Pineapple growing

  • Published on 30/10/2013 - Published by Cirad
  • FruiTrop n°215 , Page From 66 to 68
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Summary

The pineapple, Ananas comosus, a member of the Bromeliaceae family, originated in South America. The cultivated pineapple still has several traits of this parentage:

  • · its root system is extremely fragile and the plant prefers light, well-tilled soil;
  • · it tolerates very dry spells by strongly reducing growth but still surviving;
  • · the base of the leaves is the most efficient zone for uptake of nutrients and it responds well to foliar fertilisation;
  • · flowering is induced by low temperatures and short days and is erratic under natural conditions. This gives rise to the most remarkable feature of cultivation—flowering induced artificially by a cropping operation.

Growers can thus—almost at their wish—control harvest date and yield, as fruit weight depends on the size of the plant at the moment at which flowering is induced artificially. Fruit quality is determined essentially by sugar content and acidity, and varies considerably according to weather conditions and the fertilisation applied. In simple terms, nitrogen nutrition determines weight and potassium nutrition determines quality. It is an extremely heterogeneous compound fruit whose base is always at a later stage of development than the upper part. Pineapple is not climacteric and after harvesting the main change in the fruit is a gradual loss of its qualities. This deterioration must therefore be limited in the fresh fruit packing and transport chain—fast transport and sales with no breaks in the cold chain. When the fruit is processed, this must be performed as quickly as possible.

Cycle of the plant

The pineapple exhibits three main phases:

  • ·  the vegetative phase from planting to the differentiation of the inflorescence (flowering);
  • ·  the fruiting phase running from differentiation to harvesting of the fruits;
  • ·  the sucker growth phase: from fruit harvesting to the destruction of the plant.

The parts of an adult pineapple plant are as follows:

  • ·  stalk: a short club-shaped stem that contains starch reserves and has a fibrous structure that makes mechanical destruction difficult;
  • ·  leaves: with a maximum of 70 to 80, these can be more than 1 m long and 7 cm broad. Their appearance indicates the state of health of the plant and growth vigour;
  • ·  fruit: a compound fruit that is the equivalent of a fused, compressed bunch. Its weight depends on plant size at floral induction and the nutritional state of the plant at that stage. It is determined first of all by the number of eyes;
  • ·  crown: a leafy part topping the fruit;
  • ·  roots: underground and above-ground. The underground roots are fragile and the slightest discontinuity of the soil profile strongly disturbs growth. The roots are put out in the first month after planting. They then just lengthen and no new root emission takes place before the fourth or fifth month;
  • ·  shoots: these are of two types—slips that grow on the stalk beneath the fruit, and true shoots that grow at the leaf insertion point on the stalk.

Ethephon  

Ethephon is widely used around the world on flower, grain and fruit crops. France alone has no less than 24 registered uses in fruit growth, flowering and maturation processes.

Ethephon is registered for two specific uses in pineapple growing: for triggering the flowering process (floral induction treatment) and the regulation of fruit ripening (degreening). In both cases, the ethylene released by the product acts on physiological mechanisms.

Pineapple possesses the feature of being able to flower on demand, and floral induction is generally performed using gaseous ethylene dissolved in water. As application is a big operation, the process is generally used only on mechanised plantations. Another method used on non-mechanised smallholdings is calcium carbide. However, this is somewhat dangerous as the acetylene gas released is inflammable and even explosive if it comes into contact with copper.

The product that is easiest to use is Ethephon, even though it is less effective on varieties such as 'Smooth Cayenne' and MD-2, more popularly known as 'Sweet'.

Cultivation

  • ·  Soil: alluvial or volcanic at an elevation of less than 600 metres. Deep soil. Good drainage. Gentle slopes (less than 4%). As 'Sweet' is susceptible to Phytophthora (a fungal disease), the ideal soil pH range is 5.0 to 6.5.
  • ·  Plants: 50 000 to 70 000 plants per hectare. The quality of planting stock is of fundamental importance: genetically pure 'Sweet' stock with no defects (spines, diseases, etc.), of uniform size (calibrated in 100 g categories), propagules must be as heavy as possible to shorten the cultivation period (but not too heavy as natural flowering should be avoided) and treated with registered pesticides to prevent the spread of pests and diseases.
  • ·  Post-harvest: 'Sweet' is susceptible to bruising.
  • ·  Nutrition: fertiliser is applied by spraying every two weeks. The fertilisation programme starts after the harvest.
  • ·  Weeds: these can reduce yields and harbour pests and diseases that attack planted fields if they are not eradicated in time.

 

Controlling flowering

When the plant reaches the appropriate stage of development it becomes sensitive to climatic factors and meteorological factors (day-length, decrease of minimum temperature and cloud cover) that determine the differentiation of the inflorescence. Natural flowering then occurs that is not compatible with the commercial management of a plantation. Floral induction treatment (FIT) consists of changing the natural cycle of the plant for the following purposes:

  • · homogenisation of flowering;
  • · control of production;
  • · control of average fruit weight;
  • · harvest planning.

The date of FIT is determined according to:

  • · the harvest date desired;
  • · the FIT/harvest date interval for the period (historical or calculated from the sums of temperatures);
  • · plant weight (a good indicator being the weight of leaf 'D') that determines that of the fruit.

Three floral induction substances are used:

  • · acetylene in calcium carbide form: grains are placed in the centre of the floral rosette or mixed with water to make an acetylene solution;
  • · ethylene gas: less dangerous than acetylene, treatment with an ethylene solution can be mechanised;
  • · ethephon (Ethrel®): this is an ethylene generator. It is much easier to use than the first two alternatives but the results are often mediocre, especially in very hot conditions.

Degreening treatment

This is performed by application of Ethrel and is to achieve homogeneous fruit colour and reduce the number of picking operations. Ethrel releases ethylene as it breaks down. It does not have an effect on all maturation phenomena but mainly targets colour. It must be applied fairly close to natural fruit maturity in order to be effective with no major disadvantages. Fruits treated in this way are easy to recognise as their colour is not scaled from bottom to top but uniform throughout the shell.

Protection from sun scald

This seasonal phenomenon occurs above all during very sunny periods. Fruits that have lodged, whose stalks are too long or that have a deficient leaf system are those most exposed to sun scald. Several protective methods can be used: tying the leaves in a bunch over the fruit or the whole crop ridge, mulching with grass, or lifting up lodged fruits.

 

  • Ananas

    Ananas

  • Ananas.

    Ananas.

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