Propagation

• Clonal seeds : Collected from approved seed gardens in the country and abroad.
• Budded plants: Either poly bag or root trainer plants can be used for planting.

Nursery preparation

 Bud wood nursery

• Bud wood nursery is raised by planting polybag plants or budded stumps of authentic planting materials of desired clones at a spacing of 90 x 60 cm.
• Before planting, bud wood nurseries are given a basal dose 165 kg of powdered rock phosphate per hectare (1.65 kg/100 m 2 ).
• Two to three months after planting, 125 g of 10-10-4-1.5 NPKMg mixture/ plant is applied.
• A second application at the same rate is given 8 to 9 months after planting.
• This dose should also be applied 2-3 months after each harvest of bud wood.
• The first harvest of brown bud wood is done one year after planting by cutting the shoot 30 cm above the bud union.
• Two sprouts are allowed to grow for the second harvest after similar growth.
• This process of cutting back each healthy shoot is to be repeated every year to allow regeneration of fresh bud wood.
• Green bud shoots are generated by cutting back the growing shoots in a bud wood nursery 6 to 8 weeks before bud grafting.

 Polybag and root trainer nurseries

• Polybag and root trainer grown plants grow well when maintained in poly houses. This is particularly useful for green/young budded plants.
• Reduction in disease incidence and increased growth is observed in poly houses.
• Prevention of excess sunlight using shade nets and appropriate ventilation to avoid heat and humidity build up are necessary for healthy growth of plants.
• Regular but controlled watering and manuring are essential.

 Rubber nursery

• Nurseries are maintained for raising seedlings, budded plants and bud wood.
• As rubber seed viability is very short, seeds are collected for planting soon after fruit dehision.
• Germination beds are prepared with the top 5cm made up of river sand or well leached coir pith.
• The beds should be raised 10-15 cm above ground to avoid water logging and be of 90 cm width and convenient length.
• Partial shading may be provided to protect from strong sunlight.
• Seeds are sown closely in single layer and pressed firmly into the sand leaving the surface of seeds just visible above the sand.
• Seeds sprouted on each day should be picked into a vessel containing water to avoid injury.
• The picked seeds should be planted in seedling nursery without any delay

 Seedling nursery

• Level lands with water table at least 60 cm below is ideal for raising seedling nursery.
• Shaded areas should be avoided.
• Soil should be deep, well drained loam with good fertility status.
• Raised beds (15 cm) should be prepared with width of 60 to 120 cm and convenient length with pathways in between to facilitate cultural operations.
• The spacing adopted for planting in seedling nurseries are 23 x 23 cm (for green budding) and 30 x 30 cm (for brown budding).
• Application of a pre-emergent herbicide Diuron at the rate of 2.5 kg in 700 litres of water per effective hectare if applied after preparation of beds prevent weed grown for 6 to 7 weeks.
• Manual weeding should be done at monthly intervals.
• Mulching in between the plant rows reduces weed growth besides conserving soil moisture and regulating soil temperature.
• Addition of 25 kg of compost or dried FYM is also recommended

Planting materials

 Stumps

• Seedling stumps are prepared by pulling out polyclonal seedlings and cutting back the stem at 45 to 60 cm of brown wood, tap root to convenient length and trimming of lateral roots (7.5 cm length).
• The cut end of stem is dipped in molten wax to prevent water loss.
• Budded stumps are prepared in the same way as seedling stumps but a slanting cut with slope towards opposite side of bud is gen at about 7.5 cm above the bud patch.

 Polybag plants

• Polybag plants are raised either by budding seedlings that are developed by in situ planting of seeds (in polybags) or by planting budded stumps in polybags.
• Polythene (LDPE/HDPE) bags of 45 x 18 cm holding about 7 kg soil are generally used.
• Larger bags 55 x 25 cm which holds about 10 kg soil are preferred for raising larger plants (3 whorls or more).
• The polythene material used for the bag should be 75-100 micron thickness (300- 400 gauge).
• The bags should be filled with top soil.
• About 20 to 25 g rock phosphate is incorporated in the top half of the soil filled in the polybags.
• Monthly application of the fertilizer 10:10:4:1.5 NPK Mg mixtures at 10g/plant initially, gradually increasing up to 30 g/plant, when each top whorl of leaf is mature is recommended
• Regular watering and weeding is necessary.
• Partial shading (50% shade) during dry season reduces incidence of leaf spot diseases and sun scorch besides regulating transpiration loss.
• Plants are transplanted to the main field when they are at two to three whorl stages and the top whorl of leaves is mature.

 Root trainer plants

• The root trainer cups usually have a length of 26 cm and a holding capacity of 600 cc with vertical ridges on the inside wall and tapering with a drainage hole at the bottom.
• Well cured coir pith (washing with water at least for two months to leach out all toxic compounds) mixed with neem cake, bone meal, pesticides and single super phosphate is used as potting medium.
• Partially dried elephant dung mixed with equal quantity of soil can also be used as an alternative to coir pith.
• The potting medium should be packed well inside the root trainer cup before planting seeds.
• Root trainers are stacked in a raised bed of soil so as to facilitate tap root development.
• When the plants show healthy growth, the root trainer is lifted from the bed

Planting

• Spacing

  • The density of planting recommended is 420-520 plants per hectare (170 to 200/acre).
  • However, for the clone RRII 105 the density can be up to 550/ha.

• Lining

  • In flat or slightly undulating areas, square or rectangular planting can be adopted.
  • For rectangular planting, lines should be taken east-west to get maximum sunlight.
  • Contour lining is done on undulating and hilly lands by marking out the planting points in contour line across the slope.

• Soil and water conservation

  • Formation of terraces is a recommended practice in hilly areas to conserve soil and water.
  • In order to reduce erosion further and to facilitate rain water infiltration trenches of about 1cm
  • length, 45 cm width and 60 cm depth are taken along with contour in between the planting rows.
  • Construction of stone-pitched contour retaining walls (edakayyalas) is another effective method to restrict surface runoff.

• Drainage

  • Proper drainage is essential especially on low-lying lands.
  • The natural waterways existing in the plantation may be cleared or deepened to give adequate drainage.
  • If drains are cut, uniform depth should be maintained throughout.

• Pitting

  • Pits are taken either manually or mechanically using tractor-mounted hole diggers or earth mover.
  • The texture and depth determine the size of the pit.
  • In soils with a depth of one meter or more, planting can be done in small pits dug to accommodate polybag plants.
  • However in hard soils, planting should be done in larger pits of size 75 cm3 or 90 cm3 depending on hardness.
  • While digging the pit, the top soil should be placed on one side and subsoil on the other.
  • Filling should be done with top soil after removing stones and roots.
  • Compost or well rotted cattle manure @ 12 kg and rock phosphate 200 g are mixed with the top 20 cm soil in the pit.
  • When small pits are taken, the manure should be incorporated around the plant basin leaving around 15 cm from bud union.
  • In newly-cleared forest areas, 200 g rock phosphate alone would suffice.

Field planting

• Seed-at-stake

  • Two to three germinated seeds are directly planted in the centre of the refilled pit.
  • After establishment, the most rigorous one is retained which is field-budded subsequently.

• Seedling and budded stumps

  • Planting of seedling and budded stumps should be done immediately after pulling out.
  • While planting budded stumps, the bud patch should be just above the ground level to reduce the effect of elephant foot and infection by soil-borne pathogens.
  • A hole with depth equal to the length of tap root is made at the centre of the pit.
  • After levelling the soil, the stump is placed in the hole with its tap root and lateral roots spread out in proper position so that the tip of the root is in contact with bottom soil and no air gap is left in between.
  • The hole is then filled and the soil around the stump is packed firmly with the help of a crowbar.

• Root trainer plants

  • At the time of planting, the root plug can be separated from the container without any damage by inverting it and giving a gentle tap of the rim of the root trainer on any hard surface.
  • A planting hole can be made in the refilled planting pit by pressing the empty root trainer container into soil.
  • The root plug is carefully inserted into the planting hole and the soil around is compacted.
  • The root trainer plants show early establishment due to its well-developed root system.