Short-Season Soybeans for Saskatchewan - Pulse Research

July 03, 2019

Short-season soybeans represent a huge opportunity for pulse growers in Saskatchewan, but as with any new crop, there are a lot of hurdles to overcome and that will only happen with targeted research investment.

It is part of Saskatchewan Pulse Growers’ (SPG) strategy to ensure pulses are a profitable and sustainable crop option for every grower in this province. Fostering the development of soybeans so that they become a consistently profitable option is definitely part of that effort.

Soybeans have been grown in Eastern Canada for many years however, there is still much to learn about growing the short-season varieties in the West. This is particularly true in Saskatchewan where acres are increasing as a new crop option. Farmers and researchers alike would love to know more about the mechanisms behind yield formation in these shorter, colder, drier seasons, if nitrogen fixation is different here than in the East, or even just have better insight into what works and what does not for these unique varieties.

“We do not know a lot about short-season soybeans because they have not been around for long,” says Dr. Diane Knight, Professor in the College of Agriculture and Bioresources at the University of Saskatchewan (U of S). “Everyone assumed that they would perform just like the long-season varieties we are more familiar with, but they do not.”

Knight is one of four principal researchers heading up a number of SPG-funded studies that aim to fill in some fairly large knowledge gaps concerning short-season soybeans.

The projects (some which began in the spring of 2018 and will run for up to five years) support and overlap with each other in a collaborative effort that is truly impressive. One researcher’s findings can help inform another’s to build a more complete picture of short-season soybeans and, in five years’ time, this research will provide the tools for more successful and consistent short-season soybean production.

Nitrogen and the Short Season

Knight is looking at how the nitrogen cycle is different for short-season soybeans. Specifically, she wants to measure biological nitrogen fixation and nitrogen uptake in a number of short-season soybean varieties and how that translates into protein content in grain and residue.

The impetus for this research is that short-season soybean varieties have a lower percentage of seed protein than their longer season counterparts and no one quite knows why.

“There is some evidence from research in the United States that the nitrogen found in the seed protein preferentially comes from nitrogen fixation, so from the atmospheric nitrogen the plant fixes and not the fertilizer we put down with the seed,” says Knight. She explains that it takes more energy for the plant to fix nitrogen than to take it up, so one of the things she is looking at is whether or not biological nitrogen fixation is able to supply enough nitrogen to achieve optimal nitrogen content in the grain, or seed.

“We know soybeans are a decent nitrogen fixer and I am trying to find out if biological nitrogen fixation is a limiting factor for protein development,” she says. “What I think might be happening is that the shorter season just does not give them enough time to build protein in the seed.”

Knight’s research will be looking at nitrogen uptake rates at different growth stages, the impact of cold temperatures on biological nitrogen fixation, and examining nodules to see what rhizobia are present there, and where they came from – applied inoculant or natural populations. “We want to know who is getting into the nodules and fixing nitrogen,” says Knight. “How good are the ones we are introducing compared to the rhizobia already there?”

Beating the Cold

Knight will be piggybacking some of her work on the soybean plots of Dr. Rosalind Bueckert, Professor in the Department of Plant Sciences at the U of S, who is looking at the physiology of yield formation and beating the cold in northern latitude soybeans.

“We will be looking at 24 genotypes of soybean, including conventional and Roundup Ready^® types,” she says. All are in maturity group 00 and 000 and there will also be a subset of new short-season varieties from Dr. Leonid Savitch’s program in Ottawa.

“Part of this project will be to do some very accurate growth staging,” says Bueckert, adding that there is next-to-no published research on short-season soybeans, so farmers have limited information when it comes to variety selection.

“The number one thing that confuses everyone is heat units,” she says. “One thing soybeans do when they get under stress is stop growing, but they still accumulate heat units.” How heat unit ratings translate to actual field performance in a region where cold and short days might be limiting factors is something Bueckert wants to find out.

Her project will look at how cool temperatures affect yield formation processes in short-season soybeans. These processes include flowering patterns (days to flowering, duration, maturity, yield, and number of nodes) as well as plant growth and development characteristics, such as pods per node, seeds per pod, and seed size, all of which impact yield.

The end goal is to figure out how cool temperatures and other abiotic stressors affect yield formation and identify key traits for varietal improvement. Bueckert indicated that, to date, there has been an emphasis in trait development on herbicide resistance, but knowing what traits govern cold and stress tolerance could open some new possibilities.

Research into short-season soybeans adapted to Saskatchewan’s growing conditions provides another crop for growers to add to their rotation.

Protecting the Roots

As soybean acreage grows in the west, many of the root diseases that are prevalent in Eastern Canada are beginning to appear here and Dr. Debra McLaren, a Crop Production Pathologist with Agriculture and Agri-Food Canada (AAFC) in Brandon, is leading a research project looking at this issue. “Having another crop in the rotation is important,” says McLaren. “The big thing with any new crop coming in are diseases, like root rots.”

The work involves a national study on root diseases of soybeans with the goal of providing farmers with better management tools and options. Along with SPG, this project is supported by the Canadian Agriculture Partnership and the Manitoba Pulse and Soybean Growers.

Take Phytophthora. “We started to see it here in 2013, and in 2014 we started to figure out what races we were looking at here,” she says. McLaren and her team are identifying which races are predominant in the West so growers can select soybean cultivars with appropriate resistance, and so breeders can develop cultivars that are resistant to new races of Phytophthora. Other team members are also identifying Phytophthora races in Eastern Canada.

McLaren’s project also involves surveys of Fusarium, Rhizoctonia, and Pythium spp. as well as soybean cyst nematode. It will also monitor the spread of sudden death syndrome in Ontario and set up a sudden death syndrome nursery to screen short-season soybean lines for tolerance to this disease.

Of course, knowing what disease pathogens are present in a field is the starting point for any management plan, so growers will be pleased to learn that this project also involves expanding molecular diagnostics for fast and specific identification of pathogens, which, in turn,
reduces turn-around time for final test results, and improves decision making for disease risk management.

“We would like, with this research, to be able to say we have good disease risk assessment tools so growers can select the right ones to manage soybean diseases,” says McLaren.

Supporting the Work

Of course, all the work being done on short-season soybeans requires, short-season soybean material to work with. Dr. Leonid Savitch, Research Scientist with AAFC in Ottawa, is doing some of this foundational work and providing material that Bueckert and Knight can use in their studies.

Savitch is looking to identify soybean germplasm with better cold stress tolerance and a greater ability to withstand reproductive development delays, caused by low temperatures. He is also developing screening tests to help identify these qualities more efficiently.

Essentially, Savitch is looking for soybean material that should do well in the west and Bueckert and Knight are putting it in the field to see how it performs as they conduct their own nitrogen fixation, and stress tolerance research projects.

In the end, short-season soybeans are still a very new crop. Knight says it can be hard to identify what is and is not a short-season variety because success one year may not be repeated the next. “When I look at the data, so much depends what year it is grown in.”

That is a sentiment many western soybean growers can probably relate to as they have watched a variety they have had previous success with completely collapse before their eyes for no discernable reason.

The research all these scientists are doing should provide some answers and strengthen the western soybean scene. “My client is the grower,” says McLaren. “It means a lot to me to get this information out to them. It is a good feeling.”

The CFCRA is a national collaboration comprised of provincial producer organizations and industry partners, including: Atlantic Grains Council; Producteurs de grains du Quebec; Grain Farmers of Ontario; Manitoba Corn Growers Association; Manitoba Pulse & Soybean Growers; Saskatchewan Pulse Growers; Prairie Oat Growers Association; SeCan; and FP Genetics.