FRUIT DIVERSITY—EXPLORATION AND DISTRIBUTION

The concept of center of origin was conceived by N. I. Vavilov based on his studies of a vast collection of plants at the Institute of Plant Industry, Leningrad during his tenure as Director from 1916 to 1936. According to Vavilov, crop plants evolved from wild species in the areas showing great diversity and termed them as primary centers of origin. But in some areas, certain crop species show considerable diversity of forms although, they have not originated from such areas which are known as secondary centers.

MEDITERRANEAN FRUITS

1.3.1.1 DATE PALM

Date palm (Phoenix dactilifera, Arecaceoe)—a dioecious palm—is thought to be indigenous from Northern Africa through the Arabian peninsula to northern India (Smartt and Simmonds 1995). The precise origin of the cultivated date is considered to be lost in Antiquity. Date palm is probably the most ancient cultivated tree in the world and Vavilov considered the origin of the date to be the mountains of northeastern Africa in Ethiopia and Eritrea but there is evidence that the first cultivation occurred in the Lower Mesopotamian Basin. The old world of date palm stretches horn east to west (±8000 km) and from north to south (±2000 km). According to Dowson (1982), date palm covers 3% of the world's cultivated surface. In the early years of the Nineteenth Century (1912), the date palm was introduced into the western part of North America (Colorado Desert, Atacama Desert and other regions). The world total number of date palms is about 100 million, distributed in 30 countries. At the present time, there are over 3000 cultivars, of which 60 are widely grown. Some cultivars have been known for a thousand years. Cultivars have been divided into soft and semidry, based on moisture content and an increasing proportion of sucrose, rather than glucose and fructose.

1.3.1.2 OLIVE

Olive (Olea europea, Oleaceae) is a slow-growing, long-lived, evergreen tree uniquely adapted to the climate of the Mediterranean basin and considered a defining feature of this climate (Smartt and Simmonds, 1995). Indigenous types are still widely found with archeological evidence as far back as 12,000 years ago (Blazquez, 1996). The cultivated olive originated about 6000 years ago in Asia Minor, but was generally unknown to the Babylonians and Assyrians whose source of oil was sesame and walnut. The olive moved from Egypt to Carthage in North Africa, reaching Italy in the 7th to 6th century b.c. Olives were introduced to South America in the 16th century and introduced to Mexico, California and Australia in the 20th century. In Pakistan and India, the cultivated olives (Olea europaea L.) were introduced in 1950s as evidenced by the existing plantations in Mingora (SWAT), Rawalpindi, and Pinjore in India, where olive cultivation started 40 years ago. India has extended commercial olive plantation activities and olive oil industries in Himachal, Jammu, and Uttar Pradesh. Warm-temperate climate is considered best for olive and three main geographic areas are suitable for olives in the world; they are: (1) the Mediterranean Region where there is the maximum concentration of olives in the world, (2) between 30° and 45° latitude in both the Hemispheres, and (3) higher altitudes at lower latitudes. There are many countries where olives are commercially grown. Mediterranean countries produce largest amount of olives in the world. Spain, Italy, Tunisia, Greece, and so on have maximum acreage under olive cultivation. Many olive cultivars exist not only in the Mediterranean region but also in other countries. In Italy alone there are over 600 cultivars or cultivar groups with 200 million trees (Bartilocci and Bhuddi, 1999). There are other 700 million trees totaling 900 million trees in the World. In each countiy, there are cultivars or cultivar groups suitable for each particular geographic area.

1.3.1.3 GRAPE

Wild grapes of the Old World (Vitis sylvestris, Vitaceae) are indigenous to the south Caspian belt, Turkey, and the Balkans, and are widely distributed in the northern Mediterranean area including the Black and Caspian Seas (Reisch and Pratt, 1996). Grape is grown under a variety of soil and climatic conditions in three distinct agro-climatic zones, namely, sub-tropical, hot tropical, and mild tropical climatic regions. The number of grape cultivars thr oughout the world is very large but in many countries in the tropical zone only a relatively small number of cultivars are present and have been evaluated for suitability to local climatic conditions.

1.3.1.4 POMEGRANATE

Pomegranate (Punica granatum, Pimicaceae), native to the southern Caspian belt (Iran) and northeast Turkey, is a Bronze Age fruit that has been cultivated for 5000 years (Goor and Nurock, 1968; Zohary and Spiegel-Roy, 1975). In addition to Iran which has the highest area under cultivation, highest production and is the number one exporter, other countries including Turkey, Afghanistan, Pakistan, India, Armenia, Georgia, Tajikistan, Jordon, Egypt, Italy, Tunisia, Azerbaijan, Libya, Lebanon, Sudan, Myanmar, Bangladesh, Mauritania, Morocco, Cyprus, Spain, Greece, France, China, Japan, and the U.S.A. are among the countries which have areas under pomegranate cultivation. However, among these countries, India, The Central Asian Republics, Upper caucuses, and Spain have the highest area under cultivation and varietals diversity. There are literally hundreds of varieties of pomegranate across the world. Some varieties are native to one area of the world or another and can only thrive in those areas.

CENTRAL ASIAN FRUITS

l. 3.2.1 POME FRUITS

The pome fruit species include Pyrus pashia, Malm domestica, Cydonia oblonga, Sorbus Janata, S. tianshanica, Crotaegus songarica, C. affinis, C. intergerrima, Cotoneaster lindlegi, and C. nummularia. Cydonia oblonga (quince) is cooked, boiled, and preserved in sugar, and is also used for medicinal putposes. Sorbus (S. Janata) occurs at elevations of 2000-3600

m. The fruit is round, 2-4 cm in diameter, and orange with a heavy red blush flesh. The soft fruit is edible and sweet. The fruit can be kept for one month after harvesting. Carteagus (C. songarica) is common in cultivated areas of Pakistan and so on at altitudes of 925-2800 m. The mature fruit hangs on the tree for several months. As well as being grown for its fruit, C. songarica is also used as root stock for quince and apple. The Cotoneaster genus is represented by C. affinis, C. integerrima, C. JindJeyi, and C. nummularia. Cotoneaster affinis is found associated with Pinus gerardiana, Cedrus deodara, Ulmus, and Pyrus pashia at altitudes of 1100-3000 m, whereas C. integerrima is found at altitudes of 2200-4000 m. All four Cotoneaster species have ornamental value and the fruits are edible.

1.3.2.1.1 Apple

Apple, as one of the most widely cultivated fruit tree crops in the world, unsurprisingly, is a top global commodity. China produces approximately half of the total apple production, followed by the United States, Turkey, and Poland. It is presumed that the center of diversity of apple is located around central Asia. There are 24 primary species of Malus distributed in Europe, Central Asia, and Eastern Asia, and three in North America (Way et al., 1990). Most of the wild apples are small and bitter. However, the large, sweet-smelling domestic apple (Malus domestica) clearly originated in Central Asia, specifically Almaty, Kazakstan (Dzhangaliev, 2003). Today, there are more than 6000 apple cultivars (Hancock et al., 1996), each having been developed for specific human preferences such as taste, size, different uses including eating, cooking and cider production, and for physiological reasons, for example, resistance to crop disease, harvest time, storability, and climate suitability.

1.3.2.1.2 Pear

Belonging to the genus Pyrus, which originated in the Tertiary period, in Central Asia, the pear had its dispersion from northern Italy, Switzerland, former Yugoslavia, Germany, Greece, Moldova, and Ukraine to the East, in countries such as Iran, Uzbekistan, China, Japan, Korea, and Bhutan. Commercially, it is divided into two major groups: European and Asian pears. The European pears are characterized by intense flavors, flesh softening after the climacteric, and a wide range in sizes and shapes. There are 23 wild species cataloged, all native to Europe, temperate Asia, and northern mountainous regions of Africa. Many improved varieties have been derived from this species.

1.3.2.2 STONE FRUITS

Stone fruits are represented by 12 species. The genus Primus, and family Rosoceae, includes almond, apricot, sweet cherry, sour cherry, peach, nectarine, and plum. The almond is cultivated for its seed, while as other temperate stone fruits are soft-fleshed and are known for their delectable flavors. According to Watkins (1995), Primus originated in Central Asia, and their secondary centers of origin is in Eastern Asia, Europe, and North America. The Roman names for the stone fruits suggest their presumed origin peach (persica) from Persia, apricot (arineiiiaca) from Armenia, cherry (cerasus) from Kerasun on the Black Sea, but it is clear that these locations were clearly way stations from Central and East Asia. The peach originated in China. The stone fruits have a large number of ecotypes.

CHINESE AND SOUTH ASIAN FRUITS

1.3.3.1 PEACH

China is the origin of the peach (Primus persica, Rosaceae), domesticated before 3300-2500 b.c. (Faust and Timumon, 1995). Cultivated peaches are divided into clingstones and freestones, depending on whether the flesh sticks to the stone or not; both can have either white or yellow flesh. Peaches grow in a fairly limited range in dry, continental, or temperate climates, since the trees have a chilling requirement that tropical or subtropical areas generally do not satisfy except at high altitudes (e.g., in certain areas of Ecuador, Colombia, Ethiopia, India, and Nepal). Hundreds of peach and nectarine cultivars are known. These are classified into two categories—freestones and clingstones. Freestones are those whose flesh separates readily from the pit.

1.3.3.2 CITRUS

Rutaceae consists of six genera of which three Citrus, Poncirus (trifoliate orange), and Fortunella (kumquat) have commercial value. Genus Citrus can be said to include a diverse group of evergreen Old World fruits originating in southeast Asia (eastern India, Burma, and southern China) even though some researchers believe that its origin is Australia, New Calen- donia, and New Genuine. It is grown throughout the tropics and subtropics worldwide (Soost and Roost 1996). The horticultural group include the main species and their hybrids namely, citron (C. medico), lemon (C. Union), lime (C. aurantifolia), pummelo (C. grandis), sour orange (C. aurontium), sweet orange (C. sinensis), mandarin (C. reticulata), and grapefruit (C. paradisi). Major commercial citrus growing areas include southern China, the Mediterranean Basin (including southern Spain), South Africa, Australia, the southern United States, Mexico, and parts of South America. In the United States, Florida, California, Arizona, and Texas are major producers, while smaller plantings are present in other Sun Belt states and in Hawaii. According to De Candolle, citron is found in the Indian Himalayas and has been reported from Iran in 300 b.c. The sour and sweet orange has been introduced in Europe by Arabs during 11th century. Mandarins have originated in Vietnam and China, from where they spread to Japan in the 12th century and Europe after 1805 (Roost et al., 1995).

1.3.3.3 BANANA AND PLANTAIN

Banana, botanically a beriy, is produced by several kinds of herbaceous flowering plants in the genus Musa. Bananas and plantains (Musa species, Musaceae) are indigenous to southeast Asia and the Pacific (Simmonds,

  • 1995). Bananas refer to fresh fruit types, while plantains are cooking types. Banana is grown in many countries of Asia, Africa, and South America. The genus Musa is divided into Eumusa, Rdhodochalamys, CaJIimusa, Australi- musa, and incertae sedis. The edible bananas belong to Eumusa. There are more than 300 varieties being grown only in India with different names at different places.
  • 1.3.3.4 MANGO

Most important crops of family Anarcardiaceae include mango (Mangifera indica) and pistachio nut (Pistacia vera) which are native to East Asia, and cashew nut (Anacardium accidental) is native to tropical Brazil. The mango, which is most popular fruit of India, is the fourth most important fruit crop of the world. The genus Mangifera has almost 41 species but all edible ones belong to Mangifera indica. The mango has its origin in Indo-Burma region and is allopolyploid between M. indica and M. sylvatica. Mango is grown in several countries of tropical and subtropical world. There are more than thousand varieties of mango grown in India only.

1.3.3.5 JAPANESE PERSIMMON

Persimmon belongs to genus Diospyros and family Ebenaceae (.r = 15) and consists of about 400 species which are widely distributed in the tropics of Africa, Asia, and Americas. The temperate persimmon species is known as D. kaki, (2n = 90). It is also known as kaki or Japanese persimmon and has originated in China. It is also distributed in the United States (California), Israel, Italy, Brazil, Australia, and New Zealand (Yonemori et al., 2000). There are many varieties of persimmon presently being cultivated in the world.

1.3.3.6 KIWI FRUIT

Actinidia deliciosa, in family Actinidiaceae has a chromosome no of 2n = 174. It is a dioecious vine, and is an example of an ancient fruit species domesticated in the 20th century (Ferguson and Bollard, 1990). A. Hayward Wright selected one seedling which was subsequently named as “Hayward,” became the mainstay of the world industry. It is considered as one of the potential crops of temperate regions of India.

AMERICAN FRUITS

1.3.4.1 STRAWBERRY

The cultivated strawberry is the most important and widely grown berry fruit. Fragaria vesca, also known as the wood strawberry, is a diploid species (2n = 16) with small fruit with aroma and has been found in Europe, northern Asia, northern Africa, and North America. Fragaria silvestris and everbearing strawberry is cultivated in Europe as an ornamental as well as a fruit crop. The hexaploid species, F moschata also known as haut- bois, was briefly grown in England. The modern cultivated strawberry is a hybrid of F. Chileonsis and F virginiana. The tetraploid species F. moupiensis is found in eastern Tibet and western China and F. orientalis in western Siberia. Several cultivars have been bred to suit different conditions of moderate, Mediterranean, subtropical, and even high altitudes under tropical climates .

1.3.4.2 BRAMBLES

The genus Rubtis, Rosaceae (x = 7), is veiy diverse with many species in the world. The cultivated Rtibtis species are collectively known as brambles. It includes black raspberry {R. occidentalis), red raspberry (R. idaens), which are diploids with In = 14, and also polyploid blackberries. It also includes the interspecific hybrids between blackberry and raspberry, such as, tayberry and loganberry (2n = 42), and boysenberry (2n = 49) (Jennings, 1995).

1.3.4.3 VACCINIUMS

Species of Vaccinium, Ericaceae (x = 12), include cultivated cranberry and blueberries, both have been domesticated during the 20th century. A number of Vaccinium species such as bilberry (V. myrtillus) and bog bilberry (V uliginosum) are potential domesticates (Galletta and Ball- ington, 1996).

1.3.4.4 PINEAPPLE

Pineapple (Ananas comosus, Bromeliaceae) one of the most wanted tropical fruits was domesticated in tropical South America (Paraguay), probably north of the Amazon River with a possible secondary center in southeast Brazil (Leal, 1995). The pineapple fruit resembles a pine cone and is extremely sweet. The important pineapple growing countries are Hawaiian Islands, Philippines, Malaysia, Thailand, Ghana, Brazil, Mexico, Taiwan, South Africa, Australia, and India. Their crop is divided into about six cultivar groups (Spanish, Cayemie, Pernambuco, Queen, and Maiopure), but only “Cayenne” and “Queen” are commercially important.

1.3.4.5 AVOCADO

Persea americana is one of the 1900 species of family Lcutraceae with about 50 tropical genera. More than 700 varieties of the crop were tried in USA during the first half of the 19th century only. The early history of avocado (P. americana) is unknown but it seems to have originated from southern Mexico to present day Panama (Bergh and Lahav, 1966). The avocado is one of the most nutritive fruits with buttery consistency in pulp.

1.3.4.6 PAPAYA

Carica papaya L. of family Enrphobiacia, is one among the 40 species of the genus and is indigenous to tropical America (Purseglove, 1968). Papaya (Carica papaya), an unusually interesting plant derived from natural hybridization of C. peltata. It is grown all over in tropical and subtropical countries of the world. Many varieties of papaya have been developed throughout its cultivation history. It contains a proteolytic enzyme known as papain, which has been exploited as a meat tenderizer.

 
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