the influence of ammonium nitrate on antagonism of spray tank sodium bicarbonate on glyphosate and nicosulfuron performance on barnyard - grass and velvetleaf

the influence of ammonium nitrate (amn) on antagonism of sodium bicarbonate (nahco3) in spray tank of glyphosate (roundup®, 41% sl) and nicosulfuron (cruse®, 4% sc) on barnyard-grass [echinochloa crus-galli (l.) p. beauv.] and velvetleaf (abutilon theophrasti medicus.) control were examined in greenhouse studies as a factorial arrangement of treatments 6×2 based on a completely randomized design with six replications (+six control pots) for each weed species at ferdowsi university of mashhad, iran during 2009-10. factors were included: sodium bicarbonate (merck, germany) at six levels (0, 100, 200, 300, 400, 500, and 600 ppm into deionized water (w/v)) in combination with 0 or 0.5 kg/ha amn (merck, germany) as modulator the alkalinity. the herbicide solutions were applied as post emergent at the 3-4 leaf stage of the weeds at the estimated ed50 doses at greenhouse in the preliminary experiment (22, and 158 g a.i. ha-1 for nicosulfuron and glyphosate herbicides, respectively) in a spray volume 250 l ha-1. the results showed the significant effect (p≤0.01) of nahco3 for survival, height, leaf area, and shoot dry weight (% control) four weeks after herbicides application. amn added to the spray tank decreased significantly (p≤0.01) the adverse effects of water alkalinity, and increased herbicides efficacy on barnyard-grass and velvetleaf, whereas increasing of nicosulfuron efficacy on barnyard-grass control, and glyphosate efficacy on velvetleaf control were highlight, respectively. in conclusion, the results of this experiment have highlighted the importance of amn in overcoming to the antagonistic effect of spray tank nahco3 on glyphosate and nicosulfuron efficacy.