Database Research Summaries
Agronomic Evaluation of USDA Heat-Tolerant Maturity Group III

calendar_today Year of Research: 2017
update Posted On: 12/04/2019
group John Orlowski (Project Leader, Mississippi State University – DREC)
bookmark Mississippi Soybean Promotion Board

Research Focus

The focus of this research project is to agronomically and economically evaluate heat-tolerant MG III soybean genotypes that have been recently developed by the USDA-ARS, as well as commercially available MG III soybeans.


  • Compare productivity and grain quality of three newly developed ARS late MG III soybean lines to three traditional late MG III soybean cultivars.
  • Compare narrow row to wide row soybean production for MG III varieties.
  • Examine the economic considerations of the using both commercially available and USDA-bred MG III soybeans.


  1. When data were averaged over variety and row spacing, soybean yields were higher with late planting date in both years, likely due to delayed emergence for the May planting date and to very dry weather conditions coupled with dry soil at planting.
  2. Seed yield of DS 65-1 was significantly lower than that of all other varieties for both planting dates used in this study. No yield differences were observed for varieties in 2017.
  3. When averaged across varieties and planting dates, narrow row spacing (20 in.) increased soybean yield by 3.6 bu/acre compared to soybeans planted on wide rows (40 in.) only in 2016.
  4. An interaction between row spacing and planting date in 2017 showed that soybean yields were 12.2 bu/acre greater with wide row spacing than with narrow row spacing for the late planting date. No differences were observed for yield due to row spacing for the early planting date in 2017.


  • Using MG III varieties could allow dryland producers to sell their soybean into the old crop market and receive a premium for their crop.
  • If the yield of the USDA varieties is similar to that of commercial varieties, the resulting increase in seed quality can result in soybean growers receiving little or no dockage at elevators.
  • Yields can be significantly improved if the use of MG III varieties could allow dryland farmers to harvest soybean before the onset of summer drought.


For more information about this research project, please visit the National Soybean Checkoff Research Database.

Funded in part by the soybean checkoff.