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Techniques for selecting wheat lines tolerant to imidazolinone herbicides
The purpose of this research was to develop a breeding protocol that can be used to specifically transfer and select imidazolinone herbicide tolerant wheat lines in segregating populations for the FS2 gene that confers imidazolinone herbicide tolerance in wheat (Triticum aestivum L.). A preliminary study found that most of Nebraska winter wheat cultivars are lacking any tolerance for imazamox herbicide in the seedling stage. Two field studies in consecutive years (2000 and 2001) in Lincoln, Nebraska and screening experiment in the greenhouse for heads taken from the segregating populations after different imazamox herbicide treatments showed that using the 2x rate of imazamox herbicide where x is the recommended herbicide rate in the field 45 g ai/ha of imazamox herbicide is the appropriate rate to remove all of the homozygous susceptible and most of the heterozygous plants without noticeable adverse affects on the homozygous tolerant plants. ^ Using the 2x rate in an early generation in the segregating populations successfully selects for herbicide tolerance and this would allow plant breeders to select for other agronomic and quality traits in following generations. One herbicide selection treatment was needed to effectively select herbicide tolerant plants. However, two selection treatments would add an additional level of confidence should a single herbicide treatment not be completely effective (i.e. some heterozygous plants survived). Treating segregating populations for FS2 gene with 2x of imazamox herbicide causes plants to die and hence reduced plant density. Like many other studies in wheat, reduction of plant density caused a delay in flowering; and a reduction in plant height, grain yield, and grain volume weight. However once the susceptible and heterozygous plants are removed, the populations after spraying have full stand density and can be treated as ‘normal’ population for agronomic selection. ^
Al-Otayk, Soleman Mohamed, "Techniques for selecting wheat lines tolerant to imidazolinone herbicides" (2002). ETD collection for University of Nebraska - Lincoln. AAI3074063.