Modifications of Optimum Adaptation Zones for Soybean Maturity Groups in the USA

Abstract

Soybean cultivars are generally adapted within a narrow north‐south geographical zone for full‐season growth due primarily to photoperiod response. The areas of adaptation were empirically defined more than three decades ago and re‐examination is needed. The accuracy of adaptation area determination can be improved by utilizing updated information, including changes in production practices and new technologies. The objective of this paper was to use current soybean yield data from experiments conducted across soybean producing states in the US to develop optimum zones of adaptation for soybean maturity groups (MGs) in the continental US. Data from state soybean variety trials conducted in 1998‐2003 were obtained from 139 locations, and were used to create regional adaptation map using ArcGIS. The MG 0 cultivars are adapted best to the region north of latitude 46°N, whereas succeeding groups are adapted further south. Each of the MGs 0 to III is adapted best within approximately two degrees latitude covering an area equivalent to 220 km wide from north to south. The zones of adaptation for MGs IV, V, and VI are wider than those for the earlier maturing cultivars. Overall, the regions of adaptation for the early‐maturing cultivars (MG 0 to III) have not changed; however, the adapted zones for MGs IV, V, and VI are much broader than previously thought. Groups VII and VIII, which dominated production areas in the South decades ago are now planted on a limited basis.

Delineating Soybean Maturity Groups across the United States

“…These results are somewhat similar to Zhang et al (2007) who reported that MG 0 or earlier are better suited North of latitude 46°N including northern Wisconsin and Michigan using a different dataset (139 sites). Results from our study suggest that MG 0 should be restricted to North Dakota and northern Minnesota.…”

“…Results from our study suggest that MG 0 should be restricted to North Dakota and northern Minnesota. Also, Zhang et al (2007) used convex parallel lines to delineate optimum MG regions and they continued the lines to the western regions of the High Plains states (North and South Dakota) where there was a lack of trial data. Our updated map uses vastly more data, different methodology in data analysis, and extends the trial locations beyond those Zhang et al (2007) used.…”

“…More recently, Zhang et al (2007) redefi ned the optimum MG zones using yield variety trial data from 1998 to 2003. Th ese authors found that adaptation regions for varieties with MG = 0 to 3 have not changed whereas, for varieties MG = 4 to 6 adaptation zones are much broader than those proposed by Scott and Aldrich.…”

Modelling soybean yield responses to seeding date under projected climate change scenarios

“…The cultivar AC Bravor belongs to Maturity Group (MG) 0 and AC Harmony to MG 00. Based on the characteristics of the timing of flowering and maturity and its geographical adaptation, soybean has been classified into 13 MG from 000, 00, 0, 1… to 10 with an increasing life cycle (Cober and Voldeng 2001;Zhang et al 2007). Soybean cultivars of MG 000, 00, and 0 are the earliest in maturity and are mainly adapted to southern Canada.…”

Stability of Soybean Genotypes and Their Classification into Relative Maturity Groups in Brazil

“…In the United States, a rating system has been developed, ranging from Group 00, in the northern region of the country, to Group VIII, in the southern region of the country [3]. The adaptation range of each American maturity group is between 200 and 300 km, following a north-south axis in the territory [4].…”