Pummelo Production
Pummelo (Citrus maxima), Suha or Lukban is one of the most
popular specie of the Citrus family. It has a long shelf
life that it can be transported to distant markets.
The pummelo tree grows from 5-15 meters in height and has
low spreading branches with a canopy size ranging from
500-900 centimeters. Its leaves are ovate to oblong with
leaf size ranging from 5 cm x 12 cm to 8 cm x 20 cm wide
when fully expanded.
The flowers are located either in the axial or terminal
point, raceme type of inflorescence and fruit is yellowish
green in color, nearly round to pear-shaped. It matures
five to six months after flowering. The juice vesicles are
either white, light pink or red, depending on the variety.
Seeds are few to nil ridged, deltoid to globous in shape
and mono embryonic.
Uses
The fresh juicy pulp vesicles are eaten fresh out of the
hand or in the fruit salad and sometimes the juice is
extracted for beverage.
The white inner part of the peel can be candied after the
outer peel containing oil glands have been removed.
In Vietnam, the aromatic flowers are used in making
perfumes.
The wood is used for tool handles and firewood while
leaves, flowers, fruits and seeds are sometime used as
herbal medicine to treat cough, fevers and gastric
disorders.
Properties
The edible segments form only a small fraction of the
thick-skinned fruit. A 100g edible portion is composed of
the following:
Water (g) 89.00
Protein (g) 0.50
Fat (g) 0.40
Carbohydrates (g) 9.30
Vitamin A (IU) 49.00
Vitamin B1 (mg) 0.07
Vitamin B2 (mg) 0.02
Niacin (mg) 0.40
Vitamin C (mg) 44.00
Recommended Pummelo Cultivars
Magallanes
Origin Davao City
Yield (No of fruits /tree 227.00
Weight of fruit (g) 859.03
Edible portion (%) 44.20
Total soluble solids (%) 9.00
Flesh color Pink
Amoy
Origin Canton, China
Mantan Yield (No of fruits /tree 203.00
Weight of fruit (g) 814.83
Edible portion (%) 52.85
Total soluble solids (%) 9.22
Flesh color Pink
Siamese
Origin Thailand
Yield (No of fruits /tree 252.00
Weight of fruit (g) 1050.91
Edible portion (%) 51.07
Total soluble solids (%) 9.41
Flesh color White
Dela Cruz Pinl
Origin Lubongan, Toril, Davao City
Yield (No of fruits /tree 347.00
Weight of fruit (g) 784.76
Edible portion (%) 57.57
Total soluble solids (%) 9.67
Flesh color Pink
Soil and Climatic Requirements
1. Soil Requirement
Adapted to a wide range of soil types provided, they are
reasonably deep, well-drained and aerated with high
moisture retention.
Optimum pH range from 5.5-6.5.
Liming to increase pH when it is below 5 (acidic).
Water logged soils, sticky heavy soils, wet soils and
those underlain with hardpan should not be used.
2. Climatic Requirement
Grows in lowland tropics in elevation up to 400 meters
above sea level with optimum temperatures of 23-300C.
Optimum light requirement of 32.3-86.1 klux
Annual rainfall requirement of 1500-1800 millimeters.
Production of Seedlings for Rootstocks:
Select fully developed seeds from mature/ripe fruits of
Calamandarin (believed to be
a hybrid of calamondin and mandarin)
Seeds should be selected from fruit trees that are free
from Citrus Canker
(Xanthomanas Citri) to avoid contamination on the seed.
Fruit that dropped or fall on the ground should not be
picked up and use as seedlings
for rootstock.
Disinfect the seeds with CHLOROX at 5% solution, rinsed
with tap water and air dry
before sowing.
Seed beds (nursery) should be isolated from existing
citrus orchard to prevent
possible contamination through insect vectors.
Soil media should be light type (sandy loam) and free
from any soil borne insect pests
like root grubs and nematodes.
Sterilize the soil media.
Extracted seeds should be sown immediately to avoid
drying.
Care of Seedlings for Rootstock
Water the seedbed to facilitate germination.
When seeds started to germinate, exposed the seedbed to
sunlight. Do not put
shades. Shades provide a microclimate which favors the
growth of dumping-off
pathogen. Seedlings that grow without shades are hardy and
free from dumping-off
disease.
Seedlings do not need too much water. Too much water on
poor drained beds
predisposes the seedlings to dumping-off disease.
Spray chemicals to protect young seedlings from pests
and diseases.
Recommended minimum dosage should be used to prevent
leaf burn.
Potting and Transplanting of Seedlings
Seedlings are ready for potting 21-28 days after
germination in "7 x 12" x .003
polyethylene plastic bags containing garden soil and place
them in the nursery.
Avoid transplanting seedlings with deformed root system
(goose-neck root)
Calamandarin seeds are polyembryonic thus from 1 seed,
2-3 seedlings germinate. One of the seedlings that
germinate is an off-type. This seedlings are characterized
by
their stunted growth, weak and the leaves produced are
smaller that other seedlings. These seedlings should be
eliminated.
Water immediately the newly potted plants.
Fertilize the seedlings when signs of new shoots or
growth have developed.
Asexual Propagation and Care of Budded Seedlings
Rootstocks are ready for budding in 6-8 months; or at
least pencil-sized in stem
diameter.
Apply nitrogenous fertilizer at 5-10 grams per plant 2-3
weeks before budding.
A round bud-stick give more good buds that angular
bud-stick.
Budding should be done at a height of 6-8 inches above the
ground level.
Do not fertilize newly budded plants; unless the bud eye
have shown signs of growth.
Remove the wrap of bud 3 weeks after budding.
To hasten growth of bud-eyes, "lopping" or "cripping"
the top of the seedlings 2-3
inches above the bud is recommended.
When bud-eyes started to germinate; decapitate the
rootstock 1-3 inches above the
bud-eye union to force the growth of the bud-eye or scion.
Weeding should not be done when the scion are succulent
and tender, thus are
susceptible to breakage when touch.
Budded plants are ready for planting at 8 months old.
Orchard Establishment
Land Preparation
Clear/remove all stumps and grasses
Plow twice and harrow thrice to loosen the soil.
If the soil is acidic, incorporate dolomite lime during
plowing and harrowing
Get soil sample for analysis.
Field Layout and Distance of Planting
The field layout should be either square or quincunx
method depending on the
topography of the orchard.
Distance of Planting
10 m x 10 m = 100 seedlings/hectare
8 m x 10 m = 125 seedlings/hectare
6 m x 8 m = 208 seedlings/hectare
8 m x 8 m = 156 seedlings/hectare
Preparation of Holes and Planting
Dig a cubical hole measuring 50 cm. Wide and 50 cm deep.
The hole will be filled up
with a mixture of 50% decomposed measure, 50% top soil and
2 tablespoon of
nematicide.
Remove the plastic bag and plant the seedling into the
prepared hole without breaking
the ball of soil. Prune the roots to enhance root
branching.
Plant young plants at their dormant stage.
Cover the hole with the soil-manure and press gently.
Plant during the rainy season.
Care of the newly planted seedlings
Water the plants immediately after planting to assure
close contact between soil and
roots and prevent wilting.
Apply fertilizer when the newly planted trees started to
developed new growth.
Weed control - weeds compete with the seedlings for
nutrients, sunlight and water.
Mulching the trees with grasses, rice straw, rice hull
and banana pseudostem will
conserve soil moisture during dry period, prevent the
growth of weeds and as source
of organic matter after decomposition.
Wounds on the bark and branches should always be painted
with water repellant
paints.
Plowing and planting of intercrops should be 1-2 meters
away from the rows or hills of
the trees to avoid injury on the trunk, branches and roots
Prune the young pummelo tree and leave three main
framework branches. The lowest
branch should be 40-60 cm. off the ground.
Care and management of non-bearing and bearing trees:
Weeding. Weeds compete with the seedlings for nutrients,
sunlight and water. Weeds
must therefore be removed regularly or as the need arises.
Avoid covercrops to
creep around the base of the tree.
Mulching. Mulching prevents the growth of weeds, and
help conserve soil moisture and
serve as source of organic matter when decomposed.
During rainy season, however, mulch should not be placed
to close to the tree
because it is conducive to fungus.
Intercropping. Intercropping is done to maximize land
use. Banana (lakatan,
latundan) intercrop can serve as windbreak, shade and
source of early income.
Irrigation. For sustained fruit production, it is
important to water the pummelo before
flowering and until after harvest to supplement rain.
Pummelo plants are moisture sensitive during flushes of
new growth, flowering, fruit
setting, and fruit enlargement. As a practical guide for
irrigation, watering should be
done when 20-30 cm of the top soil is dry.A matured
pummelo requires 100-200 liters
of water per day especially during flowering, fruit
setting and enlargement to a month
before harvest.
Pruning. Diseased and non-productive branches and water
sprout using bolo, pruning
shear or pruning saw must be pruned. All pruned surface
must be painted to minimize
entrance of micro-organisms and enhance healing. It is
preferably done after
harvesting.
Fertilizer Application and Management
1. Soil and Tissue Analysis
Soil and tissue should be collected and analyzed to
determine the amount of fertilizer that will be applied.
It is the most reliable way to determine the fertilizer
requirements of pummelo.
Concentration of minerals found in branches, leaves and
fruits of pummelo.
Elements Plant Parts
Fruits Leaves Branches
Nitrogen 2.0% 2.6% 1.2%
Phosphorous 0.2% 0.18% 0.17%
Potassium 2.0% 1.00% 0.75%
Calcium 0.8% 4.2% 1.8%
Magnesium 0.15% 0.25% 0.28%
2. Kinds of fertilizer
a.) Organic fertilizer
Fertilizer materials that came from living things. It can
be animal manures or decomposed plant and animal bodies.
This fertilizer material can:
Improve soil structure and non-toxic to the root
Improve soil aeration that encourage root elongation.
Contain less nutrients
b) Inorganic fertilizer
materials from weathered rocks plus the nitrogen coming
from the atmosphere.
granular from that contain on inert material called
carrier.
It contributes 80% I the soil mass
Crop response in noticeable after a week
Less bulky and easy to apply but expensive
Makes the soil acidic, especially N fertilizers
Toxic to the roots if applied in very high rates
3. Time of Fertilizer
Application:
Apply fertilizer when there is
a sign of shoot growth.
The recommended fertilizer levels should be applied in
2-3 installments; at the onset
of rainy season, middle of rainy season, and towards the
end of the rainy season
Fertilizer are applied by digging holes around the tree
within the area covered by the
canopy.
Fertilizers applied should be covered with soil to
minimize surface evaporation and to
prevent soil erosion.
Maximum efficient utilization of fertilizer was found in
20-30 cm deep and 100-150 cm
from the trunk of matured pummelo trees.
Foliar fertilizer can be applied to supplement the soil
applied fertilizers.
It was found that Potassium applied on foliage increases
fruit size and sugar content
of the fruit.
Foliar fertilizer are applied at 40 days after fruit set
(DAFS); 60 DAFS; and 90 DAFS
4. Nutrient Deficiency Symptoms
1. Nitrogen (N)
retards enzymatic activities and vegetative growth
Yellowing of foliage
Twig die-back
2. Phosphorus (P)
Retard fruit development
leaf and fruit abscission
rough fruits
thicker rind
3. Potassium (K)
small fruit size
immature fruit splitting (rind disorder)
low sugar and acid content
4. Calcium (Ca)
Breaking of branch
short shelf life of fruits
5. Magnesium (Mg)
yellowing of foliage
reduce photosynthesis (low yield)
6. Zinc (Zinc)
Smaller leaves
chlorotic leaf spot
twig die-back
small size of fruits
7. Manganese and Iron (Mn and Fe)
Small size leaves
yellow color of leaves
low fruit setting
small size fruits
Harvesting
Pummelo trees bear fruit 3-5 years from planting and can
be harvested after 5-6
months flowering.
Change in color - (green to yellow with 50% color
change)
Acid ratio is 10:1 with 9% Total Soluble Solids.
Oil glands in the skin becomes more prominent and shiny.
Juice content of 50% be weight
Harvest pummelo fruits either by pulling or clipping
from the fruiting branches
The best time to harvest is around 8:00 am to 3:00 pm
(with sunlight) to reduce fruit
injuries on the peel of pummelo.
Do not harvest pummelo fruits when the rind are still
wet dry it before packaging.
Post harvest Handling and Management
Sorting. After harvest, the fruits must be brought to a
shaded area. Sort the fruits
according to size, color, and rind quality. Discard fruits
that are injured, bruised, and
misshapen.
Packaging. The fruits must be placed in kaing or wooden
crates lined with newspaper
or other suitable materials to prevent abrasions and
punctures. Size of the containers
depend upon the transportation system available
Storing. For longer shelf life, pummelo fruits can be
stored for 12-14 weeks at a
temperature of 120C and 85-90% relative humidity. Under
ambient conditions, the
fruits have a shelf life of 5-14 days.
Post-harvest treatment. For longer storage life, it is
recommended to dip the fruits in
thiabenzadole, benomyl or 2 amino butane at the rate of
500-1000 ppm. This will
sustantially prevent the spread of post-harvest diseases
and reduce losses.
Pests and Diseases and their Control
A. Insect Pests
1. Rind borer (Prays endolemma)
Plant Part Damage: Newly opened flowers and young fruits.
Control Measures: Apply pre and post bloom sprays with the
use of either Cymbush, Gusathion, Decis at recommended
dosage; Collect and burn or bury infested fruits.
2. Scale Insects
a. Snow scale ((Pinnaspis sp)
Plant Part damage: Trunks and twigs
Control Measures: Apply Dimethoate and oil-based materials
b. Black scale (Saissetia kemisphaerica)
Plant Part Damage: Trunks, twigs, and leaves
Control Measures: Spray malathion and recommended dosage.
3. Mites
Plant Parts Damage: Leaves and fruits
Control Measures: Spray Dicarzol, Kelthane, Malathion,
Dimethoate
B. Bacterial and Fungal Disease
1. Citrus canker (Xanthomonas citri)
Symptoms: Lesion on both sides of the leaf and fruit
ridges on the fruit
Transmission: Contaminated budwood, man, animals, tools,
and wind
Management:: Burn severely infected trees or eradication;
Spray any copper-based fungicide
2. Foot Rot (Phytophtora sp) Gummosis
Symptoms: Sap oozing from small cracks on the bark;
lesions spread around the trunk
Management:: Use resistant rootstock; avoid deep planting;
water management; aeration around the crown; surgical
treatment; treat with copper-based fungicide
3. Pink Disease (Corticium salmonicolor)
Symptoms: White fan-shaped coating of mycelia growth
becomes pink; Bark is destroyed, girdled and die
Management: Remove affected barks of trunks and prune
diseased parts; disinfect by spraying copper fungicide or
lime sulfur mixture
4. Fruit Rot (Diplodia natalens)
Management: Burn rotten fruits to prevent spread of the
spores
5. Scab (Sphaceloma faucetti)
Symptoms: Disease starts as small, pale orange, circular
spots on young fruits. As disease advances and fruits
start to mature, several lesions coalesce and form
irregularly shaped spots.
Management: Spray copper fungicides at the time when new
flushes of growth appear or at time of blooming when
two-thirds of petals have fallen. Successive sprays may
follow two weeks thereafter up to the time when fruits are
half matured.
C. Virus and Virus-like Diseases
1. Greening/Leafing mottling
Causal Organism: Fastidious bacteria
Carrier: Diplodia citri (Jumping plant lice)
Integrated Disease Management:
Eradicate infected plants
Use disease-free planting materials
Shoot tip grafting
Health indexing and spraying of insecticides (Dimethoate)
on citrus trees at shooting stage
Biological control of psyllid vector (Octoparasites)
2. Triztesa (Virus)
Symptoms: Stem pitting
Most varieties of citrus are affected by stem pitting
disease which develop large number of pits on trunks and
stems
Carrier: Brown citrus aphids (Toxoptera citricidus)
Black citrus aphids (Toxoptera aurantii)
Melon aphid (Aphis gossipii)
Integrated Disease Management:
Use of resistant rootstocks
Mother trees where scions are obtained should be
periodically examined and indexed
3. Exocortis (viroid)
Symptoms: Yellow stem blotches and dark splits; die-back;
stunting; reduced yield
Carrier: Infected budwood, nursery tools
Integrated Disease management:
Selection and indexing test of non-infected budwood
Use of healthy budwood
Use shoot tip grafting to eliminate the pathogen
Disinfect tools used for budding and pruning with
household chlorox.
4. Xyloporosis (viroid like)
Symptoms: Mild wood pitting to advance bark scaling; wood
disorganization and impregnation of affected tissues with
gums
Carrier: Infected budwood, nursery tools, and contaminated
equipments
Integrated Disease management:
Selection and indexing test of non-infected budwood
Use of healthy budwood
Disinfect tools used for budding and pruning with
household chlorox.
5. Psorosis (complex of viruses)
Symptoms: Chlorotic blotching in young and mature leaves;
bark scaling of branches and trunks
Carrier: Infected budwood
Integrated Disease management:
Use of indexed budwood and seeds free of psorosis
Scions should be cut only from indexed trees known to be
free from Taller leaf virus
6. Tatter leaf virus
Symptoms: Stunted growth
Carrier: Infected budwood and sap transmissible
Integrated Disease Management:
Infected materials can be made virus-free by combination
of heat treatment and shoot tip grafting (STG)
References:
CARRDEC Techno-Series, May 2005
Loquias, VL. And RT. Serapio. 1998. Technology advances in
the commercial production of pummelo. A paper presented
during the on-site techno-demo training on the cultural
management of high value fruits. Naomi's Botanical Garden,
Banadero, Ozamis City. April 2-3, 1998. 24 pp.
Plant resources of South-East Asia. 1992. Edible fruits
and nuts. E. W. M. Verheij and R. E. Coronel (Editors).
Prosea Foundation. Bogor, Indonesia. 444 pp. |