Development of a protocol for testing waterlogging resistance in winter cereals

Principal Investigator: Michel McElroy and David Hooker

Research Institution: CEROM and University of Guelph

Timeline: April 2019 – December 2022   

Objectives:

• Develop a novel system for the evaluation of excess water/ice stress in fall-seeded cereals.
• Assess the feasibility of using said system as a tool for wheat breeding and cultivar evaluation.

Impacts:

• The short-term impact would be the development of an inexpensive field method that would allow agronomists and producers to test available varieties of winter wheat for their performance under spring waterlogging conditions. This would provide valuable information in cultivar selection for producers in soils with less-than-ideal drainage.
• Long-term impact would be a potential new tool for plant breeders to efficiently screen genotypes for resistance to stresses associated with excess water, potentially accelerating the development of new cultivars better adapted to the effects of climate change.

Scientific Summary:

Long-term studies have demonstrated the crucial role of winter wheat in crop rotations, but its feasibility as a crop option depends heavily on winter survival, especially in eastern and northern Ontario. Excess water during the late-winter/early-spring freeze-thaw cycle period in particular is associated with multiple abiotic stresses, including ice encasement, frost-heaving and waterlogging. As temperatures increase, standing water can also cause a proliferation of root-borne diseases causing further damage. Management practices can limit the severity of excess water, but many major factors in poor drainage (soil type, topography) are beyond the control of producers. Climate change models forecast an increase in extreme precipitation events and greater variation in winter/spring temperatures in Eastern Canada, elevating the risk of damage from excess water.  

One potential solution is the use of cultivars that are better adapted to stresses associated with water stress. Unfortunately, selecting for these traits can be difficult and cumbersome: waterlogging under natural conditions is typically patchy in distribution, resulting in an uneven stress pressure, while assays under greenhouse conditions are expensive and do not reflect the multiple stressors present under field conditions. Optimally, testing for water stress among cultivars would be analogous to disease, where plants are allowed to grow under near-natural field conditions while applying an even and measured disease pressure to ensure that plants are subjected to the same stress. This project aimed to develop a field system to properly evaluate excess water stress for winter wheat, using a hill-and-furrow system to simulate different topographies.

Results

The project developed and tested a field protocol for evaluating winter waterlogging resistance using furrows/ridges. By seeding small plots of winter wheat within furrows, we hoped to replicate the effects of spring water engorgement and develop a standard protocol for evaluating this stress. The study was broken down into two phases. The first one tested a number of experimental factors (ridge height, winter covering and spring irrigation) with a small number of cultivars (three) with the objective of determining which treatments would be critical (and feasible) to test for survival. The second phase took the best set of treatments from phase one and applied them to a greater number of cultivars (ten) to determine if the protocol was sensitive enough to detect varietal differences in tolerance. The experiment was repeated at two sites: Beloeil in Quebec and Ridgetown in Ontario.

The first phase identified treatments that were more practical on a field execution level: e.g., a ridge depth at 15 cm retained spring snow melt as intended while not causing problems for on-ridge seeding, in contrast to irrigation treatments that early in the season were deemed too difficult and potentially damaging to equipment. The second phase, in which varieties were assessed, did not produce any significant differences, or indeed much difference in winter survival between ridge/furrow treatments.

With the final data collected and analyzed, it seems clear that the proposed methodology cannot effectively evaluate winter survival/waterlogging tolerance as intended. While the techniques assessed in this study did in some cases produce interesting results, it is fair to say that as a tool for assessing varietal resistance to waterlogging/ice encasement, they are not effective. Survival across years tended to follow the general trends observed in adjacent fields, indicating that the placement in furrows offered no significant additional stress. When the effects of stress were observed, they were not in patterns consistent enough to be able to evaluate varieties. As such, no factsheet / protocol for the technique was produced or disseminated.

While it is disappointing that we were not able to develop a protocol that could be used to screen for a stress that is important to eastern Canadian winter wheat producers, the study did underline the complexity of waterlogging / ice encasement damage and help direct future research in this area. Results suggest that specialized field trials may be unsuitable for assessing a stress that is largely dependent on weather, without taking steps to produce large-scale flooding/freezing artificially. Conversely, it may be more practicable to develop growth-chamber protocols that mimic field conditions during these events. In the latter case, a more thorough study of the conditions under spring ice (temperature, oxygen levels, physical compression from soil engorgement and freezing) may allow for the design of a practical, low-cost assay for breeders and agronomists. Further studies will concentrate on modifying and/or refining protocols in a more controlled environment.

External Funding Partners:

Producters de Semences du Quebec

Project Related Publications

None.