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“To Be or Not to Be…” Considerations at the Intersection of Breeding Apples and Climate Change

Posted by Sonia A. Hall | March 29, 2022

Q&A with Apple Breeder Dr. Kate Evans

Dr. Kate Evans
Dr. Kate Evans, WSU.

I recently had some highly educational and thought-provoking conversations with Kate Evans, Professor of the Department of Horticulture and director of the Pome (apple and pear) Fruit Breeding Program at Washington State University. These conversations broadened my thinking on plant breeding and climate change from a focus on understanding to what extent plant breeders might be considering climate change in their breeding programs, to all the complexity of what plant breeding is about, how it fits into a much broader context of production and management practices that can help growers adapt to a changing climate, and the range of challenges and opportunities that face a crop—in this case apples—and its associated industry as we experience and prepare for the changes our climate will bring. Here’s what Dr. Evans had to say.

Sonia A. Hall (SAH): Please describe the focus of your breeding program.

Dr. Kate Evans (KE): In thinking about your questions, I have focused on apple scion breeding rather than the wider scope of pome fruit in general. My aim is to produce a portfolio of new, improved, unique apple varieties that are selected for the environment of central Washington and available to Washington’s growers.

Two photos with trays of five apples each, placed with different orientation, and a size bar for reference.
Standard illumination photos help evaluate the appearance of apple varieties under selection. Photos: Kate Evans.

SAH: How, if at all, do you currently integrate climate change considerations into your breeding program?

KE: Perhaps not specifically addressing climate change, however my advanced selection trial plantings are purposely spread throughout the state to enable more robust selection. Our northernmost planting is a high elevation late season site. Our southernmost planting is a hot early season site.

SAH: What traits or characteristics do you focus on in your current breeding program? How might those traits or characteristics confer the ability to adapt to future climates, that could be warmer in all seasons, with increasing variability and extremes?

KE: The principal traits of focus are all linked to consumer acceptance – eating quality, appearance, and consistent quality after long-term storage. There is a small focus on resistance to disease, fire blight and powdery mildew. We may of course see an increase in prevalence of these diseases in a future climate.

SAH: What trade-offs do you consider, or would you need to consider, in breeding for warmer conditions, longer frost-free periods, and likely wetter springs and winters, drier summers, and a shift in the availability of irrigation water to earlier in the year (as expected in much of the Pacific Northwest)?

KE: Warmer conditions will lead to more sunburn, so we need to understand more about the genetically controlled aspects of the fruit surface that enable different seedlings to respond differently to high temperatures. Wetter springs could increase the prevalence of certain diseases in apple. Luckily most other production areas of the world have wetter springs than central Washington, so there is germplasm available with differing levels of resistance to disease, some of which are already in my breeding parent pool. Predicted climate change here shows we are likely to retain sufficient winter chill for fruit bud formation. A bigger potential problem would be more frequent erratic temperature changes which damage trees and buds. Addressing irrigation water availability is more about rootstock choice and tree management than about scion traits. However, there are most likely genetically-controlled differences in water-use-efficiency that could be selected for.

Two photos showing clusters of apples on the tree, with different degrees of browning due to sunburn.
Warmer conditions lead to more sunburn, making it important to understand the genetically controlled aspects that enable seedlings to respond differently to high temperatures. Photos: Kate Evans.

SAH: Are there resources—online tools, Extension or other publications, events, etc.—that you know of that can help agricultural professionals integrate climate change into their work assisting producers with variety choice?

KE: Not that I am aware of, however this is an area of a recently proposed collaborative project. Should funding be available, some of these resources could be developed over the next few years.

There I was, thinking I was asking straightforward questions and instead finding a wealth of complexity that needs to be considered. One key lesson I took away is that programs like Dr. Evans’, that were designed to serve growers across a broad range of growing conditions and focused on a crop that is grown under very different conditions around the world, have tools that can give them a step up in terms of understanding how their varieties may perform under future climates. I also walked away with a strengthened sense of the importance of having these conversations, so climate change and adaptation research can continue to come together with plant physiology, genetics, plant pathology and other such research to address the gaps in resources that can help those most likely to feel the impacts of climate change prepare and adapt to the changes to come.

This article is also posted on AgClimate.net, and is part of their plant breeding and climate change series, that shares insights from public plant breeders around the Pacific Northwest on their breeding programs and how climate change considerations intersect with their work.

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