Acorn Strategies

How Acorn Size Influences Seedling Size and Possible Choices

Acorns Sized by Round Hole Screens

• Four nurseries in Study– Wilson, JP : Red oak only – Valonia, Penn : Red and white oak

• Made as many sizes as possible with round hole screens

• All lots floated to remove poor seeds• Planted by hand for precise placement• Fall 2001

Sizing red oak acorns with round hole screens

Sizing red oak acorns with round hole screens

Comparison of largest and smallest acorn

Line up of red oak acornsLargest acorn on left

Experimental seedbeds at the Penn Nursery

Hand planted acornsMeasured plot marked with pink

flagging held by a nail

2-0 white oak seedlings at the Penn Nursery

2-0 white oak, Penn NurseryLarger acorns planted on left

Smaller acorns planted on right

Data from Wilson and JP

• Red Oak only• 1-0 seedlings• Wilson 8 sizes and 10 blocks• JP 10 sizes and 8 blocks• Trees undercut with tractor, lifted by hand, bagged

by plot• Measured at Purdue• Plot means analyzed by regression

Seedling Height vs Acorn Size Wilson

20

30

40

50

60

40 44 48 52 56 60

Acorn size

HE

IGH

T

HEIGHT

Predicted HEIGHT

Seedling Diameter vs Acorn Size Wilson

4

4.5

5

5.5

6

6.5

7

40 44 48 52 56 60

Acorn Size

Se

ee

dli

ng

Dia

me

ter

DIA

Predicted DIA

Seedling Fresh Weight vs Acorn Size Wilson

15

20

25

30

35

40

45

50

40 44 48 52 56 60

Acorn size

Se

ed

lin

g F

resh

We

igh

t

FW

Predicted FW

Seedling Root Volume vs Acorn Size Wilson

10

15

20

25

30

35

40

40 44 48 52 56 60

Acorn size

Ro

ot

Vo

lum

e

RV

Predicted RV

Seedling Height vs Acorn Size JP

30

40

50

60

70

38 42 46 50 54 58

Acorn size

HE

IGH

T

HEIGHT

Predicted HEIGHT

Seedling Diameter vs Acorn Size JP

5

5.5

6

6.5

7

7.5

8

4042 4446 485052 5456 5860 6264

Acorn size

See

dlin

g D

iam

eter

DIA

Predicted DIA

Seedling Fresh Weight vs Acorn Size JP

20

30

40

50

60

70

38 42 46 50 54 58

Acorn size

Se

ed

lin

g F

resh

We

igh

t

FW

Predicted FW

Root Volume vs Acorn Size JP

10

15

20

25

30

35

40

45

38 42 46 50 54 58

Acorn size

Ro

ot

Vo

lum

e (

cc)

RV

Predicted RV

So What?

• Larger acorns on the average give bigger average seedlings.– Aid in getting bigger trees– Tailor fertilizer and water to the acorn size for

uniform crop.

• Smaller acorns can be stored “on the stump”– Large acorns 1-0– Smaller acorns 2-0

Next Step

• Size larger seed lots with mechanical sizer

• Plant larger plots

• Test how the procedure goes operationally

• Two more nurseries to lift

• Take data on white oak

• JP seedlings have been outplanted– Does this treatment effect field performance?