What factors affect test weight?

Many things can affect test weight. Some of the important factors that can influence test weight are listed below:

• Genetics of the hybrid plays an important role in test weight of the grain. Planting hybrids with genetic potential for higher test weight will generally yield grain with higher test weight if the kernels are fully mature.

• Early planting helps hybrid maturity and leads to higher test weight. Our studies for several years indicated that corn planted before May 10 had 1 to 1.5 pounds higher test weight than late May or June plantings.

• Lower grain moisture will have higher test weight since the kernel dry matter is heavier than water. Test weight is a volume-weight relationship. Drier grain shrinks and has higher test weight because we can pack more kernels into a “bushel basket.”

• Higher temperatures after the physiologic maturity or black layer tend to increase the test weight if kernels are mature.

• Drought stress tends to decrease the test weight because it affects the photosynthetic process.

• Late season leaf diseases like Northern and Southern Leaf Blight, Gray Leaf Spot, Anthracnose Leaf Blight, Goss’ Wilt and Leaf Rusts decrease the test weight since they can interrupt the grain-fill period and proper grain development.

• In the presence of leaf diseases, foliar fungicides applied during the grain-fill period may have a positive effect on test weight.

• Ear rot diseases like Diplodia, Gibberella, Aspergillus or other ear rots will have a negative effect on test weight. 
Many of our hybrids have high test weight and excellent tolerance to diseases. Make sure to ask your Seed Consultant Rep about the hybrids suitable for your farm.

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