Chi = red, adzuki bean ≠ red adzuki bean? ?

Are you confused about the difference between adzuki beans and red beans? Because they are close relatives.

The scientific names of adzuki bean and red bean are red bean and rice bean respectively. Both belong to the Vigna genus and the Vigna subgenus, and their production areas are mainly distributed in Asia. They are both typical "Asian crops".

The reason why it is difficult to tell the difference is that most of the adzuki beans and rice beans on the market are red, so they are also called "red beans", such as red bean porridge, red bean rice, red bean and barley water, etc. In fact, in addition to red, adzuki beans and rice beans also have yellow-white, black, green, spotted, and civet colors (Figure 1, Figure 2).

Figure 1. Adzuki beans with different seed coat colors

Figure 2 Rice beans with different seed coat colors

So as close relatives, what are the differences between adzuki beans and rice beans, and how can we distinguish them?

First of all, in terms of grain shape, adzuki bean grains are short elliptical or short cylindrical, while rice beans are elongated elliptical, as if the adzuki bean grains were squeezed and stretched, similar to long-grain rice. This is the main reason why rice beans are translated into rice beans (Figure 3).

Figure 3 Seeds of adzuki beans (left) and rice beans (right) (grain shape and hilum)

Secondly, from the perspective of the hilum, the hilum of adzuki beans is slender and not obvious, while the hilum of rice beans is protruding and divided into two halves with a groove in the middle (Figure 3).

Third, judging from the true leaves, the true leaves of adzuki beans are nearly round, while the true leaves of rice beans are mostly slender (Figure 4).

Figure 4 True leaves of adzuki beans (left) and rice beans (right)

Fourth, from the perspective of pod shape, the pods of adzuki beans are mostly yellow-white, relatively thick and short, and mostly straight-cylindrical, while the pods of rice beans are mostly yellow-brown, relatively slender, and mostly sickle-curved, with long and pointed beaks (Figure 5).

Figure 5 Mature pods of adzuki beans (left) and rice beans (right)

Fifth, from the perspective of medical and health care, both have the effects of removing dampness, reducing swelling and promoting diuresis, but Chinese medicine prefers rice beans, namely adzuki beans; while the red bean and coix seed porridge on the market mostly uses adzuki beans.

Sixth, from the perspective of production areas, adzuki bean production is mainly distributed in China, Japan, and South Korea, while rice bean production is mainly distributed in Southeast Asian countries such as Myanmar, Thailand, Vietnam, and southern provinces of my country.

In addition, judging from the breeding achievements, adzuki beans have good upright plants and low pod bursting tendency, so they can be harvested in one go; rice beans have strong vine growth and large biomass, and can grow up to 3 to 4 meters high in the north. They are prone to pod bursting after maturity and need to be harvested manually in batches.

About the Author

Wang Lixia, female, from Ganyu, Jiangsu, PhD, researcher, member of Jiusan Society, doctoral supervisor. Post scientist of the National Edible Bean Industry Technology System, director of the Chinese Society of Crop Science, secretary-general of the Edible Bean Professional Committee, director of the Chinese Society of Atomic Energy Agriculture, and director of the Genetic Resources Branch of the Chinese Society of Agronomy. She joined the Institute of Crop Sciences, Chinese Academy of Agricultural Sciences in July 2005, and is mainly engaged in the collection, preservation, evaluation, identification, and innovative utilization of edible bean germplasm resources. She has successively presided over projects such as the National Natural Science Foundation, national key research and development, and international and inter-provincial cooperation. She has published more than 70 papers in Chinese journals such as "Agronomica Sinica", "Journal of Genetics", and "Chinese Agricultural Science", and more than 40 papers in English journals such as Nature Communication, Frontier in Genetics, Molecular Breeding, Journal of Plant Research, and Crop Science. She has won the first prize of China Agricultural Science and Technology (3), the Popular Science Award (2), the first prize of Jiangsu Science and Technology (3), and the first prize of Outstanding Achievements of the Chinese Academy of Agricultural Sciences (5).