Agriculture Reference
In-Depth Information
clementine in 2009 were Spain, China, Turkey, Morocco,
and Pakistan, whereas the Russian Federation, Germany,
France, the United Kingdom, and the Netherlands were the
top five importers.
harvest management practices vary from region to region.
The control of insects, pests, and pathological diseases
is of significant importance. The citrus group fruits are
susceptible to intense fog and rain-fed conditions, which
severely affect the fruit set and its maturity, resulting in low
yields.
Similar to other citrus group fruits, tangerine, mandarin,
and clementine can also be affected by many pests which
not only reduce vigor and yield of the fruits but also act
as vectors of potential viral and bacterial diseases. The
following pests are economically detrimental to the cit-
rus crop: aphids, mites, citrus leaf-miner, citrus butterfly,
snow scales, fruit sucking moth, and mealybug. The fruit
flies usually attack the citrus, damaging their outer sur-
face, causing fruit rot. Some borers and larvae of beetles
attack the roots and branches that may lead to tree decline.
Among the pests there are nematodes (
Citrus nematode
)
and microscopic vermiform organisms, and some of them
are parasites in nature. Some fungal and bacterial pathogens
also attack the plant and fruit, thus resulting in fruit drop
and tree decline. The disorders include phytophtora induced
diseases, blast and blade pit, postharvest fungal diseases,
tristezia, ring-spot psoriasis complex, blight, and so on.
There are some recommendations regarding the adaptation
of certain chemical compounds aimed at reducing the phys-
iological and morphological aberrations in the fruit. These
include spraying of auxins and gibberellins to improve the
yield and produce quality. Additionally, some other chem-
icals are also applied, for example, fungicides and insecti-
cides to minimize the preharvest decay of fruit (Zhang and
Timmer, 2007).
For harvesting, the most common methods include the
snap method and clipping method. The snap method, being
the primitive technique, involves twisting the fruit stalk
while detaching it from the parent tree. However, clip-
ping/cutting has gained immense attention owing to de-
creased losses associated with its use. There is a need in
developing countries to adopt mechanized harvesting meth-
ods to minimize these losses.
Burns (2004) noted that high-quality mandarins/
tangerines typically have a turgid, deep orange-red peel
relatively free of any blemishes. The fruit should be el-
liptical in shape and firm to touch. The peel should be
easily removed from the flesh; the edible portion should be
juicy. Burns (2004) further reported that maturity standards
require that mandarins have a set minimum sugar-to-acid
ratio and have at least 50% peel surface color break. For
shipping and storage, mandarins are packed in 4/5 bushel
cartons, and the size of marketable mandarins ranges from
size 56 (56 fruit/carton) to size 210 (210 fruit/carton).
PRODUCTION PRACTICES, PREHARVEST
MANAGEMENT, AND HARVEST
The fruit part of the citrus is modified berries/matured
ovary, botanically termed as hesperidia. Moreover, the
leaves and flower parts are also important as they contain
oil sacs at leaf blades and petiole region, respectively. The
fruits are usually spherical or ellipsoid in nature, depend-
ing on the species profile and varieties cultivated. The fruit
can be divided into two main parts, that is, rind/peel and
edible parts. Moreover, rind and peel have two distinct lay-
ers, including flavedo (external layer) and albedo (internal
white layer). The edible part of citrus fruit contains locules
covered by slightly thick layer of vascular bundles. On the
interior of the membranes, a large number of juice vesi-
cles are present, each containing juice within the vacuoles
(Goldschmidt, 1988).
The fruit set rely on many factors, including genetics,
environment, and cultural practices. However, production
of reasonable amount of hormones in ovaries is necessary
for fruit bearing until maturity. Pigmentations may also
occur in some species owing to their anthocyanin contents.
The ratio of total soluble solids and acidity is one of the
major determinants of fruit quality, not only in the fresh
citrus fruit but its processed products as well.
There are some other factors that need to be addressed
to improve the quality of final produce. In this context,
selection of soil and climate is very important; soils with
pH values of 5.4-8.0 are normally more suitable with lower
water holding capacity. The site and soil should be rich in
micronutrients (Calabrese, 2002).
Cultural practices, such as plant spacing, tillage opera-
tions, herbicides, and indeed cultivation of covered crops
in some citrus species, are gaining popularity. Addition-
ally, the irrigation is important for the sustainability of
citrus species as they are evergreen in nature. The water
requirement varies depending on the climate and soil type
as sandy soil requires more irrigation as compared to clay or
loamy soils (Fadda et al., 2006). Last, controlling the num-
ber of productive branches is also important and manual,
and mechanical pruning is employed to reduce the number
of branches, thus improving the yield.
Preharvest management and harvesting
The tangerine, mandarin, and clementine are cultivated in
different geographical zones of the world, and thereby pre-
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