Research Highlights

Research Highlights
Yield Potential of Commercial Varieties Under Drought: Identifying and Overcoming Weakness Via the Public Breeding Pipeline

Figure 1. Soybean field in South Carolina, 2019. Yield was 10 b/acre.

By Dr. T. E. Carter. Jr.; USDA-ARS; Raleigh, North Carolina

Summer drought has always been the most important barrier to profitable soybean production. Irrigation is expensive — only about 8% of the U.S. soybean acreage is irrigated. A solution is to create new, drought-tolerant varieties of soybean. To that end, a $465,002 grant was provided to Team Drought to create a national public breeding pipeline of novel, drought-tolerant varieties and breeding stocks. 

Surprisingly, private-sector breeders are not pursuing a coordinated attack on drought. Studies from 15 years ago suggest that private-sector varieties generally wilt fast when drought hits. More recent evaluations in 2016-2018 confirm this is still the case. Less than 15% of current private varieties of soybean show some level of drought tolerance. 

New genetics and genome sources are needed. Team Drought evaluated thousands of varieties from around the globe, and identified a select few with good levels of drought tolerance. These novel Asian soybeans are being hybridized with local U.S. varieties to produce the first drought-ready varieties. Breeding and development is taking place at special drought-prone field sites in North Carolina, Georgia, South Carolina, Arkansas, Missouri and Kansas. 

Figure 2. Experimental drought plots, North Carolina, 2019.

After screening thousands of exotic soybean types from around the world, the first drought-tolerant, slow-wilting soybean was discovered in the 1980s in Japan (PI 416937). Two more were discovered in the 1990s in Nepal and Korea (PI 471938 and PI 407859-2). In recent years, more drought-tolerant soybeans have been identified in China and Sweden. These exotic drought-tolerant types are the foundation of the USB’s Public Breeding Pipeline for Drought-Tolerance. 

Slow-wilting adapted breeding lines coming out of this pipeline appear to be drought-tolerant, with yield response as much as 3 to 8 bushels/acre, depending on the severity and timing of the drought. This yield boost associated was observed in North Carolina, South Carolina, Missouri and Kansas. 

Figure 3. Comparison of soy with slow wilt trait on right to soy without the trait on left. 

The first drought-tolerant variety, USDA-N8002, was released in 2015, as well as two germplasms, R10-2436 and R10-2710, more recently. Many more breeding lines are in the pipeline and are candidates for release in the near future.

In September, more than 10 commercial breeders from BASF, Pioneer and Bayer visited the drought-testing site at the Sandhills Research Station, located near the Pinehust golf courses in North Carolina. Commercial breeders got a firsthand look at USB’s public breeding pipeline. Drought was severe, and the new drought-tolerant materials showed themselves well. An impromptu “in the field” brainstorming session developed on methods to put the new lines to good private-sector use. 

To date, one commercial variety has been released, and many more are in the pipeline. These new stocks are not only available to growers, but they can also be used as commercial breeding stock by private breeders. By encouraging commercial use of these genetic materials, deployment of drought tolerance across the industry will be maximized, and the entire value chain will benefit.

Published: May 15, 2020

The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.