Asparagus bean ( Vigna unguiculata sesquipedalis ), illustration from Blanco
|Vigna unguiculata subsp. sesquipedalis|
|( L. ) Verdc.|
The asparagus bean is an annual plant . There are bush-shaped and climbing forms with twisting tendrils . The latter are pulled on rods, wires or cords and reach heights of 2.5 to 3 m. The leaves are in three parts. In their armpits are the white, light yellow or purple flowers on 4 to 6 cm long flower stalks . Otherwise similar to the kidney bean , the flowers have a boat-shaped curved boat, not a spiral one. The flowers are self-pollinating . They open early in the morning and fade around noon. The pods are initially upright, later they hang. In Central Europe they reach lengths of 30 to 50 cm, in the main growing countries 60 to 90 cm. Young pods are cream-colored, light or dark green and have a diameter of 8 to 11 mm. Mature pods contain 10 to 30 seeds 8 to 11 mm in length. The seeds are cream, brownish or reddish in color and have a dark green ring around the navel. The thousand grain mass is 200 to 250 g.
The number of chromosomes is 2n = 22.
100 g fresh substance of the edible part of the beans contain an average of 89.0 g water, 2.8 g protein , 0.4 g fat and 3.8 g carbohydrates . The minerals contain 210 mg potassium , 50 mg calcium , 59 mg phosphorus , 52 mg magnesium and 1 mg iron . The content of vitamins is 32 mg of vitamin C , 0.13 mg of vitamin B1 , 0.11 mg of vitamin B2 and 1.0 mg of niacin . The energy value is 126 kJ (= 30 kcal).
The asparagus bean is propagated from seeds. It is pulled on trellises or poles. Bush-shaped varieties are grown especially in Asia. Market-ready pods can already be harvested 60 days after sowing. The plants produce pods well into autumn, provided the pods are harvested regularly.
The asparagus bean is sensitive to temperature and stops growing at daily highs below 20 ° C. They are sensitive to frost. Germination should take place at soil temperatures of 20 to 22 ° C. Good growing conditions are full sunlight with daytime temperatures of 25 to 35 ° C and night temperatures above 15 ° C. They tolerate periods of drought, but the pods become fibrous if it is longer dry. Annual rainfall of up to 1500 mm is favorable. They also grow in average garden soil. As typical legumes, they have a nitrogen-fixing symbiosis with rhizobia.
The young pods are prepared like those of the kidney bean . They are freshly prepared, frozen or canned. Harvest occurs when the pods are smooth and unripe and the seeds are small. They are usually sauteed or briefly seared.
Green pods are canned in Asia and Africa. In Africa, dry, ripe seeds are predominantly used.
In Southeast Asia , East and South Africa , the asparagus bean is one of the most popular vegetables. Important growing areas are China, India, Indonesia , Nigeria , Ghana, Uganda , California, Suriname and the Philippines . Cultivation in the Mediterranean region, South Africa and Australia is of lesser importance. World production was estimated at 1.25 million tons in 1990. In Central Europe , asparagus beans are grown to a small extent in greenhouses, for example in the Netherlands.
The asparagus bean emerged from the originally African cowpea . This must have happened in Asia. It is grown today in many tropical lowland areas. In the 16th century it came to the West Indies , around 1700 to today's USA.
- Georg Vogel: Handbook of special vegetable cultivation. Verlag Eugen Ulmer, Stuttgart 1996, ISBN 3-8001-5285-1 , pp. 674-678. (Features, use)
- National Research Council: Lost Crops of Africa: Volume II: Vegetables. The National Academies Press 2006, ISBN 0-309-10333-9 , pp. 222-233. (online) (cultivation, use).