Glyphosate Applied at the Early Reproductive Stage Impairs Seed Production of Glyphosate-Resistant Hairy Fleabane

ABSTRACT: Glyphosate-resistant hairy fleabane [Conyza bonariensis (L.) Cronq.] is one of the most important weeds in the world. Among the factors that make this weed species widely distributed in the most diverse environments is the high seed production capacity and dispersal. Hairy fleabane plants not controlled by herbicide application regrowth and overcome crop canopy, use environmental resources, interfere with crops, and complete their life cycle by producing thousands of seeds and replenishing the seed bank. Management strategies that reduce production and viability of hairy fleabane seeds can be adopted within the integrated management to reduce the seed bank and prevent further infestations. In this way, experiments were carried out in a greenhouse and laboratory of seed analysis to evaluate the effect of glyphosate (1,480 g a.e. ha-1) on the production and viability of glyphosate-resistant hairy fleabane seeds when applied at the vegetative and reproductive stages. Seed production was reduced by 68.4 and 100% when glyphosate was applied on hairy fleabane plants at the vegetative and early reproductive stages, respectively, regarding to the control. The viability of hairy fleabane seeds was not influenced by treatments at the evaluated stages. However, glyphosate treatment reduced the hairy fleabane seed production when applied at the vegetative stage . Hairy fleabane seed production is not feasible when glyphosate is applied at the early reproductive stage.

摘要：抗草甘膦毛茎白酒草[Conyza bonariensis (L.) Cronq.]是全球范围内最重要的恶性杂草之一。该杂草可在多样生境中广泛分布的关键因素之一，便是其极高的种子生产能力与扩散能力。未被除草剂防控的毛茎白酒草植株会重新萌发并穿透作物冠层，攫取环境资源，干扰作物生长，并通过产生数千粒种子补充种子库，从而完成其完整生活史。可在综合防治体系中采用降低毛茎白酒草种子生产与活力的管理策略，以缩减种子库规模并阻止后续杂草侵染。为此，研究人员在温室与种子分析实验室中开展试验，评估在营养期与生殖期喷施草甘膦（1480克酸当量每公顷对抗草甘膦毛茎白酒草种子生产与活力的影响。与对照组相比，在营养期和早期生殖期喷施草甘膦，可分别使毛茎白酒草的种子产量降低68.4%与100%。在所评估的两个喷施时期内，各处理均未对毛茎白酒草种子的活力产生影响。不过，在营养期喷施草甘膦可降低毛茎白酒草的种子产量。若在早期生殖期喷施草甘膦，则毛茎白酒草的种子生产完全不可行。