Differential tolerance may be observed among rice cultivars with desiccant exposure events during rice reproduction and ripening. Five field studies were established at the Mississippi State University Delta Research and Extension Center in Stoneville, MS, to determine the effects of exposure to sublethal concentrations of common desiccants across multiple rice cultivars. Rice cultivars in the study were ‘CLXL745’, ‘XL753’, ‘CL163’, ‘Rex’, and ‘Jupiter’. Desiccant treatments included no desiccant, paraquat, or glyphosate and were applied at the 50% heading growth stage respective to cultivar. Differential injury estimates among cultivars and desiccant treatments was observed when glyphosate or paraquat was applied at 50% heading. Injury from glyphosate at 50% heading was nondetectable across all cultivars. However, injury following paraquat applications was >7% across all rating intervals and cultivars. Hybrid cultivars exhibited less injury with paraquat applications than the inbred cultivars in the study. Rice following exposure to glyphosate or paraquat at 50% heading growth stage produced rough rice grain yield decreases ranging from 0% to 20% and 9% to 21%, respectively. Rough rice grain yield decreases were observed across all cultivars following paraquat exposure, and all inbred cultivars following glyphosate exposure. Across desiccant treatment, head rice yield was reduced in three of five cultivars in the study. When pooled across cultivar, paraquat applications cause a head rice yield reduction of 10%, whereas rice yield following glyphosate application remained >95%. Although differential tolerance among cultivars to paraquat or glyphosate exposure was observed, impacts on grain quality coupled with yield reductions suggests extreme rice sensitivity to exposure to sublethal concentrations of these desiccants at the 50% heading growth stage.

中文翻译：

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水稻品种在季节后期对亚致死浓度的草甘膦和百草枯的反应

在水稻繁殖和成熟过程中，可能会在具有干燥剂暴露事件的水稻品种中观察到差异耐受性。在密西西比州斯通维尔的密西西比州立大学三角洲研究和推广中心开展了五项实地研究，以确定暴露于亚致死浓度的常见干燥剂对多个水稻品种的影响。研究中的水稻品种是“CLXL745”、“XL753”、“CL163”、“Rex”和“Jupiter”。干燥剂处理包括不使用干燥剂、百草枯或草甘膦，并在各品种抽穗生长期的 50% 时施用。当草甘膦或百草枯以 50% 的抽穗率施用时，观察到栽培品种和干燥剂处理之间的不同伤害估计。在所有品种中，50% 抽穗时草甘膦造成的伤害均未检测到。然而，在所有评级区间和品种中，百草枯施用后的伤害均 > 7%。与本研究中的自交品种相比，使用百草枯的杂交品种表现出更少的伤害。水稻在抽穗生长期暴露于草甘膦或百草枯后，糙米产量分别下降 0% 至 20% 和 9% 至 21%。暴露于百草枯后所有品种和暴露于草甘膦后的所有自交品种均观察到糙米产量下降。通过干燥剂处理，研究中五个品种中的三个降低了整粒稻产量。当跨品种合并时，百草枯施用导致整粒稻产量减少 10%，而施用草甘膦后的稻米产量保持 > 95%。