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Publication #HS1268

Long Bean—an Asian Vegetable Emerging in Florida1

Kshitij Khatri, Guodong Liu, Qingren Wang, Yuncong Li, David Dinkins, and Bonnie Wells2

Food diversity, nutritional food supply, and profitability are the priorities of agricultural and horticultural industries. To diversify vegetable products and increase the Florida vegetable industry’s competitiveness, a number of new vegetable crops are rapidly emerging in the state. For example, there are more than 20 Asian vegetable crops, such as luffa (Luffa cylindrica (L.) Roem), shalihon (Brassica juncea (L.) Czern), and tahn ho (Chrysanthemum coronarium L.), grown across Florida. Due to Florida’s favorable climate, these vegetable crops grow well and have high market potential. The objective of this article is to provide a general overview on one of the Asian vegetable crops grown in Florida, long bean.

Long bean (Vigna unguiculata subs. sesquipedalis, Family: Fabaceae) is a leguminous vegetable crop with climbing vines that produce long pods consumed as a cooked vegetable. It is a popular crop in Asian countries such as in China. The subspecies name, “sesquipedalis”, means “one-and-half-foot long” and is an approximation of the pod length. It is also known as asparagus bean, Chinese long bean, long-podded cowpea, and yardlong bean. Long bean is called as bora, bodi, pea bean, and snake bean. This vigorous annual crop is a member of the genus Vigna, which is different from the common bean, which belongs to the genus Phaseolus.

This crop was recorded in Chinese literature as early as the Song Dynasty in 1008 CE, though China as the origin of long bean is not completely established. This crop is also considered to have originated from tropical Africa because wild species of Vigna can be found there (Yamaguchi 1983).

Long bean has two cotyledons (seed leaves), a significant part of the seed, and so is a dicotyledonous species. As an annual climbing vine crop, it has the following morphological (structural) features: purple or black colored kidney-shaped seeds (Figure 1) at maturity, two cotyledons (Figure 2), 3 to 4-inch-long trifoliate (divided into three leaflets) leaves with ovate (egg-shaped) leaflets (Figure 3); and violet or yellow flowers (Figure 4). This crop requires cross-pollination, usually by bees or other insects (Figure 5). The green, straight or irregularly twisted, limp pods are usually 2 to 4 feet long (Figures 4–7) (Duke 1981). There are two types of long beans: light green (Figures 4 and 5) and dark green (Figure 7). As a leguminous crop, it has the ability to fix atmospheric nitrogen. Root inoculation with the nitrogen fixing bacteria Rhizobium can improve root nodule formation and reduce nitrogen fertilizer dependence.

Figure 1. 

Seeds of long bean.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Figure 2. 

The cotyledons and true leaves of long bean seedlings.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Figure 3. 

Fully developed leaves of long bean.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Figure 4. 

Flowers of long bean.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Figure 5. 

Pollination of long bean is mediated primarily through bee activity.


Credit:

Kshitij Khatri, UF/IFAS


[Click thumbnail to enlarge.]

Figure 6. 

Long bean plants bearing pods in Hastings.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Figure 7. 

White yardlong pods developing on long bean vines grown in Hastings in fall 2015.


Credit:

Guodong Liu, UF/IFAS


[Click thumbnail to enlarge.]

Figure 8. 

Long bean pods growing in Miami-Dade County.


Credit:

Qingren Wang, UF/IFAS


[Click thumbnail to enlarge.]

Figure 9. 

Dark green pods of long bean.


Credit:

Qingren Wang, UF/IFAS


[Click thumbnail to enlarge.]

Long Bean Can Be Grown Twice a Year in Florida

Florida has a favorable climate for producing long bean. It can be grown in north Florida in both spring and fall. The spring season starts in early March and ends in late July. The fall season begins in late July and finishes in mid-November. In south Florida, such as in Miami-Dade, long bean is grown from September or October through April and is harvested multiple times. Generally speaking, the fall growing season in north Florida is more profitable because many competitors in some states in the north are unable to grow this crop in open fields and thus compete with Florida growers.

Long bean can be grown in a wide range of soil types from sandy loam to clay. The crop can tolerate a broad range of soil pH; however, recommended pH for best growth is 5.5–6.5. Long bean is a suitable crop for arid and semi-arid growth conditions because it is able to tolerate high heat, humidity, and drought stress. The crop grows well in warm climates with average monthly temperatures of 68 to 86 oF. Its preference for heat to germinate and grow makes it a suitable crop throughout the southeastern United States. However, plant growth is adversely affected by water logging, cold temperatures, and frost (Duke 1981). In south Florida, the extremely high humidity during the hot, rainy summer season often makes long bean susceptible to powdery mildew (Wang et al. 2014).

Planting

Long bean seeds can retain their viability for several years if they are kept in seed storage. This crop can be either transplanted or directly seeded. The seedlings can be transplanted when they have developed two true leaves. Transplanting allows earlier crop establishment and expands the growing season but also requires more labor. In Florida, direct seeding is the more common practice. The seeds are planted approximately 2 inches deep on raised beds with plants spaced 3 feet apart and beds space 6 feet apart. Plants can grow 9 to 12 feet tall, so a trellis support is needed. A trellis system of 6 feet height provides a good support for the climbing vines and facilitates harvesting (Lawrence 2012).

Fertilizer Application

This is a new crop in north Florida. There is no IFAS fertilizer recommendation yet, but IFAS is working on this crop. Before the IFAS recommendation becomes available, growers can apply fertilizers based on other leguminous crops such as snap bean, lima bean, and pole bean.

Harvesting

Long beans are ready to harvest 40 to 70 days after seeding, depending on location. This crop should be harvested at an immature stage when seeds are not fully matured. It is manually harvested on a daily basis when the pods are 10 to 12 inches long. Alternatively, it can be harvested as dried beans after seeds are fully developed and matured. Young leaves can be used to feed livestock, and the plant’s large, attractive violet flowers with draping pods can serve as an ornamental plant in urban parks and gardens (Lawrence 2012).

Long Bean Is a Good Source of Human Nutrition

Long bean is a good source of protein, vitamin A and C, thiamin, riboflavin, and mineral nutrients including iron, magnesium, manganese, phosphorus, and potassium (Table 1).

Further Information

Coker, C., M. Ely, and T. Freeman. “Evaluation of Yardlong Bean as a Potential New Crop for Growers in the Southeastern United States.” HorTechnology 17 (4): 592–594.

Duke, J. A. 1981. Handbook of Legumes of World Economic Importance. New York: Plenum Press.

Lawrence, J. H. and L. M. Moore. 2012. Plant Guide: Yardlong Bean. USDA Natural Resources Conservation Service. Accessed October 1, 2015. http://plants.usda.gov/plantguide/pdf/pg_viuns2.pdf

US Department of Agriculture (USDA). “Yardlong bean, raw.” Accessed October 1, 2015. http://ndb.nal.usda.gov/ndb/foods/show/2988?manu=&fgcd=

Wang, Q., S. Zhang, and T. Olczyk. 2014. Management of Powdery Mildew in Beans. PP311. Gainesville: University of Florida Institute of Food and Agricultural Sciences. Accessed October 1, 2015. https://edis.ifas.ufl.edu/pp311

Yamaguchi, M. 1983. World Vegetables: Principles, Production and Nutritive Values. Connecticut: A VI Publishing Company Inc.

Tables

Table 1. 

Nutrient value per 100 g (3.5 oz) of raw long beans (USDA-ARS)

Nutrient

Unit

A serving

1 cup slices

1 pod

   

(100 g)

% daily value

(91 g)

% daily value

(50 g)

% daily value

               

Water

g

87.85

 

79.94

 

43.93

 

Energy

kcal

47

 

43

 

23.50

 

Energy

kJ

197

 

179

 

98.50

 

Protein

g

2.8

 

2.55

 

1.40

 

Total lipid (fat)

g

0.4

 

0.36

 

0.20

 

Ash

g

0.6

 

0.55

 

0.30

 

Carbohydrate, by difference

g

8.35

 

7.6

 

4.18

 

Minerals

             

Calcium, Ca

mg

50

5

46

4.6

25.00

2.50

Iron, Fe

mg

0.47

4

0.43

3.6

0.24

2.00

Magnesium, Mg

mg

44

12

40

10.9

22.00

6.00

Phosphorus, P

mg

59

8

54

7.3

29.50

4.00

Potassium, K

mg

240

5

218

4.6

120.00

2.50

Sodium, Na

mg

4

 

4

0.0

2.00

0.00

Zinc, Zn

mg

0.37

4

0.34

3.6

0.19

2.00

Copper, Cu

mg

0.048

 

0.044

0.0

0.02

0.00

Manganese, Mn

mg

0.205

10

0.187

9.1

0.10

5.00

Selenium, Se

µg

1.5

 

1.4

0.0

0.75

0.00

Vitamins

             

Vitamin C, total ascorbic acid

mg

18.8

23

17.1

20.9

9.40

11.50

Thiamin

mg

0.107

9

0.097

8.2

0.05

4.50

Riboflavin

mg

0.11

9

0.1

8.2

0.06

4.50

Niacin

mg

0.41

3

0.373

2.7

0.21

1.50

Pantothenic acid

mg

0.055

11

0.05

10.0

0.03

5.50

Vitamin B-6

mg

0.024

2

0.022

1.8

0.01

1.00

Folate, total

µg

62

16

56

14.6

31.00

8.00

Vitamin B-12

µg

           

Vitamin A, (Retinol Activity Equivalents)

µg

43

5

39

4.6

21.50

2.50

Retinol

µg

0

0

0

 

0.00

 

Vitamin A, IU

IU

865

 

787

 

432.50

 

Vitamin D (D2 + D3)

µg

0

 

0

 

0.00

 

Vitamin D

IU

0

 

0

 

0.00

 

Lipids

             

Fatty acids, total saturated

mg

105

 

96

 

52.50

 

Fatty acids, total monounsaturated

mg

36

 

33

 

18.00

 

16:1 undifferentiated

mg

1

 

1

 

0.50

 

18:1 undifferentiated

mg

21

 

19

 

10.50

 

22:1 undifferentiated

mg

13

 

12

 

6.50

 

Fatty acids, total polyunsaturated

mg

169

 

154

 

84.50

 

18:2 undifferentiated

mg

96

 

87

 

48.00

 

18:3 undifferentiated

mg

70

 

64

 

35.00

 

Cholesterol

mg

0

 

0

 

0.00

 

Amino Acids

             

Tryptophan

mg

32

 

29

 

16.00

 

Threonine

mg

104

 

95

 

52.00

 

Isoleucine

mg

150

 

136

 

75.00

 

Leucine

mg

200

 

182

 

100.00

 

Lysine

mg

184

 

167

 

92.00

 

Methionine

mg

40

 

36

 

20.00

 

Cystine

mg

42

 

38

 

21.00

 

Phenylalanine

mg

154

 

140

 

77.00

 

Tyrosine

mg

115

 

105

 

57.50

 

Valine

mg

162

 

147

 

81.00

 

Arginine

mg

196

 

178

 

98.00

 

Histidine

mg

90

 

82

 

45

 

Footnotes

1.

This document is HS1268, one of a series of the Horticultural Sciences Department, UF/IFAS Extension. Original publication date October 2015. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Kshitij Khatri, biologist; Guodong Liu, assistant professor; Horticultural Sciences Department; Qingren Wang, Extension agent, UF/IFAS Extension Miami-Dade County; Yuncong Li, professor, Soil and Water Science Department, Tropical Research and Education Center; David Dinkins, Extension agent, UF/IFAS Extension Putnam County; and Bonnie Wells, Extension agent, UF/IFAS Extension St. Johns County; UF/IFAS Extension, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.