**1.4 Nutritional facts**

198 Agricultural Science

*Vigna radiata* (L.) Wilczek [Synonyms: *Phaseolus radiatus* L. (1753), *Phaseolus aureus* Roxb. (1832)], often known as green gram/mung bean, is native to India and Central Asia. It has been grown in these regions since prehistoric times (Vavilov, 1926) and as an important legume crop in India throughout the year. The Sanskrit name for green gram is *mudgaparni* or *mashaparni* as per ancient Indian literature the *Yajurveda* (c. 7000 BC). While green gram cultivation spread over to many countries, especially in tropical and subtropical Asia, black gram (*Vigna mungo*) cultivation has remained more or less confined to South Asia. The progenitor of these pulses is believed to be *Vigna trilobata*, which grows wild in India (Nene, 2006). The more common vernacular names include: mung bean, green gram, golden gram (En). Haricot mungo, mungo, ambérique, haricot doré (Fr). Feijão mungo verde (Po).

The genus *Vigna* comprises about 80 species and occurs throughout the tropics. *Vigna radiata* belongs to the subgenus *Ceratotropis*, a relatively homogenous and morphologically and taxonomically distinct group, primarily of Asian distribution. Other cultivated Asiatic *Vigna* species in this subgenus include *Vigna aconitifolia* (Jacq.) Maréchal (moth bean), *Vigna angularis* (Willd.) Ohwi & Ohashi (adzuki bean), *Vigna mungo* (L.) Hepper (black gram or urd bean), *Vigna trilobata* (L.) Verdc. (pillipesara) and *Vigna umbellata* (Thunb.) Ohwi & Ohashi (rice bean). Hybrids have been obtained between many of these species. The species have often been confounded, especially *Vigna radiata* and *Vigna mungo*. The wild types of mung bean, which are usually smaller in all parts than cultivated types, are usually classified into 2 botanical varieties: – var. *sublobata* (Roxb.) Verdc., occurring in India, Sri Lanka, South-East Asia, northern Australia (Queensland), in tropical Africa from Ghana to East Africa, southern Africa and Madagascar; – var. *setulosa* (Dalzell) Ohwi & Ohashi, with large, almost orbicular stipules and dense long hairs on the stem, and occurring in India, China, Japan and Indonesia. The cultivated types of mung bean are grouped as *Vigna radiata* var. *radiata*, although a classification into cultivar groups would be more appropriate. Two types of mung bean cultivars are usually distinguished, based mainly on seed colour: – golden gram, with yellow seeds, low seed yield and pods shattering at maturity; often grown for forage or green manure; – green gram, with bright green seeds, more prolific, ripening more uniformly, less tendency for pods to shatter. Two additional types are

recognized in India, one with black seeds and one with brown seeds (Mogotsi, 2006).

Mature mung bean seeds or flour enter a variety of dishes such as soups, porridge, snacks, bread, noodles and even ice-cream. In Kenya mung bean is most commonly consumed as whole seeds boiled with cereals such as maize or sorghum. Boiled whole seeds are also fried with meat or vegetables and eaten as a relish with thick maize porridge ('ugali') and pancakes ('chapatti'), whereas consumption of split seeds (dhal) is common among people of Asian descent. In Ethiopia the seeds are used in sauces. In Malawi the seeds are cooked as a side dish, mostly after removing the seed coat by grinding. In India and Pakistan the dried seeds are consumed whole or after splitting into dhal. Split seeds are eaten fried and salted as a snack. The seeds may also be parched and ground into flour after removing the seed coat; the flour is used in various Indian and Chinese dishes. The flour may be further processed into highly valued starch noodles, bread, biscuits, vegetable cheese and extract for

**1.2 The plant** 

**1.3 Uses** 

Mchooko, mchoroko (Sw) (Mogotsi, 2006).

Green gram is an important source of easily digestible high quality protein for vegetarians and sick persons. It contains 24 per cent protein, 0.326 per cent phosphorus, 0.0073 per cent iron, 0.00039 per cent carotene, 0.0021 per cent of niacin and energy 334 cal/100g of green gram. The gap between realizable and actual yields needs to be bridged up with appropriate technologies. The latter basically revolves around two aspects: production and protection. Although the former has been a subject of greater emphasis at all levels of strategy, yet the latter continues to suffer from neglect and a sort of apathy under the cover of ignorance, economic status of the farmers and many more factors. In India, Acharya (1985) has pointed out that plant protection remains a most neglected aspect in pulse cultivation; further stating that only 5 to 6 per cent of the growers use plant protection measures in only 1.5 per cent of the total area under this crop. In view of the above facts, for the control of various pests in green gram, only certain insecticides have been recommended by several workers.

The composition of mature mung bean seeds per 100 g edible portion is: water 9.1 g, energy 1453 kJ (347 kcal), protein 23.9 g, fat 1.2 g, carbohydrate 62.6 g, dietary fibre 16.3 g, Ca 132 mg, Mg 189 mg, P 367 mg, Fe 6.7 mg, Zn 2.7 mg, vitamin A 114 IU, thiamin 0.62 mg, riboflavin 0.23 mg, niacin 2.3 mg, vitamin B6 0.38 mg, folate 625 μg and ascorbic acid 4.8 mg. The essential amino-acid composition per 100 g edible portion is: tryptophan 260 mg, lysine 1664 mg, methionine 286 mg, phenylalanine 1443 mg, threonine 782 mg, valine 1237 mg, leucine 1847 mg and isoleucine 1008 mg. The starch consists of 28.8per cent amylose and 71.2per cent amylopectin. Mung bean seed is highly digestible and low in antinutritional factors. It causes less flatulence than the seed of most other pulses, making it suitable for children and older people. Mung bean starch is considered to have a low glycaemic index, i.e. to raise the blood sugar level slowly and steadily. The composition of sprouted mung bean seeds per 100 g edible portion is: water 90.4 g, energy 126 kJ (30 kcal), protein 3.0 g, fat 0.2 g, carbohydrate 5.9 g, dietary fibre 1.8 g, Ca 13 mg, Mg 21 mg, P 54 mg, Fe 0.9 mg, Zn 0.4 mg, vitamin A 21 IU, thiamin 0.08 mg, riboflavin 0.12 mg, niacin 0.75 mg, vitamin B6 0.09 mg, folate 61 μg and ascorbic acid 13.2 mg. The essential amino-acid composition per 100 g edible portion is: tryptophan 37 mg, lysine 166 mg, methionine 34 mg, phenylalanine 117 mg, threonine 78 mg, valine 130 mg, leucine 175 mg and isoleucine 132 mg. Sprouting especially leads to an increased ascorbic acid concentration. Mung bean hay contains: moisture 9.7 per cent, crude protein 9.8 per cent, fat 2.2 per cent, crude fibre 24.0 per cent, ash 7.7 per cent, N-free extract 46.6 per cent, digestible crude protein 7.4 per cent, total digestible nutrients 49.3per cent. Aqueous extracts of mung bean seeds have shown in-vivo hypotensive and hepatoprotective effects in rats. Extracts from mung bean seeds and husks have shown antioxidative effects.

The chemical composition of green gram (dal) has been worked out as:

Insect Pests of Green Gram *Vigna radiata* (L.) Wilczek and Their Management 201

supplementary irrigation. In some areas where adequate early rains occur, an early-season crop can be grown before the monsoon. In semi-arid regions of Kenya with 600–800 mm rainfall evenly distributed over 2 rainy seasons, 2 mung bean crops are grown per year. In the Wei Wei Integrated Development Project in Sigor, Kenya, mung bean is grown under irrigation. In India mung bean is often sown as a fallow crop on rice land as a green

India has been universally accepted as the original home of these two pulse crops. While green gram was spread to many countries, especially in tropical and subtropical Asia, black gram has remained more or less confined to South Asia. Currently, green gram is being

India is reportedly the largest pulse growing country in the world both in terms of area as well as production covering 43.30 per cent of land area under pulses with 33.15 per cent production. In another report, it has been described that India is the largest producer and consumer of pulses in the world accounting for 33 per cent of world's area and 22 per cent of world's production of pulses. Green gram is one of the most widely cultivated pulse crops after chickpea and pigeonpea. The major producing states in India are Andhra Pradesh, Orissa, Maharashtra, Madhya Pradesh and Rajasthan accounting for about 70 per

Reliable production statistics for mung bean are difficult to obtain, as its production is often lumped together with that of other *Vigna* and *Phaseolus* spp. India is the main producer, with an estimated production in the late 1990s of about 1.1 million t. China produced 891,000 t (19per cent of total pulse production in China) from 772,000 ha in 2000. No mung bean production statistics are available for Africa. China exported 110,000 t in 1998, 290,000 t in 1999 and 88,000 t in 2000. All mung bean produced in India is for domestic consumption. In most parts of Africa where there are Asian communities, mung bean food products are

In India it is cultivated in two seasons: *kharif* and summer. However, peak market arrivals are from September to October (*kharif*) and June to July (summer). Green gram is mostly grown as a *kharif* crop (monsoon season) in the states of Rajasthan, Maharashtra, Gujarat, Karnataka, Andhra Pradesh, Madhya Pradesh and Uttar Pradesh; but, in Tamil Nadu, Punjab, Haryana, Uttar Pradesh and Bihar it is grown as a summer crop. Green gram is a short duration crop; the canopy closes in earlier than in cereal crops. Therefore, the critical period for crop-weed interference is limited to the first 30 days after sowing. However, the presence of weeds during this period may lead to 20 to 40 percent reduction in yield. The most phenomenal way of reducing weed infestation include preventive measures like use of clean crop seed and pre-planting destruction of existing weeds by tillage. In the standing crop, one inter-row hoeing and weeding at 25 to 30 days after sowing is good enough to check potential losses. Sometimes in the monsoon crop, due to incessant rains, tillage

manure (Mogotsi, 2006).

**1.6 Cultivation in India** 

grown in USA.

**1.6.1 Historical background** 

**1.6.2 Area and production** 

cent of total production.

sold in the cities (Mogotsi, 2006).


#### **1.5 Cultivation in Kenya**

Green gram is a warm-season crop and grows mainly within a mean temperature range of 20–40°C, the optimum being 28–30°C; hence, can be grown in summer and monsoon season/autumn in warm temperate and subtropical regions and at altitudes below 2000 m in the tropics. It is sensitive to frost. It is mostly grown in regions with an average annual rainfall of 600–1000 mm, but it can do with less. It withstands drought well, by curtailing the period of flowering and maturation, but it is susceptible to water-logging. High humidity at maturity causes damage to seeds leading to seed discoloration or sprouting while still in the field. Green gram cultivars differ markedly in photoperiod sensitivity, but most genotypes show quantitative short-day responses, flower initiation being delayed by photoperiods longer than 12–13 hours. The crop grows well in a wide range of soil types, but prefers welldrained loams or sandy loams with pH (5–) 5.5–7 (–8). Some cultivars are tolerant to moderate alkaline and saline soils (Mogotsi, 2006).

Green gram is propagated by seed. There is no seed dormancy, but germination can be affected by a hard seed coat. Green gram seeds are broadcast or dibbled in hills or in rows. Recommended sowing rates are 5–30 kg/ha for sole crops, and 3–4 kg/ha under intercropping. Recommended spacing ranges within 25–100 cm × 5–30 cm; whereas, for the more modern cultivars ripening in 60–75 days, maximum yields are obtained at plant densities of 300,000–400,000 plants/ha. The later-maturing traditional cultivars generally need wider spacing. Recommended spacing for sole crop of green gram in Kenya are 45 cm between rows and 15 cm within the row, with a seed rate of 6–10 kg/ha and a sowing depth of 4–5 cm. Mung bean can be grown mixed with other crops such as sugar cane, maize, sorghum or tree crops in agroforestry systems. Short-duration mung bean is often relay-cropped to make use of a short cropping period. In Kenya mung bean is usually intercropped with maize, sorghum or millet; it is occasionally grown in pure stands or intercropped with other pulses. The usual practice here is to place 1–2 rows of mung bean between rows of a cereal, or to plant mung bean in the cereal row. In pure stands, 1–2 weedings are necessary during the early stages of growth. In Kenya weeding is done using hoes and machetes. Farmers do not normally apply any inorganic fertilizer to a mung bean crop. Mung bean uses residues from fertilizer applications to the main crops in the system, though it responds well to phosphorus. Nutrient removal per ton of seed harvested (dry weight) is 40–42 kg N, 3–5 kg P, 12–14 kg K, 1–1.5 kg Ca, 1.5–2 kg S and 1.5–2 kg Mg. The nutrient removal is much higher when crop residues are removed to be used for fodder. In its major area of cultivation, the monsoon tropics, mung bean is mainly grown as a rainy season crop on dryland or as a dry-season crop after the monsoon in rice-based systems on wetland, making use of residual moisture or supplementary irrigation. In some areas where adequate early rains occur, an early-season crop can be grown before the monsoon. In semi-arid regions of Kenya with 600–800 mm rainfall evenly distributed over 2 rainy seasons, 2 mung bean crops are grown per year. In the Wei Wei Integrated Development Project in Sigor, Kenya, mung bean is grown under irrigation. In India mung bean is often sown as a fallow crop on rice land as a green manure (Mogotsi, 2006).
