Elizabeth LeeDept. of Plant Ag.University of Guelph@Maize_Canada

Ghosts of cornfields past, present and future…..

• May 23rd 2015 frost event• Weather variability• Goss’s Wilt • Genetic improvement

Things that have been on twitter….

May 23rd 2015 frost event…...

-6

-4

-2

0

2

4

6

8

10

12

14

16

18

20

22

14

:39

15

:09

15

:39

16

:09

16

:39

17

:09

17

:39

18

:09

18

:39

19

:09

19

:39

20

:09

20

:39

21

:09

21

:39

22

:09

22

:39

23

:09

23

:39

00

:09

00

:39

01

:09

01

:39

02

:09

02

:39

03

:09

03

:39

04

:09

04

:39

05

:09

05

:39

06

:09

06

:39

07

:09

07

:39

08

:09

08

:39

09

:09

09

:39

10

:09

10

:39

11

:09

11

:39

12

:09

12

:39

13

:09

13

:39

14

:09

14

:39

15

:09

15

:39

16

:09

16

:39

17

:09

22-May-2015 23-May-2015

Air

Tem

per

ature

(°C

)

• 6 ½ hours below freezing reaching a low of nearly -4°C• Plants were at the 4-5 leaftip stage (i.e., growing point is still below

ground).

Expectations: Replanting when 100% of the plants showed damaged (at 3-4 LT) resulted in about 20% increase in yield (Nebraska, Elmore & Doupnik, 1995).

6569 54 54 6257

100

200

300

400

500

600

700

UFU FFF XFX UUU FUF XUX

g

Total dry matter per plant

50

100

150

200

250

UFU FFF XFX UUU FUF XUX

g

Grain yield per plant

-0.5

0

0.5

1

1.5

2

UFU FFF XFX UUU FUF XUX

num

ber

Tiller number per plant

a a a

a

b

b

0.5

1

1.5

2

2.5

UFU FFF XFX UUU FUF XUX

num

ber

Total ear number per plant

a aa

ab

bc

c

b

aa a

aa

a

bcc

b

bcc

~4x decrease in grain yield between the XUX and UFU treatments….

0

5

10

15

20

25

30

35

40

45

-10

-5

0

5

10

15

20

25

30

35

May

11

May

12

May

13

May

14

May

15

May

16

May

17

May

18

May

19

May

20

May

21

May

22

May

23

May

24

May

25

May

26

May

27

May

28

May

29

May

30

May

31

Jun1

Jun2

Jun3

Jun4

Jun5

Jun6

Jun7

Jun8

Jun9

Jun1

0

Jun1

1

Jun1

2

Jun1

3

Jun1

4

Jun1

5

Jun1

6

Jun1

7

Jun1

8

Jun1

9

Jun2

0

Jun2

1

Jun2

2

Jun2

3

Rai

nfa

ll (

mm

)

Tem

per

ature

(°C

)

Daily rainfall Daily maximum temperature Daily minimum temperature

Context….

Moisture stress makes it worse (Carter, 1995).

May 23rd 2015 frost event Past Ghost

Did not behave as other frost events – far greater yield loss. Not sure why…. It may have had something to do with prior exposure to a below 0°C event. It may have had something to do with soil moisture status.

Would suggest that when assessing impact of early season frost damage, need info on moisture status, occurrence of previous 0°C events, duration of event.

And then just assume that at best the frost damaged plants in the stand (assuming that they survive) will yield 1.5 to 4 fold less than the undamaged plants.

Frost damaged plants lost their ability to be competitive and to exploit available resources.

Weather – your iPhone has an app for this….. It is the conditions of the atmosphere at a particular place and time.

Climate – your iPhone does not have an app for this…. It is long-term averages and trends of the atmosphere of a region.

Solar dimming = less total radiation and more of it in the form of diffuse radiation.

Solar brightening = more total radiation and less of it in the form of diffuse radiation.

Total radiation = direct + diffuse

More pollution leads to less direct and more diffuse solar radiation.

10

30

50

70

90

110

130

150

170

190

1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 2040

Gra

in y

ield

(b

u/a

c)

Production Year

US Ontario

Data from USDA and OMAFRA

Since the 1940s, this is over a 7-fold increase in grain yield….

Long-term TREND

10

30

50

70

90

110

130

150

170

190

1980 1985 1990 1995 2000 2005 2010 2015 2020

Gra

in Y

ield

(b

u/a

c)

Production Year

US Ontario

Data from USDA and OMAFRA

Phenotype = Environment + Genetics + Management + ExM + GxM + GxE + GxExM + error

Tollenaar et al. 2017 Nature Climate Change 7:275-8

Accumulated solar brightening during the grain-filling phase of maize across ten US Corn Belt states between 1984 and 2013.

Increase in county yields between to 1984 and 2013 that is attributable to solar brightening across ten US Corn Belt states (counties with >10,000 A of harvested grain corn).

Tollenaar et al. 2017 Nature Climate Change 7:275-8

Assuming that 27% of the yield increase in 2013 was due to solar brightening.

80

90

100

110

120

130

140

150

160

170

180

1980 1985 1990 1995 2000 2005 2010 2015 2020

Gra

in Y

ield

(b

u/a

c)

Production Year

Ontario Corn Yields

This is where would have been w/o solar brightening…..

This is where we are…..

Ontario Hybrid Corn Performance Trial Average Yields Across

Three CHU Zones and Provincial Average Corn Yield

1987 - 2005

80

100

120

140

160

180

200

220

240

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006

Year

Av

era

ge

Yie

ld (

bu

/ac

re)

2400 - 2700 CHU 2700 - 3100 CHU 3100 - 3500 CHU Provincial Average

2.3 bu/ac/year

2.5 bu/ac/year

2.8 bu/ac/year1.5 bu/ac/year

Hybrid "NK 3030Bt" Compared with Performance Trial Mean

Yields (bu/acre) (1997-2005)

100

120

140

160

180

200

220

1996 1998 2000 2002 2004 2006

Year

Yie

ld (

bu

/ac

re)

Hybrid Yield Performance Trial Mean

#1 Variability is caused by differences between years – variable weather.#2 Ontario is highly variable and represents an environment that occurs in small pockets.

Loffler et al. 2005. Crop Science. 45:1708-16.

Classification of environments using crop simulation from 1952 – 2002.

5 abiotic environment classes

Resilience – borrowed from ecology, and we use it in the context of a plant’s or genotype’s ability to deal with environmental variation. It is replacing the term stability…

Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-01450-2

Genomes to Fields Project

Genomes2fields.org

Days to silking

Kendall's tau B correlations

accCHU_S accGDD_S accDLI_S accRAIN_S DTA

2014 DTS 0.60** 0.46** 0.81** 0.22** 0.89**

DTA 0.53** 0.42** 0.73** 0.25**

2015 DTS 0.47** 0.30** 0.53** 0.27** 0.92**

DTA 0.47** 0.24** 0.50** 0.38**

combined DTS 0.53** 0.36** 0.32** 0.26** 0.91**

DTA 0.49** 0.30** 0.29** 0.31**

30% more light from planting to silking in 2014….

Genomes to Fields 2014 & 2015 data

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-3 -2 -1 0 1 2 3 4 5

PC

2 (

25

% o

f th

e v

aria

tio

n)

PC1 ( 59% of the variation)

KS1

MO1MO2

IA1

NY2

GA1

OH1

DE1

MO1

MO2 IA1

GA1

IL1

TX1

Relationship between days to silking and the weather data from planting to silking

2015 2014

MN1

IN1

ON1

ON2

ON2

IN1

Weather Variability…

Present & Future

Ontario is a very unique environment... There is no such thing as normal. Histroically we have been dealing with greater environmental variability than most production environments in the US.

What does this mean? (1) some managment approaches being used in the US may not be all the aplicable up here. (2) all signs are pointing to greater climate related variation, so odds are our year-to-year variation will become greater. (3) we are still learning about how envrionment impacts traits.

How can we manage the risk associated with this? Need to build in resilience. (1) invest in soil health. (2) invest in diversity. (3) do not rely completely on genetics.

Long-term trends suggest there is going to be more variation coming.

Goss’s wilt is a bacterial disease, it is not present in Ontario yet.

www.Pioneer.com

When it hits the plants early in development it causes vascular wilting.

When it hits the plants later in development it causes a leaf blight.

www.Pioneer.com

There is reason to be optimistic….

4 isolates from Manitoba

There is resistance in the short-season germplasm pool….

10

30

50

70

90

110

130

150

170

190

1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 2040

Gra

in y

ield

(b

u/a

c)

Production Year

US Ontario

Data from USDA and OMAFRA

After essentially almost 80 years on this yield trajectory, we have probably developed an unhealthy and unrealistic expectation that it will continue….

Genetic improvement….

Source – USDA-NASS

Maize = 117 kg ha-1 yr-1

Soybean = 22.9 kg ha-1 yr-1

Wheat = 31.5 kg ha-1 yr-1

Heritable differences are due to additive genetic variation (predictable) & non-additive genetic variation (unpredictable).

Genetic improvement takes 3 things:

#1 Genetic Variation – heritable differences

Selection only works on the predictable stuff…..

Therefore, we need to maintain adequate levels of additive genetic variation for our traits of interest in the direction of interest in the germplasm pool.

#2 Selection accuracy – how confident are you that it is a duck?

#3 Selection intensity – how many haystacks can you look in and how many needles should you look for?

Time – the longer it takes, the slower it is to bring a new product to market.

#1 Genetic Variation – heritable differences

GMOs – introducing a novel gene into the plant’s genome

Gene or Genome editing –altering the DNA sequence of a gene that is already present in the plant’s genome. CRISPR/Cas9

What about GMOs and gene editing to introduce genetic variation?

We’ve done the “easy stuff”…. Bt, herbicide tolerance, virus resistance, even golden rice. We understood the biology & the genetics of the traits. It was relatively affordable R&D for the companies. And there was a clear benefit to producers and they were willing to pay the additional cost.

Have to remember that corn is a commodity crop, by definition we want a lot of it and we want it cheaply. I am going to argue that the additional traits (GMO or GE) that we will see in corn will be few and far between…..