Herbicide chlorsulfuron decreases growth of fine roots and micronutrient uptake in wheat genotypes

Two Triticum aestivum (Excalibur and Catcher) and one Triticum turgidum conv. durum (Durati) genotypes (differing in the ability to grow and yield well in environments with low Zn availability) were grown in chelate-buffered, complete nutrient solutions providing either deficient or sufficient Zn supply and supplemented with sulphonylurea herbicide chlorsulfuron [2-chloro-N-(((4-methoxy-6- methyl-1,3,5-triazin-2-yl) amino)carbonyl)-benzenesulphonamide] at 0 or 4 mg m(-3) Compared to Zn-sufficient roots, plants grown under Zn deficiency had thicker roots on average, with a shorter length of the fine roots (diameters less than or equal to 0.2 mm), Chlorsulfuron decreased growth of roots in the less than or equal to 0.2 mm diameter class during the first 4 d of exposure (14-18-d-old plants) and completely inhibited growth of these roots for the remaining 6 d of exposure. The Zn-efficient genotype Excalibur maintained a longer length of roots with diameters less than or equal to 0.2 mm and had a greater root surface area than the other two, non-efficient genotypes regardless of plant age or Zn nutrition, Chlorsulfuron tended to decrease net uptake of Cu and Mn in all three genotypes, and net uptake of Zn in Catcher and Durati, regardless of the duration of exposure, In contrast, 6-10 d of exposure to chlorsulfuron were required for a reduction in net Zn uptake by Zn-efficient Excalibur, In conclusion, chlorsulfuron affects the growth of fine roots and interferes with micronutrient uptake per unit of wheat root, The inherent trait of having a longer length of the roots with diameters less than or equal to 0.2 mm lessens the deleterious impact of chlorsulfuron on root growth and micronutrient uptake in Zn-efficient Excalibur compared to the other two wheat genotypes.