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Multiple Herbicide Resistance in Wild Oat and Impacts on Physiology, Germinability, and Seed Production
Author(s) -
Lehnhoff Erik A.,
Keith Barbara K.,
Dyer William E.,
Peterson Robert K.,
Menalled Fabian
Publication year - 2013
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2012.0428
Subject(s) - biology , population , acetolactate synthase , avena fatua , agronomy , weed , germination , transpiration , herbicide resistance , botany , photosynthesis , biochemistry , demography , sociology , gene
The evolution of weed biotypes resistant to multiple herbicide modes of action, here termed multiple herbicide resistance , is a growing problem around the world. We investigated two multiple herbicide resistant (MHR) wild oat ( Avena fatua L.) populations from Montana and hypothesized that they would exhibit fitness costs compared with two herbicide‐susceptible (HS) populations. Dose‐response tests showed that the MHR populations were resistant to difenzoquat (a membrane disruptor), imazamethabenz (an acetolactate synthase [ALS] inhibitor), flucarbazone (an ALS inhibitor), and tralkoxydim (an acetyl‐CoA carboxylase inhibitor). In greenhouse studies, we assessed differences between MHR and HS populations in seed germination, photosynthetic parameters, plant growth, and reproduction. Seeds of one HS population germinated more at cold temperature (4.9°C) and less at high temperature (29.6°C) compared with the other populations. Plants of this HS population also had lower stomatal conductance (23%), intercellular CO 2 concentration (7.5%), and transpiration (15.3%) than the other populations, but there were no differences in photosynthetic rates between any populations. Also, there were no differences in relative growth rate among all HS and MHR populations. The MHR populations initiated seed production several days sooner than the HS populations; however, HS populations produced 67% more tillers, and one HS population ultimately produced 43% more seeds than the MHR populations, indicating a potential fitness cost of resistance. With the exception of seed production differences, our results do not indicate a consistent fitness cost. More research is needed in field settings and with resource competition to further evaluate fitness costs in MHR populations.