SINGLE STAGE POLY BAG NURSERY AND SECONDARY NURSERY

       The germinated seeds can be directly planted into large black polybags with the advantage of avoiding the pre-nursery stage. At present the single stage polybag nursery is recommended in India. Since the plants are to remain in these polybags for more than one year, good quality polybags of 500 gauge and 40 x 45 cm size are to be used. On the lower half of the bag, perforations are made at an interval of 7.5 cm for drainage. A bag can carry 15 - 18 kg of nursery soil depending on the type of soil mixture used.

       The water requirement for different stages of growth of seedlings are as follows: 0 - 2 months at 4 mm/day, 2 - 4 months at 5 mm/day, 4 - 6 months at 7 mm/day and 6 - 8 months at 10 mm/day. It is better to supply if feasible the daily requirement in two halves to prevent overflow and wastage caused by one time application. Application of 9 - 18 lit. of water per seedling per week according to the stage of growth and soil type.

NURSERY AND ITS MANAGEMENT

       Nursery is raised by planting germinated sprouts initially in a pre-nursery bed or in polybags in a primary nursery and transplanting them at five leaf stage to a secondary nursery of large sized polybags. Raising seedlings in large polybags without a pre-nursery stage is also being practiced.

     The potting mixture is made by mixing top soil, sand and well decomposed cattle manure in equal proportions. Smaller polybags of 250 guage and 23 x 13 cm size, preferably black are used for raising primary nurseries. These bags are filled with the potting mixture leaving one cm at the top of the bag. A healthy germinated sprout is placed at the centre at 2.5 cm depth. While placing the sprout, care must be taken to keep the plumule of the sprout facing upwards and the radicle downwards in the soil. It is better to plant sprouts soon after the differentiation of radicle and plumule. The seedlings are to be watered daily. Application of a fertilizer mixture containing one part of ammonium sulphate, one part of super phosphate, one part of muriate of potash and two parts of magnesium sulphate is recommended at 15 g at one month stage, 45 g at three months stage and 60 g at six months stage per seedling. This has to be applied 6 - 8 cm away from seedlings during the first application, 10-12 cm away during second and 15-20 cm away during the third application in primary nursery. Surface soil is slightly scratched at the time of fertilizer application.

WATER REQUIREMENT

          Continuous soil moisture availability encourages vigorous growth and increased yield of oil palm. Adequate supply of water, good soil depth and water holding capacity contribute to water availability. In oil palm as water deficiency increases, stomata will remain closed and the development and opening of spear will be inhibited. Water deficiency adversely affects flower initiation, sex differentiation and therefore, results in low sex ratio due to production of more male inflorescences. It is established that oil palm needs 120 - 150 mm of water to meet its monthly evapo-transpiration needs. In areas where perennial water source is available, basin irrigation is possible.

       But where the terrain is undulating and water is scarce during summer months, drip irrigation is recommended to keep four drippers per palm in the weeded palm circle to supply atleast 90 litres of water per palm per day during summer months which will vary according to the ETP values in a locality.

FREQUENCY OF HARVESTING

      Harvesting rounds should be made as frequent as possible to avoid over ripening of bunches. A bunch which is almost ripe but not ready for harvest for a particular harvesting round should not be over-ripe by next round. In lean period of production, harvesting can be made less frequent and it should be more frequent in peak periods. Harvesting rounds of 7 - 14 days are generally practiced. Other factors determining frequency are, extraction capacity of the mill, transportation facilities, labour availability and skill of the workers. In India, harvesting is usually carried out with a chisel of 6 - 9 cm wide attached to a wooden pole or light hollow aluminium pipe, Bunches are cut without damaging the petiole the leaf that supports it. Use of narrow chisel is usually carried out till the palm reaches two meters above the ground. For taller palms upto 4 meters, a wider chisel of 14 cm is used. The curved knife is attached to a long bamboo or aluminium pole with screws or steel wires to harvest from taller palms. In uneven stands, an adjustable, telescopic type of pole is in use.

HARVESTING

        Proper and timely harvesting of fruit bunches is an important operation which determines the quality of oil to a great extent. The yield is expressed as fresh fruit bunches (FFB) in kg per hectare per year or as oil per hectare per year. The bunches usually ripen in six months after anthesis. Unripe fruits contain high water and carbohydrate and very little oil. As the fruit ripens oil content increase to 80 - 85% in mesocarp. Over ripe fruit contains more free fatty acids (FFA) due to decomposition and thus increases the acidity. Usually the ripe fruits, attached to the bunches contain 0.2 to 0.9% FFA and when it comes out of extraction plant the FFA content is above 3%.Ripeness of the fruit is determined by the degree of detachment of the fruit from bunches, change in colour and change in texture of the fruit. Ripening of fruits start from top downwards, nigrescens fruits turning reddish orange and the virescens (green) to reddish brown. Fruits also get detached from tip downward in 11 - 20 days time. Ripeness is faster in young palms than in older palms for the bunches of equal weight. The criteria used in determining the degree of ripeness based on the fruit detachment are as follows:

a)	fallen fruits: 10 detached or easily removable fruits for young palms and 5 for adult palms,
b)	number of fruits detached after the bunch is cut; 5 or more fruits/kg of bunch weight,
c)	quantity of detachment per bunch; fruit detachment on 25% of visible surface of bunch.

These criteria could be applied with flexibility.

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Insect pollination in oil palm

       The oil palm, hitherto though to be wind pollinated, has been now proved to be an a insect pollinated species. From West Africa, the original home of oil palm, eight species of pollinating weevils were reported. Occurence of Eldeidobius kamerunicus in the oil palm plantations of Kerala was introduced during 1985 from where it was introduced and got established in little Andamans during 1986.

         The weevils are dark brown in colour. Adult weevils feed on the anther filament. Eggs are deposited inside the male flowers and larva feeds on the spent flowers. Life-cycle is completed within 11 to 13 days. Males live longer than females. The activity of the insects is in accordance with the receptivity of the male and female inflorescences. It was roughly estimated that 40 palms in a grove might be the minimum to sustain a sufficiently high continuous population of pollinators to pollinate. All are receptive female inflorescences. The weevils carry maximum pollen during the third day of antheses. Antennae, rostrum, thorax, legs etc. are the main sites of pollen land. E.kamerunicushas a fairly good searching ability. It can survive in dry as well as in wet seasons.

         Introduction of weevil in India increased the fruit let from 36.8 percent to 56.1 percent resulting in 40 per cent increase in F/B ratio. The maximum attainable pollination potential was as much as to cent percent with 57 percent increase in FFB weight.

         For introduction, male flowers cut from palms which have the weevils are transferred to a plantation where one wishes to introduce. In order to make sure that they are not carrying any plant pathogens to other area/countries, we have to breed them under laboratory conditions for seven or eight generations before introduction.

PRUNING OF LEAVES

          In oil palm two leaves are produced per month. Therefore, it becomes necessary to prune excess leaves so as to gain access to bunches for harvest. Severe pruning will adversely affect both growth and yield of palm, cause abortion of female flowers and also reduce the size of the leaves. It was suggested that palms aged 4 - 7 years should retain 6 - 7 leaves per spiral (48 - 56), those aged 8 - 14 years 5 - 6 leaves per spiral (40 - 49) and those above 15 years should have 4 - 5 leaves per spiral (32 - 40). Leaf pruning is carried out in India using chisels so that leaf base that is retained on the palm is as short as possible or otherwise it may catch loose fruits, allow growth of epiphytes and the leaf axils form a potential site for pathogens. The leaf petioles are removed by giving a clear cut at a sufficient distance from the base of the petiole using a sharp chisel for young palms and with the long sickle in taller palms.

         Pruning is preferably carried out at the end of the rainy season. It is also better to carry it out during the low crop season when labourers are also available. Pruning is confined to only lower senile leaves during initial harvests but when canopy closes in later years, leaves are cut so as to retain two whorls of fronds below the ripe bunch.