improve rooting to the extent of 96%. This method can be profitably used for multiplying the clones which have high alkaloid content and also where seed alone is to be produced.

    Manures and fertilizers
    FYM is applied at the rate of 10 – 15 t/ha to obtain good growth and yield. If irrigation is available, green manure crops can be raised and ploughed into the field at the time of flowering. In case organic manure is not applied it is advisable to apply a basal dose of 20 kg N, 30 kg P2O5 and 30 kg of K2O per hectare per year. In addition, a top dressing with 20 kg nitrogen can be given in two equal split doses during the season.

    Irrigation
    In places where rainfall is evenly distributed throughout the year, the plants do not require any irrigation. However in areas where rainfall is restricted to a few months in a particular period, about 4-5 irrigations will help the plants to give optimum yield.

    Weed control
    The crop requires two weedings in the initial stages of its growth. The first weeding may be done after about 60 days of sowing and the second at 120 days of sowing. Mulching the field with cut grass or rice straw will also minimize the weed growth.

Last modified: Tuesday, 3 April 2012, 5:38 AM