Pongamia pinnata locally known as Karanja is a medium sized evergreen tree planted for shade and as ornamental tree in the greater part of the country. It is a drought resistant salt tolerant, nitrogen fixing leguminous tree and to some extent tolerant to slight frost. The seeds are largely exploited for extraction of a non-edible oil, commercially known as “Karanja Oil” well recognized for its medicinal properties and also used in the manufacture of soap. Leaves are used as fodder and green manure. The wood of this tree is used as fuel throughout the country and also used for construction, tool handles and agricultural implements.
This brochure is a part of the extension series being brought out by the Indian Council of Forestry Research and Education for the use by farmers, foresters and the common man.
KNOWING THE SPECIES
Pongamia Pinnata (L.) Pierre (syn. Pongamia glabra vent.) belongs to the family Fabaceae (Papilionaceae).
This is a medium-sized evergreen tree with a spreading crown and a short bole. The tree is planted or shade and is grown as ornamental tree throughout the greater part of India. It is found in many parts of India. This tree grows widely in the littoral forests of Sundarbans and Andamans and also along river-banks in the Peninsular India. It is also cultivated along roadsides, canal banks and open farm lands.
Pongamia pinnata is a moderate-sized evergreen tree. Bark smooth, grey, thin. Leaves imparipinnate; leaflets opposite, stipellate, 5 to 9 in number, ovate to ovate-elliptic, shortly acuminate, glabrous, bright green. Petiole 4.5cm long. Inflorescene of axillary racemes, shorter than leaves, about 20cm long. Flowers 1cm across, xygomorphic. Calyx campanu-late. Corolla purplish-white; petals-5. Stamens 10, monadelphous, the upper stamen free at the base, connate from middle to closed tube. Ovary subsessile, 1 to 2 ovulate; style incurved. Pods obliquely oblong, 4 x 3cm, woody, compressed, indehiscent. The chromosome number of this species (2n) is 20, 22.
Pongamia starts flowering from the 4th or 5th year of planting. White and purplish flowers in axillary racemes appear in April to July and the pods ripen from February to May in the following year.
II. UTILIZATION OF THE SPECIES
a). As a Plantation Tree
Pongamia pinnata is a drought resistant, nitrogen-fixing leguminous tree. It is also salt tolerant and to some extent tolerant to slight frost. It is a good shade tree. The shade provided by this tree is said to have cooling effect and is good for health.
The seeds are largely exploited for extraction of a non-edible oil, commercially know as “Karanja oil”, which is well recognized for its medicinal properties. The yield of fruit varies from 9 to 90 kg per free for different age trees. There is no systematic and organized collection of seeds. Mature seeds consist of 95% kernel and are reported to contain about 27.0% oil. The yield of oil is reported to be about 24.0 to 26.5% if mechanical expellers are used for the recovery of oil from the kernels, but it is only 18 to 22% from village crushers. The estimated potential of the seeds is about 1.11 lakh tons per year and that of oil is about 0.29 lakh tons and the oil produced is about 0.08 lakh tons. The crude oil is yellow orange to brown in colour which deepens on standing. It has a bitter taste and disagreeable odour rendering the oil non-edible.
The oil is of great value in indigenous medicine as a stimulant and for the treatment of skin diseases; it has antiseptic, antiparasitic and cleansing properties. It is used in medicinal preparations for scabies and leucoderma. The furanoflavones present in karanja oil are helpful in enhancing pigmentation of affected skin. Undistilled oil is used in the manufacture of laundry soap and the distilled oil is used in the manufacture of toilet soap. The sulphonated oil is used in leather industry. Karanja oil is also used in manufacture of phenyles, greases, lubricants, massage oils and/edpoxy compounds. Villagers use this oil for burning lamps. The oil is also reported to have insecticidal properties. The cake is a good fertilizer and has good soil binding property. It also helps to some extent in controlling soil insects and nermatodes.
Physico-chemical constants reported for the oil are : specific gravity 0.9273/30o, refractive index 1.4736/30o, saponification value 181.5, idodine value 89.1, acid value 6.3, actyle value 20.9 and unsaponifiable matter 4.2%. The fatty acid composition of the oil has been reported to be : palmitic (3.7 – 7.9%), stearic (2.4 – 8.8%), arachidic (2.2 – 4.7%), behinic (4.2 – 5.3%), lignoceric (1.1 – 3.5%), oleic (44.5 – 71.3%), linoleic (10.8 – 18.3%) and Eicosenoic (9.5 – 12.4%) acids. Colouring and odouriferous constituents cannot be removed by conventional refining methods. Mixed solvent refining procedure has been developed to produce an oil with fatty acid composition similar to that of groundnut oil.
Leaves are lopped for fodder and also used as green manure. The juice of leaves, stem and roots is considered a remedy for gonorrhoea. Externally the leaves, like the root and seeds, are much used for the treatment of maggot infested ulcers. The leaves contain 17.6% of crude protein, 2.2% of calcium and 0.2% of phosphorus.
Its flowers are useful in diabetes.
The wood is yellowish grey in colour, heavy, moderately strong, moderately tough, hard, medium course textured and interlocked grained. It is not durable, liable to split and warp but seasons well with care and fairly easy to work, turn and finish. The wood is used for construction, tool handles, turnery articles and agricultural implements.
The wood of this tree is a good fuel. It is also commonly used as fuel (calorific value 4839 Kcals per kg) throughout India.
Pongamia starts flowering from the 4th or 5th year of planting. The flowers appear in April to July. There is a positive correlation between the mean display rank and percent flowers turning into galls. Further, there is a positive correlation between attractiveness of flowers with the fruit set percent. Thus, the floral display features enhance the pollination efficiency and also attract the detrimental insects that affect the plants.
Out of the two ovules in the ovary, invariably only one will develop into seed. After fertilization, the early fertilized ovule suppresses the subordinate one by the strong sink activity. The abortion of embryo is due to manifestation of sibling rivalry.
a). SEED COLLECTION AND STORAGE
The pods are collected from April to June. Pods 4-5cm long and 1.5 – 2.5cm wide , broad, pointed at both ends, yellowish grey when ripe, 1 or 2 seeded. Seeds elliptical, reniform, compressed, reddish-brown, fairly hard, 2 to 3cm long.
The pods are dried in sun and seeds are extracted by thrashing the fruits. Seeds do not store well. The natural longevity of seeds is 6 months. They remain viable for a year when they are stored at 5oC. The seeds are stored with the fruit shell unopened in sealed polythene bags.
Seeds are sown in sand trays with the micropyle facing downwards. Seeds start germinating from 10th day of sowing. The initial moisture content of seeds is 6%. Generally seeds do not require any pretreatment before sowing. But soaking the seeds in hot water (50oC+ ) for 15 minutes improves germination percent and also vigour. Some of the pretreatments including growth regulators tried to enhance speed of germination and vigour is given below.
Effect of seed treatment of Pongamia pinnata with hot water and growth regulators on speed of germination and viability.
The occurrence of twin seedlings in Pongamia pinnata while carrying out germination tests has been reported. However the occurrence of twin seedlings (2%) is uncommon.
The germination in this species is hypogeal, i.e., in normal seedlings the cotyledons remain beneath the germination medium while the plumule pushes upwards and emerges above. The plumule is usually unbranched and bear primary leaves at each node. The arrangement of leaves is usually alternate. The primary leaves are simple, more or less cordate in shape with smooth margin. Occurrence of 8 different types of abnormal seedlings has been reported.
Time taken for initial germination 9 days
Germination capacity 50%
Time taken for germinative capacity 25 days
Germinative energy 30%
Purity % 100%
Moisture % 10%
Plant percentage 30%
No. of seeds per kg. 500
No. of seedlings per kg. 150
Viability 6 months.
Pretreatment Remove the fruit sheel be fore sowing.
The seedlings are raised in seed beds or polypots. Seed is sown in previously prepared patches or lines at the break of rains. The seed is dibbled in the nursery beds in the beginning of hot weather, at a spacing of 7.5cm x 1.5cm. Mulching of beds is helpful. In some places seeds are sown in polypots in July to August or small seedlings from the primary beds can be pricked to the poly bags. The seeds start germinating after about 10 days and germination will be complete in about a month.
V. PLANTING PRACTICES FOR THE SPECIES INCLUDING PROPAGATION
Seedlings attain a height of 25 – 30cm by the end of first growing season. When the seedlings attain a height of 60cm they are planted out entire, with the ball of earth, or in the form of stumps. Pits of 30cm3 are appropriate for planting in a plantation scale at an spacement of 3 x 3m.
Studies were carried out on vegetative propagation of Pongamia pinnata by using branch cuttings of mature tree. The cuttings measuring about 30cm long and 4 to 5cm in diameter were treated with 500ppm. of IAA, IBA & NAA for 5 seconds and 24 hours. The rooting percentage, number of lateral roots, root length as well as growth of vegetative parts was higher and excellent in the cuttings treated with 500ppm. of IBA for 5 seconds. The details of the experimental results are tabulated below.
VI. CULTURAL OPERATIONS AND ITS CALENDAR
Two or three weedings are required per year for the first 2 – 3 years of sowing/planting. When it is planted as an avenue tree, side branches should be pruned to get proper bole. A height of 16.5m and grith of 21.6cm at the age of 25 years was reported in a plantation in Uttar Pradesh.
It produces long, later roots. The maximum length of later roots (9 – 10m) in a 18 year old Pongamia Pinnata plant was reported during evaluation of certain leguminous trees for agroforestry.
VII. PEST AND DISEASES
Insect Pests and their management
There are about 30 species of insect pests recorded to cause damage to Pongamia, it raised usually as avenue planting and strip plantations on marginal lands. They include gall inducers, leaf miners, foliage feeders, shoot borers, sap suckers, flower feeders and fruit and seed borers. Of these gall inducers and leaf miners, rank predominant positions because of their destructive potential and ubiquitous occurrence.
Two species of gall midges viz., Microdiplosis pongamiae Mani and Myricomyia pongamiae Mani (Diptera – Cecidomyidae) are the gall inducers commonly encountered. Larvae of Microdiplosis pongamiae, which live in association with a mite Eriophyes Cheriani Massee cause the development of greenish, hollow, polypoid, pedicelled galls on the upper surfaces of leaflets. This midge is a prolific breeder and several generations are produced during a year. The midge larvae and the mites occur together in the galls, and neither is individually responsible for their formation. Not even a single tree of sapling is found devoid the galls and a considerable percentage of leaves bear them. Myricomyia pongamiae is predominantly confined to South India. Eggs are laid on tender shoots, rachis, or midribs of the leaves of the host and the larvae tunnel in and bore upwards and downwards, sometimes feeding for as long as 2 months. They induce the formation of woody indehiscent galls of about 20mm diameter, usually more or less globose but variable, greenish or brownish yellow, glabrous when young and becoming tubercular and punctuate. It is believed that there are 2 generations during a year.
An effective pest management strategy to this problem is not so far evolved. Constant surveillance and timely removal of affected foliage and their destruction by burning or burying may help in reducing the pest population. Foliar spraying with systemic insecticides like Monocrotophos, dimethoate etc., at a concentration of 0.1% together with acaricide like dicofol at a concentration of 0.1% as a prophylactic treatment prior to the onset of the problem is advisable. The other options are search for effective biocontrol agents and pest resistant strains of Pongamia.
The leaf miners constitute mainly two species viz Acrocercops anthracuris Meyrick and Lithocollectis virgulata Meyrick (Lep. Lithocollectidae
Stem/shoot borers constitute mainly two species, the stem borer, Indarbela tetraonis Moore (Lep. Indarbelidae) and the shoot borers Laspeyresia perfricta meyrick (Lep. Tortricidae)
There are about 16 species of defoliators recorded of which the species Eucosma balanoptycha Meyrick (Lep. Tortricidae) Jamides celeno Cramer (Lep. Lyeaenidae), Neptis jumbah moore (Lep. Nymphalidae) and Theretra nessus Drury (Lep. Sphingidae) may be considered to light to moderate damage. All others are just casual feeders. In view of the low profile of the defoliators, control measures are not warranted. Moreover the treatment suggested for gall midges and leaf miners may stand in good stead against the defoliators also.
Seven species of sapsuckers are recorded, all of them being casual feeders. It is interesting to note that Pongamia supports the commercially important Lac insect Laccifer lacca Kerr (Hemi. Lacciferidae) by offering itself as a host.
DISEASES AND THEIR MANAGEMENT
Fusicladium pongamiae causes leaf spot and blight resulting in severe leaf deformities. Foliar spray of Bavistin at 0.1% is found to be affective in minimizing the disease.
The rusts, Ravenelia hobsoni attacks the leaves and produces numerous chestnut brown teliospore heads on the lower surface. Another rust, R. stictica is also known to attack the leaves. Microstroma pongamiae causes white to cream-coloured spots giving a yellowish appearance to the leaves. Other fungi causing leaf spots are phyllochora pongamiae, Robillarda kamatii and Urohendersonia pongamiae. Cercospora pongamiae and Sphaceloma pongamiae cause anthracnose spots on leaves, tender shoots and pods resulting in severe damage and early defoliation in young seedlings and trees. The only powdery mildew recorded on this host is Oidium sp.
Myxosporium phormii attacks stem and branches and causes canker formation. Cuscuta reflexa and Loranthus sp. are the Phanerogamic parasites recorded on this host.
Root and Butt Rot
Ganoderma lucidum, is known to cause white spongy root rot in avenue trees and fomes merillii attacks the base of living trees.
Daldina concentrica causes white rot, mottled and streaked with black whereas Irpex flavus and Polyporus cinerscens are associated with stump rot.