Thursday, 28 September 2017

Recommended seedbed and nursery management techniques

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.

How many seednuts to plant one hectare?

Taking into account:
  • the germination percentage (80% is the international standard exept for Aromatic Green Dwarf (60%)
  • eliminations at the seed bed stage (12 %), (abnormal, latest germination, Dwarfs when planting DwarfxTall hybrids)
  • selection in the nursery (15%)
  • the fact that about 5% of the palms need to be replaced during the first and second year after planting
The following table gives the quantity of seednuts to prepare according to the type of varieties planted. Selection is an essential stage and only the strict application of the rules described in these guidelines can guarantee the greatest precocity an highest profitability to the plantation. As planting a young a coconut represents an investment in more than 30 years of exploitation, it is better to conduct severe elimination in the seddbed and nursery rather than to keep on from 10 to 20 p. 100 of backward, stunted, unproductive or barely productive trees throughout the plantation’s life.

Types of
coconut
varieties
Number of palms for one hectare
Number of palms for replacement
Ungermi-nated 20%
Eliminated
in seedbed 12%
Eliminated in the nursery 15%
Number
of seednuts
needed
Tall and Tall x Tall hybrids
143
7
50
24
26
251
Dwarf x Tall hybrids
160
8
56
27
30
280
Dwarfs, compacts dwarfs and  D x D hybrids
180
9
63
30
33
316
Dwarf x Tall hybrids - Brazilian way
180
9
63
30
33
316
Dwarf compacts dwarfs and  D x D hybrids - Brazilian way
222
11
78
37
41
390


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.

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.

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'.





















References

Stantech manual

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