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3 open minutes with Charles Brummer

Published on 30 March 2017

Dr. Charles Brummer’s research at the University of California – Davis has focused on alfalfa breeding. One area of focus is looking into the genetic basis of fall dormancy using various genetic mapping methods. His group is also evaluating a large amount of germplasm to find adapted, high-yielding, non-dormant germplasm under saline conditions and under deficit irrigation.

Progressive Forage Editor Lynn Jaynes recently talked with Dr. Brummer about his current research.

Charles Brummer is a plant breeder with the University of California – Davis

What are the issues with the current alfalfa dormancy ratings, and how is that being addressed?

Brummer: Alfalfa dormancy is assessed using a standard test that measures the height of alfalfa regrowth about three weeks following a late-season harvest. The heights are converted to a fall dormancy scale that ranges from 1 for very dormant cultivars, to 11 for very non-dormant cultivars.

A set of 11 cultivars whose dormancy responses range across the entire 1-to-11 spectrum and that have proven to be very consistent across years and growing environments throughout the U.S. are included as controls. New cultivars are assigned a dormancy rating based on their response relative to the controls.

This standard test has several issues. First, the trial is conducted by growing 100 uniformly spaced plants from each cultivar to be tested, as well as the control set of 11 cultivars, in a nursery. This trial is an addition to solid-seeded plot trials that must be grown by breeders to assess yield, persistence and other traits.

Therefore, it is added cost and time, which could be avoided if the dormancy rating could simply be determined using existing plot trials. We grew trials across California, in Wisconsin and in New York, and found that the same ratings can be obtained under either trial type. We are planning to discuss the results with the alfalfa research community and prepare an addition to the standard test.

A second question relates to the need to include all 11 controls in a given trial. Using fewer controls would reduce cost as well. We have assessed a large dataset generated at the University of California – Davis by the late Dr. Larry Teuber, and my program.

Our preliminary look at the results suggests that we may be able to reduce the controls and still maintain the same robust rating. These results need to be confirmed. The goal of these and some related research is to refine the standard test to make it as simple for breeders or evaluators to perform as possible while retaining the robust rating that has proven useful to growers and to seed marketers.

Soil salinity is an increasing concern to alfalfa growers. Where is research heading in that regard?

Brummer: Salinity is likely to become an ever more serious concern for growers of irrigated alfalfa.

“Salinity” is not one thing but actually includes several variable aspects, such as the salt composition at a given location; whether the source of salinity is the soil itself, the irrigation water or a combination of both, which affects whether salinity affects a crop immediately upon sowing or only later when irrigation begins; and non-salt-related problems of saline soils, such as decreased water infiltration, which may impose drought stress on plants more than salt stress. So taken together, salinity tolerance is a challenging trait to address.

In terms of genetic improvement, most of the seed companies as well as our program are evaluating breeding germplasm under saline conditions to identify plants that will produce cultivars with high yield under salinity stress.

Variations on the screening include germination in saline solution to assess seedling salinity stress tolerance and planting seedlings into saline fields that are then irrigated with saline water to assess the tolerance of seedlings and adult plants.

Trials may run for several years in the field before selections can be made. Most breeders want to replicate conditions plants will potentially face in growers’ fields to enable selection of plants optimally suited to those conditions. Additional research in several USDA-ARS labs is beginning to understand the genetic basis of salinity tolerance, which will hopefully accelerate progress on this trait.

As weather patterns change, how is alfalfa research addressing this?

Brummer: To me, one of the interesting breeding challenges is trying to define what the likely irrigation system will be 10 or 20 years down the road. The breeding materials we screen in the field today will be the cultivars of tomorrow. If the industry moves from flood irrigation to subsurface drip, for example, the microclimate the alfalfa plants are growing in will be quite different, and the stresses and needs of cultivars growing in the new environment could be prioritized differently than they currently are.

Further, if deficit irrigation becomes the norm in some regions of the state or country, then does a different germplasm base, maybe with different fall dormancy, become better suited to optimally use the available water?

As is often the case, alfalfa breeders need to be in tune with developments in alfalfa management as the climate changes. Breeding for an environment that no longer exists won’t result in cultivars needed in the future, but breeding for a promising management system that realistically will not be economical to use is not a wise move either.

This seems to me to be one of the more interesting times to be an alfalfa breeder in the West, given the dynamics associated with irrigation amounts, timings and consequences (such as increased salinity from drip systems).

Organic alfalfa production is a growing industry; is this sector large enough to merit specialized research, and if so, where is that research headed?

Brummer: The increase in organic alfalfa production mirrors the large increases in organic milk and meat over the past decade and more. The trend appears likely to continue and, therefore, alfalfa research on organic systems will be needed.

Organic producers face some unique challenges that conventional alfalfa growers don’t, including weed management options, particularly at establishment; insect control, especially alfalfa weevil, aphids, lygus and others; the potentially increased use of both grazing and mixtures with grasses; and the incorporation of sufficient fertility, especially in hay operations that remove considerable phosphorus and potassium with harvest.

In all these cases, research could help to optimize management and develop cultivars that would be optimally suited to the environment.

I have recently organized a team, including scientists and extension personnel from California, Montana, Wisconsin and New York, to work on both organic forage and seed production.

Currently, organic alfalfa seed production is probably more difficult than forage production due to the devastating effects of insects, especially lygus, on seed yield.

Proper management and control strategies that fit organic farming guidelines need to be identified so that more organic seed can be produced to fill this growing market segment.  end mark

Lynn Jaynes
  • Lynn Jaynes

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