Advantages, Disadvantages, and Applications of Augmented Block Designs in Agriculture, Schemes and Mind Maps of Design

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Introduction to

Augmented Designs

Applications in Plant Breeding

Jennifer Kling

Oregon State University

Outline – Augmented Designs

 Essential features

• When are they used in plant breeding?

 Design options

• Today - one-way control of heterogeneity

 Augmented Block Design - Example

• Randomization and Field Plan
• Analysis with SAS
• Interpretation of Results

 Overview of variations on the basic design

 Software and Further References

When are they used in plant breeding?

 Early generations

• Seed is limited
• Land and other resources are limited  Want to evaluate as many genotypes as possible  Can re-evaluate selections in subsequent seasons
• Difficult to maintain homogeneous blocks when comparing so many genotypes  Need a mechanism to adjust for field variation

When are they used in plant breeding?

 Adaptation to diverse environments is a primary goal

• Participatory Plant Breeding  Farmers may prefer to grow a single replication when there are many genotypes to evaluate  May not be able to accommodate all entries
• Farming Systems Research  Want to evaluate promising genotypes in as many environments as possible

Augmented Designs - Advantages

 Unreplicated designs can make good use of

scarce resources

• Evaluate more genotypes
• Test in more environments

 Fewer check plots are required than for

designs with systematic repetition of a single

check

Augmented Designs - Advantages

 Provide an estimate of standard error that can

be used for comparisons

• Among the new genotypes
• Between new genotypes and check varieties

 Observations on new genotypes can be

adjusted for field heterogeneity (blocking)

 Flexible – blocks can be of unequal size

Design Options

 Choose a design that is appropriate for

controlling the heterogeneity in the

experimental area

• One-way blocking  Randomized Complete Block Design  Incomplete Block Designs (e.g. Lattice Design)
• Two-way blocking  Latin Square (Complete Blocks)  Youden Square (Incomplete Blocks)  Row-Column Designs

Design Options

 Underlying design refers to assignment of

checks to the experimental units

 All augmented designs are incomplete with

respect to the new entries

 Can be replicated in different environments

• Need to consider relative efficiency compared to other possible designs

Meadowfoam ( Limnanthes alba )

 Native plant first produced as a crop in 1980

 Seed oil with novel long-chain fatty acids

• light-colored and odor free
• exceptional oxidative stability

 Used in personal care products

 Potential uses

• fuel additive
• vehicle lubricants
• pharmaceutical products

Meadowfoam in Oregon

 Good rotation crop in the

Willamette Valley

• Winter annual
• Plant and seed meal are high in glucosinolates
• Same equipment as grass seed

The Germplasm

 Diverse breeding populations were inherited from a retired breeder (Gary Jolliff)

 Populations were regenerated in the greenhouse and selfed

 S 2 lines were transplanted to the field and allowed to outcross

 Insufficient seed for replicated progeny trials

 Goal - form a broadbased pool for recurrent selection

• Screen S 2 -testcrosses
• Recombine selected S 2 parents

The Experiment (2007-2008)

 New treatments:

• 50 S 2 -testcross families

 Check varieties:

• Ross (C1)  Cycle 4 of an elite population (OMF58)  Widely grown commercial variety
• OMF183 (C2)  Cycle 5 from OMF
• Starlight (C3)  released variety derived from this germplasm collection

Statistical Model

Yij  μ + β + c + τi j k(i) + εij mean + blocks + checks + new entries + error

Field Plan

 Include a sufficient number of checks and replicates to provide a good estimate of experimental error and adequate power for detecting differences among varieties

 Arrange blocks along field gradient to maximize variation among blocks and minimize variation within blocks

 Assign each of the checks at random to each block

 Assign new entries at random to remaining plots

 On-line tool for randomization: http://www.iasri.res.in/design/Augmented%20Designs/home.htm