Marketing niche hybrids - Amylomaize (high amylose), waxy, high-protein (lysine), high-oil, White and yellow food, high available phosphorus, silage, sweetcorn, and popcorn
Management tool hybrids - imidazolinone (IT/IR), Bt-CB, Bt-CR, glyphosate resistant (RR), glufosinate resistant(LL), sethoxydim resistant (SR), "stacks"

DENT

2/3 of starch is hard and 1/3 is soft
Dent caused by shrinkage of soft starch in crown as kernel dries. Surrounding hard starch shrinks less
95%+ of US corn is dent corn

SWEET CORN

Endosperm contains water soluble reducing sugar instead of starch
Plants are leafy and tend to tiller
Leading states are WI, MN, and IL

FLINT

Very hard kernels, entire crown is hard starch
Grown where season is too short for dents
Kernels resist insect damage, but may be difficult for animals to digest

FLOUR

Starch is soft and easily ground into meal
Surrounded by thin layer of hard starch
Widely grown by American Indians

POP

Closely related to flint, but higher % of hard starch in pop corn
Moisture in each starch grain expands with heating
Good popper expands to 24X or more of its original volume
Popcorn Institute; 401 N. Michigan; Chicago, IL 60611-4267 (312) 644-6610

POD

Each kernel is surrounded by husks
No economic importance

HIGH-OIL

Larger germ than normal corn
2x more oil content

WAXY

Special kind of starch with a waxy (shiny) appearance
Normal corn starch: 72% amylopectin (branched chain), 28% amylose (straight chain)
Waxy starch: 100% amylopectin
Introduced from China more than 90 yrs ago by an observant Presbyterian minister in Shanghai who noted its unusual endosperm
Endosperm stains light red (Normal endosperm = dark blue)
Slight improvement over dents in feeding value for fattening cattle
Increased in popularity in US after SCLB epidemic in 1970
No difference between dent and waxy corn in yield
Used in food products (pie thickener and tapioca pudding) and industrially (glue for stamps and envelopes)

Selection Criteria

Important traits and characteristics that a variety or hybrid must have before it can be grown on-farm.

Example: For corn use a Performance Index = PI

Yield potential: PI = 50 %
Maturity (moisture): PI = 35 %
Standability: PI = 15 %
Quality
Other factors

Criteria for Grain Hybrids	Criteria for Silage Hybrids
Grain yield	Forage yield
Grain moisture	Forage quality (i.e. Starch content, NDFD, and NDF)
Plant lodging	Disease and Insect resistance
Disease and Insect resistance	Plant lodging
Grain quality (i.e. Test weight, kernel breakage susceptibility)	Forage moisture
Other factors	Other factors

Yield potential and performance consistency

PI = 50 %

Information sources
Top performances - What is your yield potential?
Importance of using multi-location averages and PI

Maturity (moisture)

PI = 35 %

Full season hybrid or variety: A hybrid or variety that uses (or requires) the entire available growing season to reach physiological maturity before killing frost or cool temperatures end the growing season.

Often has better yield potential than a shorter-season hybrid.

Full-season maturity depends upon:

Growing season temperature GDD
Soil type / texture / topography
Tillage system
Previous crop
Planting date

Percentage of farm in various maturities depends upon:

When you start planting
How fast you plant
Acres to plant
Days available / needed for spring fieldwork before planting
Drying costs
How fast you harvest, haul and dry
Days available / needed for fall fieldwork after harvest
Corn silage / high moisture grain acres
Your desire to take risks. Example: Suggested maturity ratios - conservative vs. risky
- 50 % full-season (plant first)
- 30 % mid-season
- 20 % short-season

Relative maturity switch dates

Plant Full-season hybrids until May 10
Plant Mid-season hybrids from May 10 to May 25
Plant Short-season hybrids after May 25 to June 10
Switch to another crop after June 10

Standability

PI = 15 %

High amounts of lodging will slow harvest and decrease yields.

Caused by:

Disease
Insects
High winds

Hybrid's ability to develop a root system

Pest resistance

No hybrid or variety is resistant to all pests

Check with seed dealer about: stalk rot, rust, northern leaf spot, smut, Gibberella ear rot

Ear and Kernel Qualities

Quality factors

Test weight, protein, etc.

Other factors

Type of cross: greater yield potential with single crosses
Seed size and quality
Hybrid response to management - i.e. soil type, plant population, conservation tillage, soil fertility, herbicides, crop rotation, and irrigation
Specialty uses
"Yield lag" v. "yield drag"

Selecting the Top Performers

What data should you use?

Information sources
- Seed company
- Unbiased (university) performance trials
- Local on-farm trials using field-scale equipment
Top performances - What is your yield potential?
Strategies for selecting hybrids in the UW trials
Importance of using multi-location averages and PI

Conclusion: Use multi-location, average data (wide range of locations and climates) for selecting the top performers

Steps in the hybrid selection process:

Begin with trials in zones nearest your farm
Compare hybrids with similar maturities within a trial
Evaluate consistency of performance across zones & years
Compare performance in other unbiased trials
Consider hybrid performance for other traits, i.e. standability, dry-down rate, grain quality, etc.
You are taking a tremendous gamble if basing your decision on one or two local test plots.

Summary

Multi-Location information should be used to evaluate:

Grain yield
Moisture and maturity
Standability

Single-Location information should be used to evaluate:

Consistency of performance
Test weight
Dry-down rate
Grain quality
Ease of combine-shelling or picking

The Wisconsin Corn Evaluation Program

The University of Wisconsin Corn Hybrid Trials -- Selecting the Top Performers

The Wisconsin Grain Relative Maturity (GRM) System for Corn

Corn Silage

Background

Importance of Corn Silage to Wisconsin
- Largest acreage and production among U.S. States
- Used extensively in forage base for state dairy herds
Changing Wisconsin dairy production ‘climate'
Wisconsin Corn Silage Consortium (Coors et al.)
- Range for NDF and digestibility among commercial hybrids sold in Wisconsin is narrow.
- Yield and quality differences among corn hybrids are repeatable.
- Corn silage quality can be predicted using NIR

Corn Silage Compared to Other Forages

Advantages

Palatable forage
High dry matter yield and energy content
Consistent quality
Less labor and machinery (one harvest). Lower cost per ton of dry matter
Manure management
Flexibility, dual purpose

Disadvantages

Few established markets
Relatively low in protein
High transportation costs
Must be fed on or near farm
Expensive storage facilities
Limited production on erodible soils due to conservation requirements

What makes a good forage? (Carter et al., 1991)

High yield
High energy (high digestibility)
High intake potential (low fiber)
High protein
Proper moisture at harvest for storage
Ultimate test is animal performance
- Milk2000 is our best predictor for performance (Schwab - Shaver equation)

Hybrid Selection

Criteria for Selecting Silage Hybrids

Grain yield: allows flexibility (dual purpose)
Whole plant silage yield
Relative maturity: 5-10 days later than grain hybrids
Standability: allows flexibility
Pest resistance
Silage quality

"Variation for silage yield and quality exists among commercial hybrids in Wisconsin."

"Dual Purpose" Hybrids versus Silage Specific

Other silage Hybrids

High sugar
Waxy
High-oil
Leafy Corn
Bmr Corn
Tropical
Sweet corn

Corn Hybrid Selection

Kinds of Corn

Specialty Corns