Rambutan
Rambutan (Nephelium lappaceum) is another important fruit tree of humid tropics mostly confined to south-east Asia especially Indonesia, Malaysia and Thailand. In the recent past, this fruit has spread to other humid tropical regions of the world including India. Rambutan, a medium-sized evergreen tree with an open structure growing 12–15m high, is a native of the Malaysian-Indonesian region. It produces ellipsoidal fruits in clusters of 15–20 fruits. Fruits weigh 40–50g each and resemble litchi but because of long, thick, soft hairs or spines on the surface these are known as rambutan (in Malay ‘rambut’ stands for hair). The hairy outgrowth has eye-catching red and yellow colours and it imparts a distinctive exotic appearance to its fruits.
The thin, leathery fruit skin is easily peeled away, revealing a pearly white, gelatinous, juicy pulp (aril) surrounding a large seed. The pulp tends to be attached to the seed in some varieties. In others, it can be readily separated. The translucent pulp is sweet or sub-acid with a refreshing flavour and is akin in many ways to litchi pulp. The fruits are a good source of sugars and vitamin C and are eaten as a fresh dessert fruit. The pulp can be preserved in syrup or used in several conserves.
Climate and soil
Rambutan is strictly a tropical fruit requiring a moist warm climate with a well-distributed annual rainfall of at least 200cm. The plants can grow at 10–500m above mean sea-level, but areas with dry winds are harmful for the tree growth, which leads to browning of leaf margins. In Indonesia, this fruit is distributed in areas with the altitude 30m above sea-level, with 90–150 rainy days in a year and temperature 20°–30°C and relative humidity 60–82%.
Rambutan trees grow best in deep, well-drained soils, rich in organic matter. They can grow in heavy soils, if well-drained, and in sandy soils, if these have good organic matter. A pH of 4.5–6.5 is suitable. At higher pH, iron and zinc deficiencies are common resulting in chlorosis and leaf-yellowing.
Varieties
Since rambutan is a cross-pollinated crop, large genetic variation has occurred in nature over generations and numerous varieties have been identified but their nomenclature is confused. Most of them can be distinguished by spine length, fruit wall colour, aril thickness, aroma, adherence of aril to the seed, vitamin C content and fruit set. Rongrien and Chompu are most popular varieties in Thailand. Both these have crisp arils and are well-suited for canning and for fresh consumption. Bingjai, Lebak Bulus and Rapiah are important varieties of Indonesia, which have sweet, sub-acid and very sweet pulp respectively. Bingjai has long spines while Rapiah fruits are smaller. Some of the good varieties like Azimal (thick aril, sweet to sub-acid pulp), Kelip (medium thick aril, very sweet) and Singapura (thin aril, very sweet) are grown in Malaysia. Trees with male, female and perfect flowers are known in rambutan, but most of the cultivated varieties are generally monoecicus, bearing male and female flowers on the same tree.
Rambutan (Nephelium lappaceum) is another important fruit tree of humid tropics mostly confined to south-east Asia especially Indonesia, Malaysia and Thailand. In the recent past, this fruit has spread to other humid tropical regions of the world including India. Rambutan, a medium-sized evergreen tree with an open structure growing 12–15m high, is a native of the Malaysian-Indonesian region. It produces ellipsoidal fruits in clusters of 15–20 fruits. Fruits weigh 40–50g each and resemble litchi but because of long, thick, soft hairs or spines on the surface these are known as rambutan (in Malay ‘rambut’ stands for hair). The hairy outgrowth has eye-catching red and yellow colours and it imparts a distinctive exotic appearance to its fruits.
The thin, leathery fruit skin is easily peeled away, revealing a pearly white, gelatinous, juicy pulp (aril) surrounding a large seed. The pulp tends to be attached to the seed in some varieties. In others, it can be readily separated. The translucent pulp is sweet or sub-acid with a refreshing flavour and is akin in many ways to litchi pulp. The fruits are a good source of sugars and vitamin C and are eaten as a fresh dessert fruit. The pulp can be preserved in syrup or used in several conserves.
Climate and soil
Rambutan is strictly a tropical fruit requiring a moist warm climate with a well-distributed annual rainfall of at least 200cm. The plants can grow at 10–500m above mean sea-level, but areas with dry winds are harmful for the tree growth, which leads to browning of leaf margins. In Indonesia, this fruit is distributed in areas with the altitude 30m above sea-level, with 90–150 rainy days in a year and temperature 20°–30°C and relative humidity 60–82%.
Rambutan trees grow best in deep, well-drained soils, rich in organic matter. They can grow in heavy soils, if well-drained, and in sandy soils, if these have good organic matter. A pH of 4.5–6.5 is suitable. At higher pH, iron and zinc deficiencies are common resulting in chlorosis and leaf-yellowing.
Varieties
Since rambutan is a cross-pollinated crop, large genetic variation has occurred in nature over generations and numerous varieties have been identified but their nomenclature is confused. Most of them can be distinguished by spine length, fruit wall colour, aril thickness, aroma, adherence of aril to the seed, vitamin C content and fruit set. Rongrien and Chompu are most popular varieties in Thailand. Both these have crisp arils and are well-suited for canning and for fresh consumption. Bingjai, Lebak Bulus and Rapiah are important varieties of Indonesia, which have sweet, sub-acid and very sweet pulp respectively. Bingjai has long spines while Rapiah fruits are smaller. Some of the good varieties like Azimal (thick aril, sweet to sub-acid pulp), Kelip (medium thick aril, very sweet) and Singapura (thin aril, very sweet) are grown in Malaysia. Trees with male, female and perfect flowers are known in rambutan, but most of the cultivated varieties are generally monoecicus, bearing male and female flowers on the same tree.
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