The maturity date of soybean Glycine max L. A total of world soybean varieties, including 48 MG checks, were tested at a major site Nanjing, Soybean maturity groups The maturity date of the world soybean varied greatly 75— d in Nanjing. The cluster analysis among MGs and subgroups using genome-wide markers validated the MG sequential emergence order and the subgroup differentiation in eight MGs.
For future evaluation, in addition to one major site Nanjingone supplementary southern site Nanning and one supplementary northern site Heihe are sufficient. Soybean Glycine max L. Soybean is rich in nutritional value due to its high protein and oil content as well as aspects of its functional composition, such as isoflavones. Along with its dissemination worldwide, soybean has adapted to diverse ecological conditions, especially to the local day length and temperature conditions created by geographic latitude and altitude.
The most significant trait related to adaptation to diverse environments is growth period, or maturity date. Originally, soybean was a short-day crop with a sensitive response to photoperiod, as well as temperature.
Because day length changes with the seasons, Soybean maturity groups season is another ecological factor determining the maturity date of soybean. The maturity date varies greatly among soybean varieties around the world, even within a same geographic region. Initially, farmers and early soybean scientists classified soybeans as early, medium and late maturity types.
This classification was extensively used everywhere. However, it was insufficient at comparing varieties from different ecological regions.
An early maturing variety in one region may be considered a late variety in another region. Ultimately, 13 MGs, i. MG00, 0, I, X, Soybean maturity groups formed in the world.
The difference in maturity date between two adjacent groups is approximately 10 to 15 days in an adapted area Norman Categorizing soybeans into different MGs allows for more accurate and quick judgment of the prospects for introducing new varieties and plays an important role in the breeding and production of soybeans in North America. Many soybean scientists in different countries have adopted this MG system and have classified their local varieties into different MGs.
Monsanto was the first company to introduce the concept of maturity groups to Brazil Penariol As an increasing number of private companies used the North Soybean maturity groups system, the traditional Brazilian method of classifying varieties into early, medium and late was gradually replaced with the MG system and was classified into MG VI—VIII.
In China, the traditional way of grouping soybeans was also early, medium and late, relative to a local area and even to the cropping system Hao et al. In addition, they found that the significant difference in flowering date was related to geographic locations Soybean maturity groups cropping systems in MG 0, I, II and Soybean maturity groups and divided each group into two subgroups according to the days to R1 beginning bloom.
It seemed that the early maturity group continued to increase as the soybean area expanded northward and new varieties developed.
According to the trials at nine locations in Northeast China, Fu et al. Fukui and Arai studied the ecological classification Soybean maturity groups soybean varieties in Japan based on the days from germination to blooming and from blooming to ripening with special reference to their geographical differentiation. They grouped soybean varieties into five vegetative stage groups and three reproductive stage groups in a total of nine combined groups.
The growth period structure differentiation among varieties was also studied in Soybean maturity groups Sun et al.
They found that a different structure of growth periods existed within each group of MG 0—III and further divided them into two subgroups: However, no study has been carried out to evaluate the variation of MG of the worldwide soybean varieties under a uniform environment, due to the extreme diversity of the sensitivity to day length and temperature. The present study aimed to reveal the variation of MGs of the world soybean varieties under a uniform environment Nanjing, China in this study and the distribution of MGs in world geographic regions.
The first Soybean maturity groups was to establish a procedure to identify diverse MGs for a large number of varieties, i. According to our previous experiences in identifying the MGs of Chinese soybeans Gai et al. The knowledge of the world MG expansion and geographic distribution will benefit both the development of Soybean maturity groups varieties and the exploration of the evolutionary processes of growth period traits.
According to the dissemination paths described by Singh and Hymowitz Soybean maturity groups, they were further divided into 13 geographic populations: MG types of world soybean varieties distributed in 13 geographic populations including 48 MG checks. The field experiments were set in five locations: Table 1 shows the entire experimental scheme with the MG checks arranged. The field tests at the major site of Nanjing and its supplementary site of Jining were conducted in two years. Here, spring planting was used for Soybean maturity groups the full season response of the materials rather than the local summer planting which is the regular double cropping system after winter wheat.