GREEN GRAMS) (Vigina spp) Manual


Introduction

Green gram is an erect annual plant which grows to a height of 60-70 cm tall. Pods  contain 10 to 15 seeds each. Each plant typically produces 30 to 40 pods which turn darker in colour as they mature.

Nutritive value

Green grams lie in the class of high and easily digestible protein. It contains approximately 24% protein, 1.2% fat, 16.3% dietary fiber, 4.5-5.5% ash and 63% carbohydrates on dry weight basis. Lysine values are comparatively large and thus green grams is an excellent complement to rice. Green grams also contain thiamin, iron and magnesium.

Ecological requirements

Altitude

Best altitudes is between 50-1600 metres above sea level

Rainfall

An annual rainfall of 650mm is adequate.  The most critical stage in moisture requirement is from flowering to pod filling. High humidity and excess rainfall late in the season can result in disease problems and delayed maturity. Heavy rainfall and cool temperatures lead to increased vegetative growth with reduced pod setting and development.

Soil type

Green grams perform best on fertile, sandy loam soils with a pH range of 6.3 – 7.2. Root growth gets restricted on heavy clay soils leading to poor yields. The crop does not tolerate saline soils and can show severe iron chlorosis and other micronutrient deficiencies on highly alkaline soils.

Temperature

Optimum temperature range is between 27 and 30 °C

2.1.1  Varietal Selection

Two main varieties can be differentiated depending on the colour of the seeds. The yellow and the green. The local green grams variety is small and ripens unevenly while. The improved varieties have bigger seeds and tends to ripen uniformly.

Table 1: Mung bean variety characteristics

Variety/

Description

Seed  Colour Maturity Yields
N22 or KVR 22 Golden yellow seeds 80-90 days 400-600 kgs/acre
N26 or KVR-26

(Nylon)

Shiny green seeds 60 to 65 days 500 – 800kg/acre

KS20

Dull green seeds

80-90 days

650 – 900kgs/acre

Fertilizers and manure

100 kg DAP/ha and 10 to 20 tons (200 wheel barrows per acre) farm yard manure can be applied,.

Planting

Seeds should be planted 4 cm deep in a well-prepared seedbed with good moisture content. If the surface layers are dry, this depth should be increased to 7.5 cm but only if the soils do not crust easily.

Spacing

For pure stand the spacing should be at 45cm x 15cm. In intercrop, green gram rows are planted in the middle of the accompanying crop and the intra row spacing is maintained at 15cm.

Seed rate

10-15kg/ha or 4-8kg/acre

Weeding

The first weeding should be done 2 weeks after emergence and the second weeding before flowering. Herbicides are applied before the grams emerge.

Common insect pests and their management

Insect Damage Symptoms Management
Bean fly Leaves droop, yellow and dry up. Stem swells and cracks open Early planting, dressing seeds, crop rotation
Thrips

 

Flower shedding before opening. In case of severe incidence shriveled grains produced.

.

Intercrop with cotton.
Bean Aphids Distortion of leaves, stunting of plants and poor nodulation of roots Spray with endosulphan 35 EC (2ml/l)
Whitefly Plants become  weak and die in severe attack. Grow maize, sorghum or pearl millet as a barrier crops. Grow cotton between the rows one month earlier as a trap crop
Bruchid beetle A storage pest. Infested grain show  holes in the seeds and a whitish larva or pupa can be found inside.  Harvest before the pods shatter.

Dry grains to 10% mc and stores should be cleaned.

2.2.7 Disease management

Disease Symptoms Control
Powdery Mildew White powdery coating on leaves, stems

and pods. At advanced stages, the color of the powdery mass turns dirty white.

Destroy diseased plants.
Yellow Mosaic Yellow mosaic spots, which increase with time leading to complete yellowing. Reduced flowering and pod development. Early infection often to death of plants. Rogue out  diseased plants to prevent further spread of the disease.

Cercospora Leaf Spot

Spots on petioles, stems and pods. During favorable condition the spots increase in size

Crop rotation and destroy infected crop debris. Remove  alternative  crop  hosts .

Anthracnose Circular brown sunken spots with dark centers and bright red orange margins on leaves and pods. The diseased plants should be uprooted and destroyed

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Harvesting

Mung bean pods are thin and brittle when dry so shattering can be a problem during harvesting. Harvesting should take place when most of the pods have turned black. Pods should be picked individually or whole plants can be uprooted and dried for about 2 to 5 days. Prior to threshing, dry the pod because high moisture will damage the seed. The moisture can be tested by crushing a few grains with the teeth or pinching with fingers. If the seed is easily crushed, the moisture is still too high and dry further.              After threshing the seed is dried again the mc is 12%

Storage

The grains should be dusted using different formulations of storage dusts at rates of 50gm per 90 kg bag. Such formulations include Actelic super 50gm/90kgs,   Skana super dust 50gm/90kgs, Spintor laclan 50gm/90kgs, Blue cross/Malathion 50gm/90kgs.  Packaging should be done in airtight bins, silos or hermetic bags. Ordinary 90kg polythene bags can also be used