Biology and Planting of Pineapple

Pineapple (Ananas comosus) is a perennial crop with monocotyledonous plant having a terminal inflorescence and a terminal multiple fruit. It continues to grow after fruiting by means of one or more axillary buds growing into vegetative branches with a new apical meristem. These branches come to maturity and produce fruit while still attached to the old plant, through which they obtain most of their nourishment. Adult pineapple plants are about 1 m tall and 0.5 m wide. The main morphological structures of the plant are the stem, the leaves, the peduncle (stem which bears fruit), the multiple fruit or syncarp or sorosis, the crown, the shoots and the adventitious roots. The peduncle and inflorescence develop from the apical meristem. The stage of inflorescence emergence is called 'red heart' because of the 5-7 reddish peduncle bracts at its base. The inflorescence consists of 50-200 individual flowers, capped by a crown composed of numerous short leaves (up to 150) on a short stem. The flowers of the pineapple open in the sequence of their origin, starting with the whorl of flowers at the base of the inflorescence.

Commercial propagation of pineapple is not through seeds but by the use of vegetative shoots including the crown, slips, and suckers and occasionally shoots induced from the dissected stem of mature plant and less frequently by tissue culture of meristem. Crowns, slips, suckers and stem sections have all been commonly utilised for vegetative multiplication of the pineapple. The definition of vegetatively propagable parts and their locations are as follows: slips are leafy branches attached below the fruit, on the peduncle, grouped near the base of the fruit, sometimes produced from basal eye of the fruit commonly preferred, may produce fruit within 14-16 months after planting. Ground (ratoon) suckers are shoots produced at or below ground from the stem and, when used, will produce fruit in 12-14 months after planting. Side shoots are shoots produced from the above ground portion of the stem, when used, will produce fruit in 18-20 months after planting. Crown is the short stem and leaves growing from the apex of the fruit and is not commonly used because it may take up to 24 months after planting to produce fruit.

 

 

The crown slips and suckers are capable of forming a new plant . All these structures can survive detached from the parent plant for up to 6 months depending on the prevailing conditions. Although pineapples can be grown from seed, fertility in commercially grown cultivars of pineapple is very low and consequently seed production is very rare. More than 3 months are necessary from flowering to fruit maturity. The entire pineapple blossom develops parthenocarpically (development of fruit without fertilisation) into a berry-like fruitlet. The edible part of the fruit consists mainly of the ovaries, of the bases of sepals and bracts and of the cortex of the axis. The fruit shell is mainly composed of sepal and bract tissues and the apices of the ovaries. Pineapple flowering is uneven and it is highly desirable to attain uniform maturity and to control the time of harvest in order to avoid overproduction in the peak periods. In order to do this flower induction technique using induction hormones are used. Several different types of hormone can be used like Calcium carbide, Naphthalene acetic acid (NAA), Planofix and Ethrel. Flower induction is carried out one month after fertilizer application.

 

 

The best time is in the morning or in the evening where the temperature is lower. Growth hormone is implemented to improve fruit development and growth. An example of growth hormone used is Fruitone. This process is conducted 80 to 110 days after flower induction. Fruit mature 152 days after the date of flower induction or when the brectia changes colour from reddish to pale and the fruitlet change from reddish to blackish brown. Harvesting of fruits can be done semi-mechanised or manually by plucking each matured fruit and collected into large baskets. For certain variety subject to 'sun burn' or scorching, a plastic cap are placed at the crown area to protect fruit from direct sunlight (See photo next). This is to ensure estimated 10 - 15% fruit are damaged during the high temperature especially on peat area. Wasallam!.

By,
M Anem,
Senior Agronomist,
Kelompok Nenas Parit Bulat,
Muar, Johor,
Malaysia.
(January 2014)