Avocado Production in India - Saurindra P. Ghosh*

* Deputy Director-General (Horticulture),Indian Council of Agricultural Research, New Delhi, India.

Avocado is a native of tropical America. It originated in Mexico and Central America, possibly from more than one wild species. The early Spanish explorers recorded its cultivation from Mexico to Peru but it was not in the West Indies at that time. It was introduced into Jamaica in 1650 and to Southern Spain in 1601. It was reported in Zanzibar in 1892. It was first recorded in Florida in 1833 and in California in 1856.

Avocado is the most nutritive among fruits and is regarded as the most important contribution of the New World to human diet. The fruit is relished by some people, but not by others. The pulp is rich in proteins (up to 4%) and fat (up to 30%), but low in carbohydrates. The fat is similar to olive oil in composition and is widely used in the preparation of cosmetics. Avocados have the highest energy value (245 cal/100 g) of any fruit besides being a reservoir of several vitamins and minerals (Table 1).

Avocado is mainly used fresh, in sandwich filling or in salads. It can also be used in ice creams and milk shakes and the pulp may be preserved by freezing. Three antifungal compounds have been isolated from the peel extracts of immature fruits of the Green cultivar.

Table 1. Chemical Composition of Avocado Fruit (per 100g of edible portion)

I. General Composition		III. Minerals (mg)
Energy value (cal.)	245.0	Calcium	10.00
Protein (g)	1.7	Chlorine	11.00
Fat (g)	26.4	Copper	0.45
Total carbohydrates (g)	5.1	Iron	0.60
Crude fibre (g)	1.8	Magnesium	35.00
		Manganese	4.21
II. Vitamins (mg)		Phosphorus	38.00
Vitamin A as carotene	0.17	Sodium	368.00
Ascorbic acid	16.00	Sulphur	28.50
Niacin	1.10
Riboflavin	0.13
Thiamine	0.06

Source: Madhav Rao and Abdul Khader, 1977

2.1 Major areas where avocados are grown

Avocados can be grown on a wide range of soils, but they are extremely sensitive to poor drainage and cannot withstand water-logging. They are intolerant to saline conditions. Optimum range of pH is from 5 to 7. Depending on the race and varieties, avocados can thrive and perform well in climatic conditions ranging from true tropical to warmer parts of the temperate zone.

In India, avocado is not a commercial fruit crop. It was introduced from Sri Lanka in the early part of the twentieth century. In a very limited scale and in a scattered way it is grown in Tamil Nadu, Kerala, Maharashtra, Karnataka in the south-central India and in the eastern Himalayan state of Sikkim. It can not tolerate the hot dry winds and frosts of northern India. Climatically, it is grown in tropical or semitropical areas experiencing some rainfall in summer, and in humid, subtropical summer rainfall areas.

2.2 Varieties

All three horticultural races adapted to tropical and sub-tropical conditions i.e. West Indian, Guatemalan and Mexican have been tried in India. The cultivars of West Indian race are grown in localized pockets in Maharashtra, Tamil Nadu and Karnataka. In tropical and near-tropical areas, only West Indian race is well-adapted but its hybrids with Guatemalan (e.g. Booth selection) perform well and are considered valuable for extending the harvest season. In less tropical regions, hybrids of Guatemalan with Mexican race predominate since they combine the cold hardiness of the latter with the superior horticultural traits of both and also bridge the two seasons of maturity. In the eastern Himalayan state of Sikkim, avocado has been introduced successfully in hill ranges with an altitude of 800 to 1,600 metres. Both the Mexican and Gautemalan races are grown successfully in Sikkim. In avocado-growing areas of Sikkim, temperatures range from 12 to 30°C with an average annual rainfall of 2,000 millimetres. The Mexican race is cultivated on mid-altitude hills (pH 5-6).

The characteristics of the major avocado races are:

a) Mexican race: Small (250 g) fruit type, ripening 6 to 8 months after flowering. Fruits have thin smooth skin with a large seed fitting loosely in the central cavity. Oil content is up to 30 per cent in the fruits. Trees of this race are cold hardy.

b) Guatemalan race: Fruits fairly large, weighing up to 600 g and borne on long stalks. The fruits ripen 9-12 months after flowering. Fruit skin is thick and often warty. Seeds, held tightly in the hollow of the fruit, are small. The oil content in fruits ranges between 8 and 15 per cent.

c) West Indian race: Fruit medium in size and the fruit skin smooth, leathery and glossy. Fruits are borne on long stalks and require up to 9 months for ripening from the date of flowering. Its seeds are large, fitting loosely in the cavity. The oil content of the fruit is low (3-10 per cent). This race is suitable for warm tropical climates.

The varieties that are cultivated in India go by several names, such as Purple, Green, Fuerte, Pollock, Peradeniya Purple Hybrid, Trapp, Round and Long. Among the several existing varieties, perhaps Fuerte is the most widely grown, but it is regarded as unsuitable for the tropics. The Purple and Green varieties were introduced into India from Ceylon in 1941.

The following varieties have been introduced at the Fruit Research Station, Kallar, Tamil Nadu: Long, Round, Fuerte, Pollock, Peradeniya Purple Hybrid, Shambaganur and Trapp.

The performances of avocado varieties in the Sikkim state are as follows:

Fuerte: Grown successfully in the mid-altitude hills of Sikkim. Fruits, pyriform, weight between 200 and 400 grams each.

Pinkerton: An established variety from California, USA, having pyriform green fruits. The fruit weight varies from 200 to 400 grams.

Green: A successfully grown variety of Guatemalan race with oval-shaped, greenish or light green fruits. Fruit size is similar to Fuerte or Pinkerton.

Hass: Also suitable for Sikkim, with fruit at maturity being purple in colour and medium in size.

In India, avocado is commonly propagated through seeds. The viability of seeds of avocado is quite short (2 to 3 weeks) but this can be improved by storing the seed in dry peat or sand at 5(C. Removal of seed coat before sowing hastens germination. In Sikkim, all the trees grown are seedlings in origin. The seeds taken from mature fruits are sown directly in the nursery or in polyethylene bags. When 6-8 months old, the seedlings are ready for transplanting. Such seedling trees at 10-15 years produce 300 to 400 fruits. Vegetative propagation by means of budding or grafting has resulted in establishment of selected varietal clones. Mexican race is reported to provide almost all of the rootstock requirements in California. Generally, it is used also in Israel and South Africa. The Gautemalan race is more sensitive to cold and has also proved more susceptible to high pH chlorosis and to Verticillium wilt. West Indian stocks are preferred in warmer regions or where salinity is a problem. Need of Phytophthora-resistant rootstocks is recognized as the most important factor for the success of its cultivation. At the Fruit Research Station, kallar, in the Nilgiri Hills of Tamil Nadu, layering as well as inarching gave up to 75 per cent success, while in West Bengal chip-budding is reported to be successful. In India, presently, there is no commercial nursery engaged in vegetative propagation of avocado, nor is there any initiative either at governmental or private level to undertake nursery production of avocado planting material.

4. ESTABLISHMENT OF ORCHARDS

If an avocado plantation is to be established in a relatively new area, the varieties to be selected for planting should belong to both A and B groups and their flowering must overlap. The proportion of A and B group varieties can be 1:1 or 2:1.

Avocado is planted out to a distance of 6 to 12 metres depending on the vigour of variety and its growth habit. For varieties having a spreading type of growth, like Fuerte, a wider spacing should be given. In areas prone to excess water, they should be planted on mounds as avocados cannot withstand waterlogging. In Sikkim, a planting distance of 10 x 10 metres on hills slopes (on half-moon terraces) is preferred and planting is done in June-July. Pits of 90 x 90 centimetres are dug during February-March, and filled with farmyard manure and top soil (1:1 ratio) before planting. In Coorg, a region of Karnataka state, they have been planted also as one of the mixed crops in a primarily coffee-based cropping system.

5. CARE AND MANAGEMENT OF ORCHARDS

Pruning is rarely practised except with upright varieties such as Pollock. In spreading varieties like Fuerte, branches are thinned and shortened. Heavy pruning has been found to promote excessive vegetative growth, consequently reducing the yield.

Sprinkler irrigation has been reported to improve the fruit size and oil percentage; also, it advances harvesting time. Irrigation at intervals of three to four weeks during the dry months is beneficial to avocado. To avoid moisture stress during winter season, mulching with dry grass/dry leaves is desirable. Flooding is undesirable as it promotes root rot incidence.

Avocados need heavy manuring, and application of nitrogen has been found to be most essential. In general, young avocado trees should receive N, P₂O₅ and K₂O in a proportion of 1:1:1 and older trees in the proportion of 2:1:2. At a pH of above 7, iron deficiency symptoms may appear, which may be corrected by applying iron chelate at the rate of 35 g/tree.

Various micronutrients (Fe, Zn, B) have profound influences on tree growth, nutrient uptake and yield of avocado. Integrated nutrient management with inorganic fertilizer, supplemented by organic manuring, is advocated for avocado.

In Sikkim, the soil is deficient in nitrogen, zinc and boron. Application of urea in two split doses, in March/April and September/October (just before and after the onset of the monsoon) is recommended. Foliar application of zinc sulphate (0.5 per cent) may be undertaken in April-May, and other fertilizers applied in soil during March-April. A tentative fertilizer schedule recommended for Sikkim (Upadhyay and Srivastava, 1996) is shown in Table 2.

Table 2. Fertilizer Schedule for Avocado in Sikkim

Manure/ Fertilizer (kg/tree)	Time of Application	Age of Plants (year)
		1st	2nd	3rd	4th	5th	6th	7th & above
Farmyard manure	February/March	-	10	20	30	40	50	60
Urea	March/April	0.10	0.15	0.20	0.25	0.30	0.35	0.40-0.60
	September/October	0.10	0.15	0.20	0.25	0.30	0.35	0.40-0.60
Muriate of potash	March/April	0.10	0.20	0.30	0.40	0.50	0.60	0.70-0.80
Bone-meal	March/April	0.30	0.40	0.50	0.60	0.70	0.80	1.00-1.50

Among insect pests, scales, mealy bugs and mites are the important ones, and may be controlled by suitable insecticides. Fruit spot disease caused by Colletotrichum gleosporioides results in shedding of young fruits. Fruits often become deformed. The infection may remain latent in some fruits. Another strain of the same fungus causes leaf spot. Accelerated softening of fruits caused by Fusarium solani and F. sambucinum has been reported. The Fuerte cultivar is reported to be more susceptible to anthracnose (Glomerella cingulata var. minor) and stem-end rot (Dothiorella aromatica) from fruit set till harvest. The time of infection has been found to vary with the seasons and is related to rainfall. In addition, Cercospora sport (Cercospora purpurea) and scab (Sphaceloma perseae) have been found to attack both leaves and fruits also.

The most serious disease of avocado is the root rot caused by Phytophthora cinnamoni, leading to death of plant. The disease situation is aggravated by ill drained and waterlogged conditions. Metalaxyl (Ridomil) mixed with soil before planting or applied as a soil drench controls root rot at least for four months after treatment.

6. FRUIT HARVESTING AND YIELDS

Avocado plants raised from seeds start bearing five to six years after planting. Mature fruits of purple varieties change their colour from purple to maroon, whereas fruits of green varieties become greenish-yellow. Fruits are ready for harvest when the colour of seed coat within the fruit changes from yellowish white to dark brown. Mature fruits ripen six to ten days after harvesting. The fruits remain hard as long as they stay on the trees, softening only after harvest.

The yield ranges from about 100 to 500 fruits per tree. In Sikkim, specifically, on average 300-400 fruits can be harvested from 10-15 years old trees.

In Sikkim, fruits of Purple variety are harvested during July, and for Green variety September-October is the usual harvesting time. In Tamil Nadu, July-August is the peak harvest time. The yield performance of avocado, both in tropical southern India and humid sub-tropical northeastern India is highly satisfactory.

7. POST-HARVEST HANDLING, STORAGE AND MARKETING

Avocados do not ripen on the tree, and fruits soften only after they are picked. Fruits need to be picked carefully. They should be harvested at the correct stage of maturity, when they are still hard and have a minimum oil content of 12 per cent.

In India, fruits of 250 to 300 grams in size are preferred. Most popular varieties are Hass, Fuerte and Green. Hard, mature fruits are harvested and allowed to ripen during transport and distribution. Up to 14 days transport time is considered satisfactory, though unripe avocados can be stored for up to four weeks if the temperature is kept between 5.5 and 8°C. Presently, there is no organized marketing system for avocado as the production is small and production areas are scattered.

8. POTENTIAL FOR AVOCADO PRODUCTION DEVELOPMENT

The agro-climatic conditions prevailing in various parts of the country appear to be favourable for bringing more areas under avocado. Presently, plantations are not well organized and they are scattered. Also, quite a good number of improved varieties are now available with higher yield potential. Vegetative propagation techniques have also been standardized. Multiplication of a large number of high-quality nursery plants of selected varieties and their systematic planting, both in tropical southern India and humid semi-tropical areas of the northeastern region of India, could help to place avocado properly on the fruit map of India. The research support for the crop is still very poor, but the available research information from Tamil Nadu and Sikkim amply demonstrate that size, colour and quality of fruits attained in India are comparable with those of avocado fruits grown elsewhere. Avocado is grown successfully in neighbouring Sri Lanka, where good-quality fruits are harvested during May to August and December to January at different regions. Similar agro-climatic conditions to Sri Lanka are available in the Andamans and Nicobar Islands and in the tropical southern India. With proper varietal selection it should be possible to exploit also the possibility of out-of-season production, thus enhancing the availability of fruits for a longer period during the year. Avocado fruits produced in the country can be marketed without much difficulty, particularly to meet the requirement of the growing tourist industry. The mainland India and the Andaman and Nicobar Islands are attracting foreign tourists in a large number of places, where avocado could find a good market access. Avocado has also a good export potential.

9. CONSTRAINTS IN AVOCADO PRODUCTION DEVELOPMENT

One of the important constraints appears to be due to the consumer preference. In the domestic market the avocado may not be liked by the common people due to the nature of its taste and also due to availability of many other tropical fruits throughout the year which are more palatable than avocado. Nevertheless, due to increasing health consciousness among the educated population and the high nutritive value of avocado, it is expected to find its rightful place in the Indian market in due course. The successful introduction of avocado and its wide acceptance among the tribal population of the hilly state of Sikkim indicate that for household nutrition security avocado should be a potential fruit crop in India.

10. GOVERNMENT POLICIES AND PLANS FOR RESEARCH AND DEVELOPMENT OF AVOCADO

Presently, there is no definite governmental plan to strengthen research and development of avocado in India. Research centres in Tamil Nadu and in Karnataka are maintaining some germplasm of avocado in their collections.

11. CONCLUSIONS

Due to the availability of a large number of fruit crops in India and consumer preference for more palatable fruits of sweet taste, avocado has not caught the imagination of the average Indians. With some governmental support it can be popularized in the country and it can provide much needed household nutrition security to the Indian population.