Michigan’s Thumb area educators study corn populations with differing ear types

Thumb Ag Research and Education determined that under 2012 conditions, there was not a difference in yield between corn ear types, regardless of population.

Michigan State University Extension educators in the greater Thumb area studied three corn hybrids with differing ear types, determinant versus semi-determinant versus flex, at four planting populations. These studies were established on farms in Capac and Elkton, Mich.

A determinant ear type hybrid produces a fixed ear length regardless of plant population or external stressors. A hybrid with a great deal of flex will produce a shorter ear at a greater   population, or a longer ear at lower populations. A semi-determinant hybrid will change its ear length, but to a lesser degree than a flex hybrid.

The determinant hybrid was Great Lakes 5245, the semi-determinant hybrid was Great Lakes 5306 and the flex hybrid was Great Lakes 5339. Targeted populations ranged from 32,000 seeds per acre to 41,000 seeds per acre, planted in incremental increases of 3,000 seeds per acre. The corn was planted in 30-inch rows.

The target population was what was actually planted. Stand counts were taken in August to determine actual plant population (Table 1). There was no statistical difference in any of the populations in the 2012 environment. Yields did trend higher as populations increased, and the “flex” hybrid did tend to yield a bit higher than the other two ear types (Table 1).

Table 1. Performance of three corn hybrid ear types at varying planting populations.

Ear type

Target pop

Actual pop

Yield

Yield by ear type

Flex

32,000

31,250

211.0

Flex

Semi Det

32,000

30,750

208.2

214.2

Det

32,000

30,500

211.8

Semi Det

Flex

35,000

33,750

215.1

212.7

Semi Det

35,000

35,000

209.7

Det

Det

35,000

34,250

207.3

212.0

Flex

38,000

37,000

215.4

 

Semi Det

38,000

36,000

217.4

 

Det

38,000

35,750

213.6

 

Flex

41,000

38,250

215.5

 

Semi Det

41,000

39,750

215.6

 

Det

41,000

40,000

215.4

 

C.V. (%)

 

 

7.8

 

LSD @ 0.05

 

 

19.8

 

This group of educators has looked at corn single hybrid planting populations in the past (2008-2010). Test populations ranged from 24,000 to 36,000 seeds per acre in 2,000 seed increments. In those studies, there was never a significant yield increase beyond 32,000 seeds and greater.

The educators gratefully acknowledge the support of Lynn Island Farms, The Huron Corn Growers Association, Great Lakes Hybrids and the Corn Marketing Program of Michigan.

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