Plant Growth Chambers for Soybean Research

Sep 22, 2026

Soybeans (Glycine max)

Soybeans belong to the Fabaceae or Leguminosae family commonly known as the legume, pea or bean family. Fabaceae is the modern standardized name based on the type genus Faba whereas Leguminosae is the older, traditional descriptive name based on the characteristic fruit. Both are used to describe the legume family.

Soybeans were domesticated 6,000-9,000 years ago from the wild which resulted in improved agronomic traits and yields. In recent times, soybeans have experienced remarkable global growth. In 2023, worldwide soybean production reached 371 million tonnes, making it the second most-produced oil crop globally after oil palm fruit.

Since 2010, soybean production has increased by 40%, reflecting its growing importance in global agriculture.¹ Today, yield predictions indicate that at the current rate, yields will only increase by half of what the demand will be in 2050². Rather than land area expansions, breeding for climate-resilience under increasing climate extremes is critical to meet future soybean demand.

Soybeans growing in a Conviron chamber at the University of Minnesota, where researchers study plant growth and environmental interactions.

Soybeans are short-day annuals that can have determinate, semi-determinate and indeterminate growth habits. They, like other legumes, have the ability to fix atmospheric nitrogen known as biological nitrogen fixation when the roots partner with rhizobial bacteria. Under the right conditions, up to 90% of the nitrogen used by soybeans can be provided through biological nitrogen fixation.

Soybeans are valued for their high protein and oil contents with the end uses of 72% for animal feed, 18% for oils (food and biodiesel), 7% whole been use (tofu, soy milk) and 3% other. The top global soybean producer is Brazil, followed by the United States, Argentina and China.³

Some Climactic Factors Affecting Soybeans

Although sometimes studied independently, climactic factors have complex synergistic or antagonistic effects. Resilience to climate variability is often studied under controlled multi-factorial stress combinations:

1) CO2, Temperature and Drought: Controlled experiments and predictive modeling found a ‘Triple Effect’ between CO2, temperature and drought. Elevated CO2 offsets some of the stresses and yield reductions imposed by high temperatures and drought⁴.

2) Night temperatures are rising faster than daytime temperatures. Every 1°C increase in night temperature above 23°C resulted in a 2.8% decrease in soybean grain yield. Soybean physiology is more sensitive to high night temperatures in the reproductive vs vegetative stages⁵.

3) For many field crops, waterlogging is considered to be the second most serious hazard after drought. Waterlogging is becoming a greater problem due to increased excessive rain events. Soil saturation decreases the amount of available oxygen leading to hypoxia which results in yield losses, decreased respiration and reduced nodulation. However, hypoxia is typically reversible once excess water has drained away, although the extent of waterlogging tolerance and subsequent recovery varies among cultivars⁶.

Soybean Speed Breeding in Growth Chambers

Breeding for climate variability resilience and recovery from stress is needed to meet the increasing global demand for food and materials from soybeans.

Over the last 40 years many soybean speed breeding protocols have been published that included the use of growth regulators, low temperatures, CO2 enrichment, far-red light and more recently LED spectral distributions. All of these contributed to decreasing the generation time from 1-3 generations per year in the field or greenhouse to 4-5 generations per year. One problem with soybean generation cycles is they are short-day plants and are typically grown under short days for their entire life cycle to induce flowering. This limits growth as the daily light integral under constant irradiances is lower. Increasing the day length after flower initiation helped overcome light limitations for increased speed while an improved seed germination technique has further reduced the generation time enabling 6 generations per year⁷.

Table 1. Above, speed breeding protocol environmental set points and green seed harvest time for the optimized growth and germination protocol.

Figure 1. Below, visual seed to seed soybean speed breeding protocol adapted from Aciksoz, S.B. et. al. A: Green seeds were harvested, dried, sanitized, germinated with GA and transplanted. B. Soybean generational time. Photoperiod was extended to 22 h from anthesis until harvest. NOTE: Layout and visual presentation below have been modified while preserving the original information.⁷