Pre-selection of Imidazolinone-Resistant Canola Plants by Germination and Subsequent Seedling Growth Parameters

This study aimed to investigate the potential use of the germination test as a model for screening canola plants for herbicide resistance. Imidazoline-resistant (IMI-R) and susceptible (IMI-S) canola hybrids were germinated in various concentrations of imazamox (0, 0.25, 0.50, 1.00, and 2.00 mM) and clopyralid (0, 0.21, 0.43, 0.85, and 1.72 mM). Germination percentage, mean germination time, germination index, shoot length, root length, seedling fresh and dry weight, and dry matter were analyzed. The results indicated that varying concentrations of imazamox and clopyralid had only a limited effect on the germination parameters in canola hybrids. However, seedling growth parameters such as shoot length, root length, and seedling fresh weight were significantly reduced with increasing concentrations of imazamox and clopyralid. Notably, the differences between IMI-R and IMI-S canola hybrids were evident for these parameters. IMI-S canola hybrid exhibited sensitivity to imazamox, while the IMI-R hybrid showed no significant reduction in growth up to 0.50 mM imazamox. Conversely, the shoot length of the IMI-S hybrid was less affected and was longer than that of the IMI-R hybrid under clopyralid treatment. Of the parameters investigated, root length was the most sensitive to imazamox, which can be used to select herbicide resistance. It was concluded that the suitable imazamox concentrations for selecting imazamox-resistant canola plants during the early growth stage were between 0.50 mM and 1.00 mM. Germination parameters were found to be unsuitable criteria for imazamox resistance, while root length, shoot length, and seedling fresh weight should be considered for selection.