The Extension Challenge of Crop Variety Selection in Colorado

Plus LSD Alpha Level Revisited

Plus

Painting a Picture Jerry J. Johnson

Professor and Extension Specialist Colorado State University Crops Testing Program

Now, I answer them differently:

“Imagine you are a farmer and you have to

decide which variety to plant. I give farmers

unbiased and research-based data to decide.”

Upon learning I am a professor at CSU I am asked:

For years I tried to explain: “I’m in charge of Crops Testing. When there are new crop varieties I conduct field experiments to see if they are adapted to our conditions.”

They give me a blank stare and say---

“How do you stand on GMOs? You must believe in them”

Then I give them a blank stare not knowing where to start---

“What do you do?”

“What do you Teach?”

Every field which variety to plant.

Every Year, Every farmer must decide,

For the past 11,000 years: every farmer

Every year, Every farmer must decide

Every year, Every farmer, Every field

And,

every future farmer!

What is the total variety decision worth for all crops tested by Crops Testing in Colorado?

(Assume 2% genetic gain per year)

Total potential value of variety decision annually = $22,091,000

Corn $12,828,000 Wheat $6,004,000 Sorghum $2,000,000 Proso millet $460,000 Dry Beans $453,000 Sunflower $346,000

The Extension Challenge for Crop Production in Colorado

Approximate Cropland Area: 10.6 Million Acres

Number of Farms and Ranches (2017): 33,800

Why I use LSD: α = 0.30 Short answer: (Other smarter people) • Carmer, S.G. 1976. Optimal significance levels for application of least

significant difference in crop performance . Crop Sci. 16: 95-99 • Johnson, J.J. 1989. The advantages and disadvantages of replications in on-

farm sorghum variety tests in North Cameron. MS Thesis. Washington State University

• Johnson, J.J., J.R. Alldredge, S.E. Ullrich, and O. Dangi. 1992. Replacement of replications with additional locations for grain sorghum cultivar evaluation. Crop Sci. 32:43-46.

• Campbell, K.G., Y.M. Thompson, S.O. Guy, M. McIntosh, and B. Glaz. 2015. “Is, or is not, the two great ends of Fate”: Errors in Agronomic Research. Agronomy Journal 107, Issue 2:718-729.

• Bowman, D., D.Dombek, and J. Still. 2017. Journal of Crop Variety Testing. Vol. 1:1-7.

REPORTING DATA IN CROP PERFORMANCE TRIALS IN THE

UNITED STATES Daryl T. Bowman, Don Dombek, Joshua Still

How data are reported is critical in how that data are used and interpreted

This review paper looks at various aspects of data reporting using surveys and scientific articles on the subject

Surveys covered wheat (Triticum aestivum L.), corn (Zea mays L.), and soybeans (Glycine max (L.) Merr.)

We recommend reporting a minimum of mean and Least Significant Difference (LSD) choosing a significance level preferably between 0.20 and 0.40.

Table 1. Statistics reported from crop performance trials in 30 states

Published in Journal of Crop Variety Testing Volume 1:1-7 (2017)

Mean LSD. 5% LSD 10% LSD 20% LSD 25%

30 13 14 1 2

Why I use LSD: α = 0.30 • It is important for each researcher to think about the risk structure.

• Is Type I error important? • Is Type II error important?

As risk of Type I error decreases:

Risk of Type II error increases

Type I Type II

Should I plant Variety A or Variety B that are the same for all characteristics except yield?

Risk Structure for Variety Selection

Johnson says the data says: “Variety A is better than Variety B when, in reality and unbeknownst to Johnson, the two varieties are equal yielding. Whichever variety I choose, I don’t lose anything. Johnson just loses face because he committed Type I error, I suffer no economic loss. I don’t care about protecting myself against Type I error

Johnson says that the data says: “Variety A is equal yielding as Variety B when, in reality and unbeknownst to Johnson, the two varieties are not equal yielding.” Half of the time I will choose the variety that is actually lower yielding, I suffer loss half of the time Johnson doesn’t just lose face because he committed Type II error, I suffer economic loss. I care about protecting myself against Type II error

Unfortunately Type II error risk can not be set to obtain a corresponding LSD; like for Type I error, i.e. LSD 0.05

Carmer’s Argument:

The most practical way to control Type II error is to set a different level of Type I error. Thus α = 0.30 instead of α = 0.05

LSD Type I ( ) = 0.30 Every researcher must think about the risk structure.

• Is Type I error important? • Is Type II error important? • Is Type III error important?

Type I Type II Type III

Type I = .001 Type II = .999 Type III =.001

As risk of Type I error decreases

Risk of Type II error also decreases

Risk of Type II error increases

Johnson says that the data says, Variety A is superior yielding to Variety B when, in reality and unbeknownst to Johnson, Variety A is significantly lower yielding than Variety B. Johnson doesn’t just lose face because he committed Type III error, I suffer economic loss. 100% of the farmers selecting Variety A would lose yield. I care about protecting myself against Type III error

Implied Type III error comprised of two errors: ½ of Type II error and pure Type III (choosing to plant variety that is significantly lower yielding than the one that stats said was significantly higher yielding). A farmer could reasonably want to keep Type III error below 0.10

Breeders Capable of Breeding Many More Types of Wheat than Before

• 1995: CO wheat breeding program bred only Hard Red Winter Wheat Since: • Russian Wheat Aphid resistance • Hard White Winter Wheat • High-quality wheats • Clearfield wheat (Single-gene & double-gene) • Disease resistance • Wheat stem sawfly resistance • ACCase herbicide resistance

Is Variety B with some desirable trait equal yielding to Variety A (without the trait) but the same for all other characteristics except yield?

Risk Structure for Variety Selection

Protect against falsely asserting Variety B (with the trait) is equal yielding as Variety A (no trait). Is there a yield drag associated with a trait? Type I error right? Different risk structure.

The Heart of Change – J.P. Kotter & D. Cohen

“People change what they do less because they are given analysis that shifts their

thinking than because they are shown a truth that influences their feelings”

Brand-Hybrid Yield MoistureBu/Ac %

Dekalb DKS53-53 104.5** 15.3 aDyna-Gro 772B 102.8* 14.8 aTerral REV 9924 97.9* 14.9 a bTerral REV 9562 97.9* 15.1 a bDyna-Gro GX15672 96.4* 15.0 a bTerral REV 9782 96.3* 14.9 a bDyna-Gro GX15484 96.2* 14.8 a bDekalb DKS45-23 95.0* 15.1 a bAlta AG3101 94.6* 15.1 a bDyna-Gro M60GB31 94.5* 14.8 a bAlta AG1203 94.4* 14.6 a bAlta AG2103 93.0* 14.8 a bAlta AG2105 90.1* 14.9 a bAlta AG3201 88.4* 14.5 a bDekalb DKS38-16 87.2* 15.0 a bDekalb DKS48-07 83.1 15.0 bAlta AG1401 73.8 13.7Dyna-Gro GX16675 71.8 15.3Alta AG1201 57.2 14.6

MEAN 90.3 14.9LSD (10%) 18.8 0.7CV (%) 10.5 2.2

**Highest yielding variety in test*Yield not significantly less than the highest yielding variety in the test

Difference in yield? Only

significant difference

Dryland

Hard White

Premium

SnowmassYR: 6 WSMV: 3

SunshineYR: 5 WSMV: 8

No Premium

AnteroYR: 2 WSMV: 5

JoeYR: 1 WSMV: 3

Hard Red

Clearfield

Single-gene

High Yield

Oakley CLYR: 1 WSMV: 2

Double-gene

Brawl CL PlusYR: 5 WSMV: 7

Non-Clearfield

High Yield

Early Maturity

LanginYR: 3 WSMV: 6

WB-GrainfieldYR: 2 WSMV: 8

Medium Maturity

AveryYR: 6 WSMV: 3

ByrdYR: 7 WSMV: 2

LCS MintYR: 4 WSMV: 5

Medium-Late Maturity

SY MonumentYR: 2 WSMV: 8

DenaliYR: 7 WSMV: 3

YR=Stripe rust rating (1=resistant, 9=susceptible) WSMV=Wheat streak mosaic virus rating (1=resistant, 9=susceptible)