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Crabgrass Seed Characteristics

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Crabgrass is increasingly used in planned, on purpose, forage, conservation and wildlife food systems. The initial stand may result from managing for volunteer or from planting seed of a naturalized ("native") crabgrass or the "Red River" variety.

Four crabgrass seed studies were conducted during winter-spring of 1997-98 to evaluate the feed value of seed, coating of seed for planting and influence of degree of ripeness and storage barn or soil on seed germination. We sought to obtain precise and practical information to help manage planted and volunteering stands. The following is a summary of the results of two of those studies.

Trial 1: Some wildlife managers in the southeast United States are suggesting the use of crabgrass in mixture plantings for wildlife. The reasons are many and include providing cover, grazing forage and seed feed for various wild critters. Crabgrass is good cover for quail, rabbits and other ground dwelling critters. Rabbits and other wildlife graze the forage. The seeds are among the seeds eaten by quail, rabbits and other critters.

We have tested crabgrass seed for crude protein (CP) content many times over the years. It averaged near 12% CP. Until now, we never tested the seeds (in the hull) for other chemical quality parameters. Five commercial seed samples were analyzed for a wide range of chemical and feed value contents. Results are presented in Table 1. It can be readily observed that crabgrass seeds can have substantial food value for wildlife as well as domestic livestock.

Trial 2: Some planters of crabgrass have thought that crabgrass seed planted "long" before germination time, would have earlier, more rapid germination and stand development with favorable temperature, light and moisture conditions in the spring. The thought was that cold-warm and wetdry cycles would hasten dormancy breaking of the seeds. To test this hypothesis, new harvest seed was subjected to the three treatments presented in Table 2.

Seed in the barn and associated with the soil was in small white cloth bags so temperature and moisture could readily influence it. The seed subjected to soil storage endured the natural temperature and moisture fluctuations for 74 days from February 1 to April 14. There was 1.2 inches of rain the first month, 5.3 inches the second month and no rain the last 14 days. High-low temperature ranges per month were 58-39, 60-41 and 72-49 °F.

The data of Table 2 shows a slight improvement of 15% to 17% in germination with soil storage, i.e., on surface or 0.5 inch deep under the natural conditions. While that is an improvement, it was slight. However, in this case, even the fresh seed stored in the barn had a 90% germination of all live seed. This idea needs more testing with seed of a higher rate of seed dormancy.

It seems that simply "time" is as important as temperature and moisture fluctuation to break seed dormancy. Some other seed lots stored in barns may be about 50% germination the first year and over 90% in year two. "The tincture of time" does work sometimes.