Agriculture Reference
In-Depth Information
in importance as fresh fruit varieties and now dominate international trade.
Other varieties of some importance commercially include 'Queen' and
'Spanish', both of which are primarily consumed fresh.
CULTURAL PRACTICES
Planting material and propagation
Propagules used in commercial pineapple production include fruit tops
(crowns), shoots borne on vestigial fruits at the base of the fruit (slips) and
shoots borne at any position on the stem (suckers) (Fig. 12.5). Genetic
variation in numbers of slips produced per plant exists between clones
and cultivars. Two or three crowns can be produced as a result of high-
temperature injury during early infl orescence development, but large numbers
of crowns (multiple) or fasciation of crowns is considered a genetic defect and
such plants typically are rogued. Types and sources of vegetative propagules
are kept separate, because weight, nutritional history and development
environment are believed to af ect time to establishment and optimum plant
size for fruiting, as well as having the potential to introduce variability into
the fi eld (Hepton, 2003). Time from planting to harvest is dependent primarily
on the weight of the propagule, and crowns produce fruit in 18-24 months,
slips in 15-20 months and suckers in 12-17 months. Planting materials are
treated with a fungicide or are 'air-cured' by drying the butt end, or both,
before planting to prevent rots.
A shortage of planting material can occur when fruits are sold fresh,
because the fruit is usually marketed with the crown. Most commercial clones
of 'Smooth Cayenne' produce only one to two suckers per plant and seldom
more than three slips. Several techniques are available to speed up propagule
production required for variety and clone development or to replace planting
material sold with the fruit. Cost of labour often determines which techniques
are used.
Stem sectioning utilizes the axillary buds, usually on stems of mature
plants. Leaves are stripped of the stem; the stem is quartered longitudinally
and each quarter is divided into sections approximately 5 cm in length. The
sections are immersed in a fungicide solution or air-cured for several days, or
both, before planting in well-prepared nursery beds with good drainage and
aeration. Shoots that grow from axillary buds can usually be transplanted in
4-6 months. A normal-sized 'Smooth Cayenne' plant stem can produce an
average of 25 sectioned plants (Collins, 1960). Established crowns and shoots
with adequate root systems can be split longitudinally into quarters, which
forces one to several axillary buds to develop. These small plants (plantlets)
can be transplanted when large enough and the process repeated. A similar
technique is to gouge out the plant's apical meristem, thereby breaking apical
 
Search WWH ::




Custom Search