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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #161524
Title: RELATIVE FITNESS OF IMAZAMOX-RESISTANT COMMON SUNFLOWER AND PRAIRIE SUNFLOWER

Author
item MASSINGA, RAFAEL - KANSAS STATE UNIVERSITY
item AL-KHATIB, KASSIM - KANSAS STATE UNIVERSITY
item ST. AMAND, PAUL - KANSAS STATE UNIVERSITY
item Miller, Jerry

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2004
Publication Date: 3/1/2005
Citation: Massinga, R.A., Al-Khatib, K., St. Amand, P., Miller, J.F. 2005. Relative fitness of imazamox-resistant common sunflower and prairie sunflower. Weed Science. 53:166-174.

Interpretive Summary: Resistant to imidazolinone (IMI) herbicides has been recently incorporated into domesticated sunflower through conventional breeding methods. However, there are concerns regarding gene flow of the IMI-resistance trait to wild species and possible accompanying ecological consequences. Hybrids of domesticated sunflower with both common sunflower and prairie sunflower were created, with and without the imazamox resistance trait. Studies were conducted to determine the relative fitness of imazamox-resistant (IMI-R) hybrids compared to their imazamox susceptible (IMI-S) counterparts. Greenhouse experiments were conducted to study growth of IMI-R and IMI-S common and prairie sunflower hybrids under noncompetitive conditions. The photosynthesis rate of IMI-S prairie sunflower was slightly higher than IMI-R plants. The relative growth rate, net assimilation rate, plant height, leaf area, and total dry weight were similar in IMI-R and IMI-S common and prairie sunflower. A replacement series study was conducted under field conditions in 2001 and 2002 to evaluate the relative competitiveness of IMI-R and IMI-S common and prairie sunflower. The IMI-R and IMI-S hybrids of both sunflower species were equally competitive. These results suggest that, in the absence of IMI herbicides, genes controlling IMI-R do not increase or reduce the competitive ability of either common or prairie sunflower. Therefore, if the IMI-resistant trait is incorporated into these species, the frequency of IMI resistance genes is unlikely to increase or decrease, even in the absence of IMI selection pressure.

Technical Abstract: Resistant to imidazolinone (IMI) herbicides has been recently incorporated into domesticated sunflower (Helianthus annuus L.) through conventional breeding methods. However, there are concerns regarding gene flow of the IMI-resistance trait to wild species and possible accompanying ecological consequences. Hybrids of domesticated sunflower with both common sunflower and prairie sunflower were created, with and without the imazamox resistance trait. Studies were conducted to determine the relative fitness of imazamox-resistant (IMI-R) hybrids compared to their imazamox susceptible (IMI-S) counterparts. Greenhouse experiments were conducted to study growth of IMI-R and IMI-S common and prairie sunflower hybrids under noncompetitive conditions. The photosynthesis rate of IMI-S prairie sunflower was slightly higher than IMI-R plants. The relative growth rate, net assimilation rate, plant height, leaf area, and total dry weight were similar in IMI-R and IMI-S common and prairie sunflower. A replacement series study was conducted under field conditions in 2001 and 2002 to evaluate the relative competitiveness of IMI-R and IMI-S common and prairie sunflower. The IMI-R and IMI-S hybrids of both sunflower species were equally competitive. These results suggest that, in the absence of IMI herbicides, genes controlling IMI-R do not increase or reduce the competitive ability of either common or prairie sunflower. Therefore, if the IMI-resistant trait is incorporated into these species, the frequency of IMI resistance genes is unlikely to increase or decrease, even in the absence of IMI selection pressure.