Part 1, Section 4: Corn

Section 4 Table of Contents

A mature ear of corn

Corn

VARIETIES

Hybrids

Hybrids are available for all types of corn, and include double crosses, three-way crosses, single crosses, and modified crosses (or sister line crosses). These terms simply describe the number of inbred parent lines used in producing a hybrid and do not guarantee that one is superior to another. The merits of a hybrid rest with its genetic potential to produce grain and/ or silage.

Hybrid corn performance results are published in the annual Pennsylvania Commercial Hybrid Corn Test Reports:

Figure 1.4-1. Pennsylvania corn maturity zones and the approximate maximum relative maturity (RM) of adapted hybrids for full season grain production.

See Figure 1.4-1. These four publications are available at your local Penn State Cooperative Extension offices.

The performance of a particular hybrid may vary from location to location and from year to year. Silking dates for the hybrids being grown on a particular farm will vary, and hybrid maturity differences will increase on farms that frequently encounter drought stress. This variability has two implications for corn growers. First, you should use more than one hybrid each year. Reserve part of your acreage for evaluating new hybrids, but grow the bulk of your acreage to hybrids with which you have experience and that have a known performance record on your farm.

The second implication of the variability of hybrid performance is that hybrids should be selected on the basis of performance in a number of environments. Average performance over a wide range of environments is usually the best predictor of hybrid performance on your farm next year. As a result, two-year performance averages or average performance results from several test locations within a year increase the reliability of data on hybrid performance.

Hybrids with wide ranges of adaptability have less variation and consistently rank as superior. Although specific hybrids may adapt particularly well to some environments, these environments often are difficult to identify and usually are found after growers have had several years' experience growing a specific hybrid.

Male-sterile corn, grown for high stalk-sugar content, produces no grain and usually yields less dry matter than adapted grain-producing corn hybrids. This limits flexibility in terms of harvesting the crop for grain if needed.

To ensure a good, uniform stand, plant high-quality seed. Certified seed or seed bearing the brand tags of a reputable dealer is the best assurance of quality. Most of the seed corn is tested for germination and vigor and is of high quality.