Weed Suppressive Rice Cultivars
• Weeds are the most costly pest of rice production
• Herbicides are applied to most rice fields each year to control weeds
• Weed-suppressive rice can reduce herbicide use and benefit the environment
• Weed suppression may be due to rice root growth, height and tillering,
or natural herbicides produced by the rice roots (allelochemicals)
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Under low weed populations,
rice varieties show dramatic
differences in suppression.
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Rice plots planted in barnyardgrass-infested field. Weed-suppressive rice
varieties (two photos at right) dramatically reduce weed population and
growth when plants are young. This suppression can continue through
maturity.
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Red Rice Outcrossing
- Red rice is a Crop 'mimic' that reduces yield, and produces undesirable
red seeds. Both are the species Oryza sativa.
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Rough
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De-Hulled
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Milled
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| Strawhull Red Rice
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| Awned Red Rice
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Long-grain Rice
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Medium-grain Red Rice
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Rice X Red Rice Hybrid (medium-grain)
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X
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Year 1: Rice (dark green) and red rice (light green) are grown together
to allow plants to outcross as they would in a farm field.
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Year 2: Rice X awned blackhull red rice hybrids produce pink awns.
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Year 2: Rice X awnless strawhull red rice hybrids flower very late (or
not at all) and are awnless.
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Year 2: Clearfield rice crosses at low rates with red rice. This produces
small numbers of Herbicide-resistant hybrids that we confirm using DNA
fingerprinting.
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In this photo you can see remnants of the dead non-hybrids below the water's
surface. These were killed with herbicide.
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Research Support Staff:
Dr. David Gealy, USDA ARS, Research Plant Physiologist
Howard Black, USDA ARS, Plant Physiologist, Support Scientist
Gordon Miller, USDA ARS, Biological Science Technician
Galen Branch, University of Arkansas, Service Assistant
Kimberly Buffkin, University of Arkansas, Service Assistant
Major Cooperators:
Nilda Burgos, University of Arkansas, Fayetteville
Karen Moldenhauer, University of Arkansas, Stuttgart
John Mattice, University of Arkansas, Fayetteville
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