Species and varieties

Species and varieties

    D. deltoidea Wall (2n=20)
    It is an indigenous species found growing wild in the North-western Himalayas. It produces very slender vines and is very weak. It is propagated by tuber pieces, but the regeneration of tubers is so slow that it takes about 7-10 years to fully develop even in its natural habitat of temperate regions. Hence, the cultivation of the species on a commercial scale is not attractive to farmers.

    D.floribunda Mart. And Gal. (2n=36)
    It is a native of Mexico (Central America) and is grown in Karnataka, Goa, Assam, Meghalaya and the Andaman Islands. This species can be very easily propagated from tuber pieces and seeds. The plant is dioecious in nature, a robust climber twining to the left. The branches are thick and it produces yellow, compact tubers at a shallow depth. The leaves are petiolate and spirally disposed on the stem. The male flowers are solitary or in groups of 2-3, dark-brown or green and sessile with 6 stamens. The male spike is short and solitary, with 6 staminodes and a hypogymous stigma with a bifid apex (divided into two). The diosgenin content varies from 2-7% depending upon the age of the tubers. The seeds germinate within 3-4 weeks and produce vigorous seedlings that establish well in the field.
    Three varieties of D. floribunda have been released for cultivation. The varieties FBC-1 strain and Arka Upkar were released from the Indian Institute of Horticultural Research (IIHR), Bangalore, while Pusa-1 by the Indian Agricultural Research Institute (ICAR), New Delhi. These three varieties adapt well to tropical and subtropical regions. The salient features of these varieties are as follows.
    FB (C)-1
    This is a composite strain from introduced clonal material from Central America. The plants are vigorous and relatively free from pests and diseases. The tuber yield is 20 000-25 000 kg/yr (1 kg/plant) or 60 000 kg for a 2-year-old crop (2.5 kg/plant). The diosgenin content of the dried roots varies from 2.5 to 3%.
    Arka Upkar
    A high yielding clonal selection from FB(C)-1 with intense dark-green leaves and a vigorous growth. The tuber yield exceeds 6000 kg (in a 2-year-old crop) and the diosegenin content ranges from 3.5 to 4.0%.
    Pusa-1
    A selection from germplasm with a tuber yield of 1.5 kg/vine after 18 months.

    D composita Hemsl.
    This species is also a native of Mexico and has been domesticated in several tropical countries. It is a robust climber, twining to the left, which produce large, thick leaves. The underground portion comprises of thick, fleshy, branching tubers which are long, white in colour and grows deep. This species is mostly propagated from seeds rather than from tubers, as the rotting of tubers is pronounced.
    Other important sapogenin-bearing species are D.friedrichshali R.Kunth, D.spiculiflora Hemsl, and D.prazeri. Prain and Burk.

Last modified: Tuesday, 3 April 2012, 8:59 AM