Comparison of the response of seedlings of common buckwheat (Fagopyrum esculentum Moench) to glyphosate applied to the shoot or to the root zone

We examined the response of common buckwheat (Fagopyrum esculentum Moench) seedlings, as a nontarget plant, to various doses of glyphosate applied to the root zone or to the shoots. Glyphosate was used at 0.1, 0.5, and 1.0 mM concentrations. The study was conducted on seedlings grown in hydroponic cultures under controlled growth conditions. Primary root and shoot growth, anthocyanin and photosynthetic pigment contents were measured to assess the effects of exposure to glyphosate. Glyphosate applied to shoots had a considerably higher impact on the growth of primary roots and shoots of seedlings. Low glyphosate concentrations produced an increase in anthocyanin content of hypocotyls, regardless of the mode of its application. Increasing the concentration of glyphosate applied to the root zone resulted in a gradual increase in anthocyanin content in cotyledons. Our overall results show that in hydroponically grown common buckwheat seedlings, glyphosate is less phytotoxic when applied to the root zone than when applied to the shoot. Low doses of glyphosate applied to the root zone stimulate root and shoot growth and increase the anthocyanin levels in cotyledons. The phytotoxicity of glyphosate was decreased in the absence of mineral nutrients in the root zone of buckwheat seedlings.