Planting material
Tapioca is propagated by stem cuttings. Select mature healthy stems free from diseases or pests. Discard about 10 cm from the lower mature and about 30 cm from the upper immature end. Stems should be cut into setts of 15-20 cm length using a sharp knife. About 2000 stems are required for planting one hectare. Harvested stems are to be stored vertically in shaded and well-aerated places. Spraying dimethoate (0.05%) on the stem will control scale insects.
Season
The main planting seasons are April-May with the onset of southwest monsoon and September-October with the onset of north-east monsoon. Planting can also be done during February-April, provided sufficient moisture is made available through irrigation. For maximum tuber production, April-May planting is preferred because the crop can effectively utilize both the monsoons. The second best season is September-October.
Minisett planting technique for quality planting material
For producing minisetts, mature, disease free stems preferably those obtained from indexed meristem culture should be selected. Two node cuttings are taken from these stems using a sharp hack-saw. Top one-third portion is usually discarded in the traditional system, however in the minisett technique, it is fully utilized. The tip of the stem (about 5 to 6 cm long) is carefully cut without causing damage. For preventing dehydration, it is advisable to place the tip cuttings in water. The stem just below the growing tip is very tender with prominent axillary buds. Hence, from this portion, cuttings with four nodes are taken instead of two as the latter may easily get dried up.
Preparation of nursery:
Select an area with well drained soil and irrigation facility. Shade net house of 35 per cent shade is ideal for the germination and growth of minisetts. Mark out the length and breadth and make raised beds of soil : sand mixture in equal proportion. The beds could be of convenient length and width not exceeding 1 m. An area of 220 m2 nursery is required for producing minisetts for planting one hectare of land. Two node cuttings are planted end to end horizontally, about 5 cm deep inside the soil, with the buds facing either sides. Tip cuttings and four node top setts should be planted erect at 5 cm x 5 cm spacing to prevent decay due to excess moisture in these tender parts. Minisetts would sprout in a week’s time. Mosaic virus infected plants, if any found, should be rogued off as soon as such symptoms are expressed, to keep the nursery disease free. The minisetts will be ready for transplanting in about three to four weeks time. After the basal application of recommended manure in the main field, ridges of 30 cm height are taken with a spacing of 45cm between the ridges and planting is done on the ridges at a spacing of 45 cm. Multiplication ratio by this process is enhanced to 1: 60 as against the traditional method 1:10.
Land preparation and Planting
Before planting, plough the field 2-3 times or dig to a depth 25-30 cm depending upon soil type to establish a deep porous field in which the setts are to be planted. Pit, flat, ridge or mound method of planting can be adopted depending upon soil type, topography of land and elevation so that waterlogging is avoided. Pit followed by mound is found to be the best method of planting. Plant the cuttings vertically after smoothening the lower cut end, at a depth not exceeding 4-6 cm. Adopt square method of planting at a spacing of 90 x 90 cm @ one cutting per pit. It is preferable to adopt 75 x 75 cm spacing for non-branching varieties like M-4.