Skip to content

Rooting traits affecting drought tolerance

Principal Investigator

Hugh Earl

Research Institution

University of Guelph

External Funding Partners

This project was funded in part through Growing Forward 2 (GF2), a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of GF2 in Ontario.

Project Start

April 2014

Project End

October 2017


  • Develop a controlled environment culture system that permits realistic rooting depths and soil water profile gradients that mimic field conditions.
  • Determine the soil water profile conditions that result in perception of drought stress by the plant.
  • Determine if soybean varieties adapted to Ontario differ in their ability to effectively extract deep soil water during a simulated natural soil drying cycle.
  • Determine if there are variety differences in soil water extraction during water stress that result in differences in susceptibility to yield loss and, if so, determine which yield components are affected.


  • The development of a convenient method for characterizing soybean variety differences in root functional traits thought to be essential for drought tolerance could lead to drought tolerant soybean varieties.
  • The improved understanding of the physiological basis of yield reduction in soybean, as caused by transient soil water deficits with different timings and intensities will help breeders identify specific traits to be targeted for future improvement.

Scientific Summary

While increases in atmospheric CO2 concentrations are likely to have a direct positive effect on soybean productivity, other aspects of climate change (increased air temperatures; possible increased frequency of extreme climate events including drought) are expected to be detrimental to yield potential. Even in the absence of climate change effects, year-to-year fluctuations in growing season precipitation are already a major challenge. Recent Grain Farmers of Ontario-funded research has shown that even in unusually wet years, soybean yields in Ontario are reduced by transient soil water deficits, especially during the latter part of the season; in drier years yield losses can exceed 25%. In order to deal proactively with future yield limitations associated with soil water deficits, improving drought tolerance is a major focus of most soybean variety development programs. Such efforts have been hampered by a lack of knowledge about the specific plant traits that would benefit soybean under realistic water stress scenarios (i.e., the timing, intensity and duration of water stress that actually limits yields under Ontario field conditions).

In this project we will identify specific plant traits that will protect yield potential of soybean crops that encounter water stress, and screen available Ontario-adapted germplasm for variation in those traits. The phenotyping system we are developing is novel, in that it provides for realistic rooting depths in mineral soil, and emulates soil water profiles that occur in the field – characteristics that are necessary for identifying root function phenotypes, and for creating realistic field-like soil water deficit events. We will provide these phenotyping tools to soybean breeders to be used in genetic selection, gene discovery, and testing of putatively drought tolerant transgenic lines. Improvement of soybean drought tolerance will help mitigate yield losses associated with long-term climate change as well as current year-to-year variation in precipitation.