Thursday

Recommended seedbed and nursery management techniques


Coconut nurseries around the world
Here is a short movie on coconut nursery pracices around the world, with special emphasis to the Pacific region and two other countries for comparison.



The best technique, allowing regularly to obtain high germination rate, seems the one presently used in Côte d’Ivoire. In this country, the CNRA Agricultural Centre benefits for a sandy soil allowing to partially bury the seeds, to water them regularly and to efficiently control their hydration. Thus, for other countries, a solution could be delimiting the seedbed space with a concrete border, bringing one or two trucks of sea sand, and filling the seedbed with a sand thickness of about 20 cm. Coconut was made to grow on sea sand...


Nursery site selection

A good nursery should:
  1. be open, level and well-drained;
  2. have light or loose-textured soil to facilitate nursery operations;
  3. have a good source of water without possibility of being flooded;
  4. be accessible to transportation; and
  5. be far from existing potential sources of coconut insect pests and diseases, e.g. sawmills, pile of decaying logs, dump site of animal manure, etc.
To be fully operational, the nursery should have a fence for security; a shed to house the implements and supplies; farm implements and small equipment; a source of water for irrigation; and sufficiently trained manpower. A nursery site with a minimum area of 3,600 m2 is needed to accommodate about 12,000 seednuts 
for 50 ha of plantation per year. It is preferable to locate the nursery in the centre of the plantation when applicable.

The seedbed

The seedbed should preferably located in the centre of the nursery. To facilitate sowing of nuts, it should be cleared, plowed and harrowed to a fine tilth. Seedbeds are prepared with the following dimensions:
  • elevation: 10‑20 cm high to provide drainage
  • width: 1 m to avoid stepping on seednuts during maintenance and transfer operations
  • length: a 2 m long seedbed is ideal for easy inspection, management and maintenance
  • pathway: 1 m between seedbeds should be provided to facilitate inspection, selection, pricking, maintenance and seedling transfer activities.
Notching of the nuts facilitates the emergence of the germ and allows a better moistening of the flock and a better rate of germination. The husk is notched on the side of the floral pieces on the widest and flatest hump, using a sharp machete. The surface of the cut must be close to that of a small orange cut in half. A too deep cut causes a weak link between the nut and the plant, with the risk of ruptures in the collar during planting.

Nuts are planted by firmly setting them either upright or slightly tilted with the germ end at the top. The nuts are set close to one another to prevent them from floating in case of heavy rains. The nuts are then covered with soil, with about 2/3 of their size buried. In addition to keeping a record file, a signboard, placed in front of each bed, provides the following information:
  • Name of variety/ type
  • Date when nuts have been harvested, if available
  • Date of sowing
  • Number of nuts sown
  • Seedbed number
Seedbed maintenance involves daily watering except when it is raining; weeding, if necessary; partial shading, when needed (dry coconut leaves can be used to provide partial shading, as done in Samoa, but the results are not as good as other shadinh techniques); and inspection for disease and pest incidence.

The seedling must receive homogeneously 4 to 5 mm of water per day, 4 to 5 liters per m2. The duration of the watering depends on the flow of the installation, the ideal being to bring the desired water quantity in about one hour. We control the degree of humidification by pressing with the thumb the notch of the nuts, a drop of water must appear.

Seednuts should be removed from the seedbed and transferred in another part of the nursery when the sprout emerges through the husk to a height of 4-6 cm. To make an efficient choice, it is indispensable to pick out the germinated nuts before the shoots reach 20 cm in height. If the nuts remain in the seed bed too long, the young plants will become stringy due to over-crowding and nursery selection will become difficult.

Field or polybag nurseries?

There are two types of nurseries for rearing coconut seedlings: polybag nursery and field nursery. A polybag nursery makes use of black polyethylene bags, hence its name.

Clearly, the best is Polybag nursery, because: a) transplanting shock is greatly minimized, thereby promoting early establishment of transplanted seedlings; b) seedlings can be retained longer in the nursery when conditions for field planting are not yet favourable; and c) age-wise, seedling selection is easily accomplished. Anyway, seedlings in bags are more expensive (cost of the bag), and more  difficult to carry in the fields for plantation.
When using polybags, the selection in the nursery is more efficient, the coconut palms will start to produce at least 6 monthes before, and less palms will dye at the young age.

Field nursery
Field nursery seedlings should be planted immediately or at the latest 3 days after removal from the nursery to reduce mortality. Before transplanting, each hole should be applied with fertilizers mixed with soil. Alternatively or in addition, a small amount of organic matter, e.g. seaweeds, husks or any other compost materials, can be placed at the bottom of the hole and covered with soil leaving about one‑third free for the seedling nut to 'sit'.


Polybag nursery
When the sprout emerges through the husk to a height of 4-6 cm, seedlings are planted in the field nursery either directly in the soil or in polybags, to allow them more space to grow. At this stage, some roots, already out of the husk, might have been injured in the process of pricking. It is therefore necessary to trim them before transferring in the field or polybag nursery. The trimming of these roots assists the seedling to establish quickly as it will induce the seedling to produce more roots. Seedlings of the same age are pricked on the same day and immediately planted in the field or polybag nursery. It is very important that pricking is done only when the field or polybag nursery is already prepared. Pricking can be scheduled once a week.

A polybag, preferably black, UV resistant for durability and measuring 40 x 40 x 0.015 cm (for smaller nuts) or 45 x 45 x 0.015 cm (for bigger nuts) with 8 - 10 holes at the bottom sides, is half filled with soil and compost mixed at 50:50 ratio. Decomposed sawdust, corn cobs, rice hull and other organic materials can be used. This will reduce the weight of the half-filled polybag and improve soil fertility. If polybags are not gussetted (Note: polybags with folds at the bottom may be ordered), the bottom corners should be folded inward to make the bottom of the bag round and for it to stand firmly. The open edge of the bag is also folded back (about 3 cm) to prevent it from tearing easily. The germinated nut is then placed in the half-filled bag with the sprout in an upright position in the centre of the bag. Next, the bag is filled with soil with the sides slightly pressed to keep the nut firm until it is fully covered. As the soil settles, it will cover up to 2/3 of the nut after some time. When the polybagged seedlings are ready, they are laid out in the polybag nursery.

Equal setting of the seedlings at optimum distance dows them to grow and develop normally. The technique follows a. triangular system with equal spacing of 60 em. Set the polybagged seedlings in the same order as they germinated. The earliest germinating seedlings are placed in the first row in the eastern side of the area. The last ones to germinate are placed at the western section of the area. This practice reduces competition for sunlight from among the earliest and latest germinating seedlings. Most importantly, selection of vigorous seedlings is facilitated and since the first pricked seedlings are placed in rows, culling or judging by age is easily accomplished. A signboard indicating the type/variety, the number of seedlings and date of sowing is installed in front of each plot.

Maintenance of the polybagged nursery involves watering, weeding, and inspection for pest and disease incidence. The water requirements of the nursery are about 200 mm per month. If it does not rain, watering must ensure all the needs. A flow rate of 10 m3 per hour per hectare of nursery should be planned. Except in case of organic management, fertilizer application for each seedling is recommended as follows:


Age after germination
(months)
Ammonium sulphate
(NH4)2 SO4

21-0-0
(g)

Potassium chloride
(KCI)

0-0-60
(g)
OR
Sodium chloride
(NaCI)


(g)
2
20
25

20
5
40
45

40

The fertilizers are mixed and applied directly to the soil around the nuts. Afterwards, the soil is lightly cultivated to promote faster dissolution and absorption of the fertilizer.

At 6-8 months of bagged nursery, a coconut plant is at the best stage for planting under the best conditions (well developed root system and reduced planting shock); At this age, the youngest leaves are already differentiated into leaflets. The following criteria apply for Dwarf x Tall hybrid plant:
  • Collar circumference: 18-20 cm;
  • Number of living leaves : 7 to 8;
  • Height = 110 to 120 cm according to the types (from the base of the plant to the tip of the first leaf).
However, in countries where rainfall limits the planting season, to use the seed garden’s production capacity to the fullest extent, plants between 5 and 12 months could be pricked out.

Laying out of the polybag nursery (staking)

The size of a polybag nursery could be 3 x 6 m with about 1.5 m spaces between plots. Each plot will easily accommodate 115 seedlings. While only 72-96 palms will be used, extra seedlings might be needed for future use as replacements.
Equal setting of the seedlings at optimum distance dows them to grow and develop normally. The technique follows a. triangular system with equal spacing of 60 em. The materials needed are the following:
  • about 30 m of rope or twine for establishing a straight line and making a 3,4,5 triangle
  • 100 pieces bamboo pegs or equivalent, 30 cm long
  • a measuring tape or stick
  • twine for marking 30-cm spaces, about 10 m long
  • pieces of stick, 52 cm long
  • a sharp bolo, machete or its equivalent
  • compass
  • marking pen.
Figures hereunder shows how these materials are to be used to attain a 60-cm spacing in a triangular manner. To minimize shading, rows should be oriented in a North-South direction.

Figure from Stantech manual
As a start, about 10 m of twine (preferably cotton) is marked every 30 cm along its entire length. First, establish a straight line and a 90º corner with the longer side towards the North. This is done easily by making a 3,4,5 triangle using the 30 m rope. Boundaries are set by means of rope or twine to guide the setting of rows. This is made to establish four straight boundary lines and four 90º corners.
Figure from Stantech manual
The next step is to lay the 10 m string in the direction of the North and then mark the 30 cm spaces. This becomes line 1 or row 1. To make line 2 or row 2, measure 52 cm down towards the East (or West) in both ends of row 1. Then align the string marked every 30 cm and subsequently peg the 30 cm marks. Repeat the procedure to make rows 3,4,5, etc. To establish 60 cm, remove the pegs every other 30 cm starting from the second mark in line 2. These are marked (x) in Figure 12. As the work progresses, and as the workers gain experience, the marks are pegged every 60 cm by estimation.



The size of a polybag nursery could be 3 x 6 m with about 1.5 m spaces between plots. Each plot will easily accommodate 115 seedlings. While only 72-96 palms will be used, extra seedlings might be needed for future use as replacements.




















References

Stantech manual