Olive (Olea europea L) is one of the oldest plant cultivated by man in the world. The native home of the olive is considered to be Asia minor, where from it spread to Europe and North African countries. The world area under this crop is 10 million hectares from which 853.1 thousand tones oil is produced annually. According to the latest statistically survey, about 98% of olive trees are grown in the Mediterranean countries
Introduction and Importance:
Olive (Olea europea L) is one of the oldest plant cultivated by man in the world. The native home of the olive is considered to be Asia minor, where from it spread to Europe and North African countries. The world area under this crop is 10 million hectares from which 853.1 thousand tones oil is produced annually. According to the latest statistically survey, about 98% of olive trees are grown in the Mediterranean countries, Italy and Spain alone accounting for 385 million trees. The commercial and wild olive plantation is found into belts around the world between 30-45 o North and South of equator. Since Pakistan is located in this region. Therefore, olive cultivation can be successfully undertaken in the country, provided relevant inputs, incentives and technologies are made available to the forming community.
Nutritive value and composition:
Olive is good source of edible oil and is also used for table purpose particularly for pickles. The olive has not only nutritional and medicinal value but its fat content is also free from cholesterol. It is also used in food preservation, textile industry and cosmetic preparation along with variety of other purposes. It contents six type of acids with a dominating oleic acid content upto 74.5%. Chemical composition of olive fruit, oil and fruit constituents are given in table 1,2 and 3 respectively.
Table-1. Chemical composition of different parts of fruit (%)
Table-2. Composition of olive oil (Medium ripe olives)
500 mg %
Table-3. Description of fruit constituent
The commercial and wild plantation are found in two belts around the world between 30-45 o North and South of the equator. Since Pakistan lies in between these belt, hence it is possible to grow olive in the country . The wild species of olive are found abundantly in different parts of the country particularly in the provinces of NWFP and Balochinstan which indicate that improved varieties can also be grown successfully. Keeping in view the importance of this crop, olive cultivation and improvement work has been initiated at NARC. The survey of potential areas of Pakistan with suitable ecology for olive cultivation indicates that olive can successfully be gown in tribal area in NWFP, Swat, Dir, Malakand, Loralai, Khuzar and Quetta with suitable management practices. Oil Extraction Plant was installed in Tarnab (Peshawar). in order to push the crop on commercial lines. Improved varieties of olive imported from Italy have been planted in Swat, Dir, Malakand, Loralai and at NARC Islamabad. In addition to Italian cultivars, four Turkish olive cultivars were also introduced and planted at NARC for evaluation studies during 1986. Some of these cultivar have shown good performance and giving good yield in Baluchistan and at NARC Islamabad for last 4-5 years.
Climate: The plant is generally grown in Mediterranean region where summers are warm and dry with mild rainy winter. The spring and autumn seasons are short. It also requires some chilling period during winter for successful flowering and fruiting but the winter temperature should not go below 0oC for long time. It can also be grown commercially in sub-tropical zones at the altitude of 2000-3000 ft from sea level but maximum temperature during flowering and fruit setting should not more than 28oC for getting good crop.
Soil: It can be grown in all type of soils provided irrigation water is available but deep well drained sandy loam soil with 5% clay and soil PH from 5.6 to 8.5 is preferred for olive growing.
Propagation: There are two methods of propagation i) Sexual ii) Asexual
Sexual: Olive propagated by seed gives the great deformity of progeny from parent tree. This technique is used only for genetic improvement of the species and for the production of seedling to be used as rootstock.
Asexual: This method include grafting, cutting and root suckers and ovules for propagation.
Grafting: This method is successfully and economically applied for olive propagation particularly for those cultivars with self rooting problem. One year old seedling with stem diameter of 6-8 cm are suitable for grafting. Investigations have shown that high percentage of grafting success can be obtained when plants are grafted during February through pen grafting technique.
Cutting: Olive can be successfully propagated from cuttings under mist. The results of the experiments conducted at NARC reveal that cuttings of 10-15 cm length of last year growth treated with 3000 ppm IBA and plant in sand culture under mist in greenhouse (temperature ranging from 20-28oC with relative humidity 90%) give more than 70% rooting success.
Planting: There are two seasons of olive plantation during the year i.e. autumn and spring. The best period of the year is autumn (September -October) if the area is free from frost. It is because the development of the root system is easier and plants are in more favourable conditions for vegetative growth during next spring. On the other hand, if winter is severely cold, plantation should be done in early spring before the beginning of new vegetative growth. Field should be ploughed well and leveled properly and pits measuring 2 x 2′ should be dug before plantation. Pit should be filled with well rotten F.Y.M mixed with surface soil and silt in the ratio of 1:1:1. Generally olive is planted at 5 x 6 or 6 x 6 m from plant to plant and row to row distance according to the variety and fertility of soil. After planting the tree, irrigate them immediately.
Irrigation: Although olive is drought resistant but cultivated varieties need to be irrigated frequently depending upon the climatic conditions at least for two years untill the trees become established. The incidence of prolonged dry spell leads to the shriveling and drops of fruit after fruit setting.
Under barani condition 400-500 mm average annual rainfall well distributed, particularly during the critical period is considered sufficient for cropping. Where rainfall is not secure, 2-3 irrigation’s at critical stage are very important for getting economical crop. The first critical period starts during the first bud differentiation and blooming , 2nd after fruit setting and during the development of fruit growth.
Pollination: Although olive flowers are hermaphrodite in nature but most of the cultivars are self in compatible, only a few cultivars are self pollinating i.e. Frantoio, Ascolana, Tenera but the production is improved by cross pollination. When cultivars are selected suitable pollinizer varieties should be planted at least 8-10% trees in the grove. Some of the scultivars alongwith their suitable pollinizers are given below:
Fertilizer: Manuring and fertilization encourage the vegetative growth and fruiting of the tree. Application of NPK depends upon the soil condition, fertility of soil and age of the tree. The olive tree needs more nitrogenous fertilizer than phosphorous and potash. Potash and phosphoric fertilizer should be incorporated in the soil before planting of trees at the rate of 200 kg and 300 kg per hectare respectively. It should be mixed thoroughly with soil with deep ploughing. Application of these fertilizers should be repeated after every 3-4 years. The best time of nitrogen fertilizer is before the flowering after fruit setting and at the stone hardening. The schedule of nitrogen fertilizer is given below:
Age of tree N dose/tree Time of application
1 year 60-80 gm urea in 3 doses During the growing season from April to July
2 year 200-250gm urea in two equal doses Before growth start and in June
3 year 300gm (200+100) In the beginning of growth and in June
4 year 400mg urea (200+150) Before the blooming and after fruit setting
5 year 500gm urea (300+200) Before the blooming and after setting
With the age and increasing the production of tree nitrogenous fertilizer should be increased accordingly.
Pruning and training: The main task of pruning is to modify the vegetative growth and regulate its production efficiency. It should also aim at lowering the bearing head, removal of non-bearing wood and proper spacing of shoots. This is attained by thinning out and light heading back of shoot. Olive bears fruit on one year old branch and pruning is generally practiced after every two years.
Picking and harvesting: Olive are picked when the fruit has changed colour from deep green to a straw or cherry red colour but before it turn . Generally olives, are picked on the tree, off the ground and with mechanical device.
Diseases and pests: The common diseases in olive plant are trunk decay, sooty mould and peacock spot. The peacock spot is characterized by zoned ring spots on the leaves which start in January in the lower part of the tree and may result in complete defoliation. Spraying the tree with 2% Bordeaux mixture can control the disease. The bacterial knot appears in the form of numerous irregular tumors and galls resembling canker. It is very contagious and can also be controlled with Bordeaux mixture. The common olives pests are olive fly, olive moth, twig cutters, Bark beetle, Woolly aphid and scale etc. olive moth, twig, cutter, thrips and scales can be controlled with malathion at 2 ml/l. Activities of olive fly starts during August and cause severe damage to the fruit. Rogor at the rate of 1-2 ml/l is considered effective to save the fruit from damage of olive fly. Wooly aphid suck the sap of tree and excrete the white sticky secretion which results in stop of the plant growth. Dimecron/Karate at 1-2 ml/1 lit of water can be used effectively against this insect.
Pickling of a green olive:
The fruits are picked when light green or of straw colour and dipped in 1-2% solution of NaoH. This treatment is continued for 24-48 hours, until the lye penetrate about 3/4 pit of fruit. The lye solution is then removed and fruit, are washed thoroughly with water. During the treatment light is avoided as it results in undesirable darkening of the fruit. After washing, fruit is placed in 6-8% Nacl solution for 2-3 weeks. After that olive are placed in a container having acetic acid.
Key Reference : parv.org.pk