Seed Dormancy – The Uncertainty in Native Grass Seeding

by Terry M. Conway, Plant Materials Specialist
Natural Resources Conservation Service (NRCS)
Salina, Kansas

Native grasses have survived in nature without any form of cultivation for thousands of years. Their ability to survive and flourish results from several protective mechanisms provided by Mother Nature. These protective mechanisms, however, may interfere with the speed and/or uniformity of their establishment. One of these mechanisms is seed dormancy.

Seed dormancy is basically a physical or genetic characteristic that prevents the seed from germinating. The purpose of dormancy is to allow the seed to germinate and the plant to establish under favorable growing conditions. The proportion of dormant seed in native warm-season grasses depends on physical and genetic factors. Some species, even some varieties within a species, produce more dormant seed than others do.

Age of the seed has been proven to be a factor in affecting the percent of seed dormancy. Newly harvested seed will many times have more dormant seed than seed that has been stored for several months. In fact, for many native warm-season grass species, the actual germination of the seed will increase with age due to the loss of dormancy with time. For example, a seed storage study being conducted at the NRCS Manhattan Plant Materials Center has shown that ‘Kaw’ big bluestem had an initial germination of 63 percent that increased to 88 percent after 15 years of proper storage, ‘Blackwell’ switchgrass increased from 85 percent to 98 percent, ‘Aldous’ little bluestem increased from 70 percent up to 81 percent, and ‘Osage’ Indiangrass increased from 75 percent to 88 percent.

Seed dormancy is also affected by cold, moist conditions. Germination tests performed by seed laboratories have indicated that cold, moist treatments of some of the warm-season native grasses have resulted in improved germination. One example showed a variety of switchgrass not treated with cold, moist conditions had a germination of 15 percent and 70 percent dormant seed. Material from the same lot that was subjected to the cold, moist conditions had 80 percent germination and 5 percent dormant seed. This suggests that earlier planting dates may allow Mother Nature to provide the treatments necessary for a higher percentage of the seed to germinate and survive the first growing season.

Seed dormancy does exist in native warm-season grasses; therefore, the speed and/or uniformity of establishment are not always predictable. Native grass plantings have in many cases been prematurely judged as failures and destroyed because of a lack of understanding of seed dormancy and the effect on timing of seedling emergence.

For more information about native grass seeding, please contact your local Natural Resources Conservation Service office or conservation district office located at your local county USDA Service Center. For more information about plant materials, visit the http://plant-materials.nrcs.usda.gov Web site.

For more information about NRCS programs, visit the Kansas NRCS Web site at www.ks.nrcs.usda.gov.

This article is also available in Microsoft Word format.

Seed Dormancy – The Uncertainty in Native Grass Seeding (DOC; 35 KB)

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Last Modified: 09/04/2008