Higher seeding rates and larger seed sizes could enhance the competitiveness of
wheat with ryegrass. Growth room and field research evaluated the effects of wheat
seeding rates and seed size in competition with Italian ryegrass. Winter wheat seeds
cultivar “Ogallala” were divided into three seed sizes: small seed passed through a sieve
with 2.08mm round holes, large seed which did not pass through a sieve with 3.18mm
round holes, and bulk seed directly from a commercial seed bag.
These wheat seed and seed of the Italian ryegrass cultivar AGulf@ were planted in
plastic pots containing fritted clay. A replacement series design with 12 plants per pot
compared the relative growth in pure culture and competitiveness in mixtures of the two
species. The planting proportions of each wheat seed group and ryegrass were 100% and
0%, 50% and 50%, and 0% and 100%, respectively. Wheat seed size did not affect the
growth of the wheat plants in pure culture. Wheat seed size did not affect
competitiveness with ryegrass. There were no differences related to seed size among the
pure or mixed cultures of wheat. The failure of increased wheat seed size to affect
competition with ryegrass may be the result of the relative seed size difference between
the two species. Even the small wheat seed in this study were almost 9-fold greater inweight than the ryegrass seed.
Field experiments conducted for two years from fall 2002 through spring 2004 at
the Texas A&M University Agronomy Farm measured wheat yields at the same three
wheat seed sizes, two wheat densities of 250 plants m-2 and 400 plants m-2, and three
ryegrass densities of 0, 100 and 200 plants m-2. Small, bulk, and large wheat seed
produced similar yields in both years: one season favorable (2003) for growth and the
other (2004) unfavorable. Thus, seed size in the field under favorable or unfavorable
conditions or in the growth room experiment did not affect the competitiveness of wheat
in the presence of ryegrass. Increasing the wheat plant population from 250 to 400 plants
m-2 in the field also failed to enhance the competitiveness of wheat in either year.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/2284 |
| Date | 29 August 2005 |
| Creators | Cook, Casey Lee |
| Contributors | Cralle, Harry |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 216301 bytes, electronic, application/pdf, born digital |
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