Environmental factors affecting absorption and bio-efficacy of glyphosate in Florida beggarweed (Desmodium tortuosum)
2001
Sharma, S.D. | Singh, M.
Experiments were conducted in controlled growth cabinets to examine the effect of air temperature (16 degrees C, 22 degrees C, 35 degrees C) or relative humidity (RH 45%, 70%, 95%) on 14C-glyphosate distributions in Desmodium tortuosum and bio-efficacy. Uptake and translocation of 14C-glyphosate were significantly higher at 22 degrees C or 95% RH than 16 degrees C and 35 degrees C or 45% and 70% RH at all harvest times. These values were also significantly higher when influence of temperature or RH recorded when the effects across harvest times (6, 24, 48, 72 h) were averaged. Further, uptake and translocation were significantly higher at 48 h than the other harvest time when the effects across temperatures (16 degrees C, 22 degrees C, 35 degrees C) were averaged. Maximum translocation was obtained at 72 h harvesting time when the effects of RH (45%, 70%, 95%) were averaged. When glyphosate was sprayed to beggarweed, the maximum foliar damage was observed 19% at 22 degrees C or 35 degrees C and 23% at 95% RH. Bioefficacy results were similar to 14C-glyphosate translocation at 22 degrees C and 95% RH. The results indicated that temperature or RH influenced the absorption process of glyphosate and the optimum temperature and relative humidity for Desmodium control were 22 degrees C and 95% RH.
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