Port Blair, Apr 27: Globally, root and tuber crops are the third important food crops of humankind after cereals and grain legumes and constitute either staple or subsidiary food for about a fifth of the world population. These crops have a remarkable position in the food security due to its high calorific value and carbohydrate content. Apart from supplying cheap source of energy, these crops provide other micronutrients and vitamins. These crops have a higher biological efficiency as food producers and also the highest dry matter production per unit area. Their capacity to grow under rain fed conditions as well as sustainability against the drought condition is remarkable. Great flexibility in planting and harvesting are the important characters of these crops which are aptly suitable to include in any farming systems. Thus, the tuber crops are very important in the context of food and nutrition security since in majority of the tuber crops, the roots, tubers and leaves are edible. Leaves of some of the tuber crops are highly nutritious like other green vegetables.
The commonly cultivated tropical tuber crops in Andaman & Nicobar Islands are: Cassava (Manihot esculenta), Sweet potato (Ipomoea batatas), Elephant foot yam (Amorphophallus paeoniifolius), Taro (Colocasia esculenta), Tannia (Xanthosoma sagittifolium) and Greater yam (Dioscorea alata).
Due to the recent unavoidable lock down situation and restrictions imposed thereon and also due to the prolonged drought situation in the Islands, the farmers are compelled to stay at home leaving all farm activities. Since for most of the tuber crops, the planting season is April- May before the onset of South- West monsoon, it is the right time to prepare the land and take up the planting of tuber crops.
In general for production of different tuber crops, use of organically produced planting material, seed treatment with cow dung, neem cake, bio-inoculant slurry, farmyard manure inoculated with bio-inocluants, green manuring, and application of neem cake, bio-fertilizers and ash are recommended.
Soil physical condition influences the plant growth and hence proper tillage is required for the successful cultivation of tuber crops. Loosening the soil to a depth of 20-25 cm either by tractor ploughing or spade digging facilitate better rooting.
Cassava:
It is recommended to incorporate crop residues of the previous crop dry biomass @ 3 t ha-1, planting setts of 15-20 cm from disease free cassava stems with a spacing of 90 x 90 cm, application of FYM @ 12.5 t ha-1 (1 kg per plant) at the time of planting along with the application of Azospirillum, phosphobacteria and K solubilizer @ 3 kg ha-1 each at the time of planting.
Elephant foot yam
Pits of 60 x 60 x 45 cm are dug at a spacing of 90 x 90 cm and the pits may be filled with 3 kg of FYM and topsoil. Seed treatment of corm pieces of 500 g with slurry containing cowdung, neem cake and Trichoderma harziannum (5 g per kg seed) and drying under shade before planting, application of Trichoderma harziannum incorporated FYM @ 36 t ha-1 or 3 kg per pit at the time of planting (FYM: neem cake mixture (10: 1) inoculated with Trichoderma harziannum @ 2.5 kg per tonne of FYM neem cake mixtute. Trichoderma can be multiplied to form sufficient inoculam quickly within 7-8 days if neem cake is also used along with FYM. Apply neem cake @ 1 t ha-1 or 80-85 g per pit at the time of planting.
Greater Yam
The field must be prepared by ploughing 3-4 times. Pits of the size 45 x 45 x 45 cm may be prepared at spacing of 1 x 1m and the pits are filled with FYM @ 1.2 kg/pit or 15 tonnes/ha and mixed with the topsoil, then mounds or ridges are formed. Treat cut tubers pieces of 250- 300 g size in cow dung slurry and plant at the centre of the mounds at a depth of 30-40cm. Application of neem cake @ 1 t ha-1 or 80-85 g per pit and bio fertilizers viz Azospirillum @ 3 kg ha-1, mycorrhiza @ 5 kg ha-1 and phosphobacteria @ 3 kg ha-1 at the time of planting is recommended.
Taro
Seed treatment of cormels (20-25 g size) with slurry containing cow dung, neem cake and Pseudomonas (5 g per kg seed) and dry under shade before planting, planting the cormels in ridges and furrows with a spacing of 60 x 45 cm, application of FYM @ 15 t ha-1 (400 g per plant in pits), neem cake @ 1 t ha-1 or 25-30 g per pit and application of bio fertilizers viz Azospirillum @ 3 kg ha-1, mycorrhiza @ 5 kg ha-1 and phosphobacteria @ 3 kg ha-1 at the time of planting is recommended.
Tannia
Pits of 60 x 60x 45 cm are dug at a spacing of 90 x 90 cm and the pits may be filled with 3-4 kg of FYM and topsoil. Planting of whole cormels of size 50-80 g or mother corm pieces of 150-200 g, application of FYM @ 20 t ha-1 (1.6 kg per plant in pits) and neem cake @ 1 t ha-1 or 80-85 g per pit at the time of planting is recommended.
In general, immediately after planting, mulching the pits with dried leaves or crop residues are recommended for early sprouting and better growth and development by conservation of moisture and suppressing the weed growth. It is also recommended for sowing of green manure cowpea (20 kg ha-1) between the inter row and the subsequent incorporation of green matter at 45- 60 days of after sowing. In addition, application of ash @ 2 t ha-1 at the time of incorporation of green manure in pits is recommended.
