A promising method for selecting imazamox-resistant sunflower plants

Abstract

This study was conducted to investigate the potential of using the germination test as a model for screening imazamox resistance in sunflower plants . A standard germination test was performed by applying different doses of imazamox (control, 0.1, 0.2, 0.4, 0.8, and 1.6 mM) to imidazoline-resistant (IMI-R) and susceptible (IMI-S) sunflower hybrids. Germination percentage, mean germination time, germination index, shoot length, root length, seedling fresh and dry weight, and phytotoxicity percentage for seedling growth parameters were investigated. The results showed that imazamox concentrations slightly affected the germination percentage of two sunflower hybrids at only 1.6 mM. Increasing doses of imazamox led to an increase in the mean germination time and a decrease in the germination index for both sunflower hybrids, following a similar trend. Seedling growth parameters such as shoot length, root length, and seedling fresh weight were significantly decreased by increasing imazamox doses. In addition, the differences between IMI-R and IMI-S sunflower hybrids were very evident for these parameters. The IMI-S sunflower hybrid showed sensitivity in the presence of imazamox, while no changes in the IMI-R hybrid were determined up to 0.4 mM. The inhibition percentage was higher in the IMI-S hybrid than in the IMI-R. It was concluded that the optimal dose of imazamox for the selection of resistant plants during the early growth stage was found to be 0.2 mM. The germination parameters were not good criteria for imazamox resistance, while root length, shoot length, and seedling fresh weight should be considered as selection criteria for resistance to imazamox in sunflower.