Ananas comosus, commonly known as pineapple, is an herbaceous perennial belonging to the order Bromeliales, family Bromelaceace and sub-family Bromelioideae [1-3]. According to Carlier et al. [4] there are 56 genera of the pineapple which include 2921 species. According to Gene Technology Regulation [5] and Carr [6], pineapples originated in South America and through travels and migration of different peoples, its cultivation spread to other parts of the world. The Jamaican pineapple is said to have been discovered by Christopher Columbus on his voyage to the New World in the 15th century.
Bartholomew et al. [1], in describing the pineapple, states that the plant grows to 1-2 m high and wide with a club shaped stem having dimensions of 25-50 cm in length, width of 2-5 cm at the base and 5-8 cm at the top. The leaves are sessile and enclose the stem on two thirds of its circumference. They tend to be sword like with sharply dentate edges often variegated or
streaked red-brown. The roots are found only in young seedlings and die soon after germination at which time they are replaced by adventitious roots. The peduncle and inflorescence develop from apical meristems. The flowers of the pineapple are bluishpurple with the oldest leaves at the base of the inflorescence [6].
Pineapples are able to thrive in Jamaica because of the favorable environmental conditions. Naturland [7] reported that the plant prefers warm and stable temperatures between 65°F–79°F and grows best when planted at heights below 700 m. The preferred soil type for planting is sandy loam which helps to facilitate good drainage. Pineapple plants grow best in acidic soils, pH of 4.5-6.5. Essential nutrients in the soil for growth of pineapples include nitrogen, iron, sulphur, magnesium and phosphorous. Though the plant can tolerate low soil fertility, the best production is in fertile soils as outlined in Table 1 [1].
There are approximately seven cultivars of the pineapples which are in fact clones due to vegetative production of the crop [1,3]. Second to bananas, pineapple contributes more than twenty percent of the world production of tropical fruits. Approximately seventy percent of this global production is consumed as fresh fruit [3,8,9]. Based on the Ministry of Agriculture Jamaica Newsletter, Market wise [10], the three preferred market varieties in Jamaica are Sugar loaf, Cowboy and Ripley. In 2009, the Food and Agricultural Organization reported that the island produced a total of approximately 21368 tonnes of pineapple (Food and Agriculture Organization [11]). This was produced primarily using traditional cultivation practices.
Traditionally, pineapples are propagated asexually from crowns, slips, hapas and suckers. For commercial purposes, propagation is mainly done by crowns and slips [1,3,6]. Slips develop from buds in axils of leaves, grow upwards and are curved at the base. They are usually harvested 2-5 months after crop harvest which equates to 10-13 months after slip growth. Slips are broken from the peduncle, dried and planted within one month of harvest [1,6]. Cultivation by the crown is by far less complicated. It involves removing the crown from the harvested fruit, allowing it to dry for at least 2 weeks after which it is replanted. When compared to slips, crowns grow at a slower rate and are less resistant to drought [1,3,6,11]. The turn over time for new propagules when using either method is approximately 18 months which is a slow route for commercial purposes.
An alternative to traditional methods of propagation is tissue culture. Tissue culture maybe used as an additional method of propagation to supplement traditional methods.
The tissue culture process can be summarized in four stages; initiation, multiplication, rooting and acclimatization [12,13]. The initiation stage involves selecting the mother plant and surface sterilization of the explant. Under a sterile environment, the explant is placed on nutrient medium with the aim of establishing the plant in culture. The next stage is multiplication, and as the term suggests, this involves proliferation and multiplication of shoot. This stage is normally repeated until the desired numbers of plantlets are achieved. Rooting stage prepares the propagated plants for planting out into soil. The plantlets are often transferred to rooting medium which serves the purpose of inducting root formation. The final stage in the tissue culture process is acclimatization. This is where the plants are transferred from culture medium to the soil and acclimatized to the external conditions. The plants are kept in a shade or green house where they become adapted to the external environment by modifications to leaf morphology and anatomy [2,3].
As statistics from the Ministry of Agriculture suggests, the fruit is economically important to the island. Market wise [10] has stated that locally, the fruit is consumed for its sweet taste as well as its nutritional and health benefits. Pineapples are an excellent source of vitamin C, manganese and are said to possess anti-inflammatory properties. Due to the importance of the pineapple to the Jamaican economy it has proven to be a viable investment option. However, using only traditional methods may not prove to be lucrative due to the long turn over period.
This study was therefore designed to assess the effectiveness of utilizing tissue culture techniques to produce pineapple plants and compare their productivity, nutritional profile and maturations period with those grown using traditional cultivation practices [14].
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