Abstract
Echinochloa crusgalli (L.) Beauv. (barnyard grass) is considered a noxious weed worldwide, and is the most pernicious weed decreasing rice yields in China. Recently, E. crusgalli has evolved quinclorac resistance, making it among the most serious herbicide resistant weeds in China. The present study explored differences in germination and growth between quinclorac-resistant and -susceptible E. crusgalli collected in Hunan Province. The order of the seven E. crusgalli biotypes assessed, from high to low quinclorac-resistance, was: quinclorac-resistant, Chunhua, Hanshou, Shimen, Hekou, Dingcheng, and quinclorac-susceptible. With an increased in the level of quinclorac-resistance, the germination rate, length of young shoots and roots, and fresh weight of E. crusgalli were all decreased compared with that in more susceptible biotypes. However, there were no significant differences between quinclorac-resistant and susceptible E. crusgalli biotypes without polyethylene glycol 6000 treatment. Drought had a more obvious effect on glutathione S-transferases (GST) activity, determined by spectrophotometric method, in quinclorac-resistant E. crusgalli. Higher resistance level biotypes showed greater activity, and when treated with polyethylene glycol 6000 for 3 days, all E. crusgalli biotypes showed the highest GST activity. This study demonstrated that as the level of quinclorac-resistance increased, the rate of seed germination decreased, while the growth of young buds, young roots, and fresh weight decreased. Increased quinclorac-resistance may be related to the increased metabolic activity of GST in E. crusgalli.
Highlights
Echinochloa crusgalli (L.) Beauv., a C4 plant [1], is regarded as the most dominant and troublesome weed in rice fields [2]
Echinochloa crusgalli seeds used in this study were collected in 2013 from two adjacent rice fields in Chunhua, Hunan Province
A large difference in quinclorac resistance was observed among the seven E. crusgalli biotypes (Table 1)
Summary
Echinochloa crusgalli (L.) Beauv. (barnyardgrass), a C4 plant [1], is regarded as the most dominant and troublesome weed in rice fields [2]. (barnyardgrass), a C4 plant [1], is regarded as the most dominant and troublesome weed in rice fields [2]. It competes with rice for water, light, and soil nutrients [3,4] and has a severe impact on rice yield and quality [5]. Echinochloa crusgalli is one of the most common weeds found in Chinese farmland [6]. Its seeds can germinate under an anaerobic environment, germinate and mature rapidly, and be produced in large numbers [7,8].
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