HERBICIDE CHLORSULFURON DECREASES GROWTH OF FINE ROOTS AND MICRONUTRIENT UPTAKE IN WHEAT GENOTYPES

Two Triticum aestivum (Excalibur and Catcher) and one Triticum turgidu m conv. durum (Durati) genotypes (differing in the ability to grow and yield well in environments with low Zn availability) were grown in ch elate-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 th an 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 e xposure (14-18-d-old plants) and completely inhibited growth of these roots for the remaining 6 d of exposure. The Zn-efficient genotype Exc alibur 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 tw o, non-efficient genotypes regardless of plant age or Zn nutrition, Ch lorsulfuron tended to decrease net uptake of Cu and Mn in all three ge notypes, and net uptake of Zn in Catcher and Durati, regardless of the duration of exposure, In contrast, 6-10 d of exposure to chlorsulfuro n were required for a reduction in net Zn uptake by Zn-efficient Excal ibur, In conclusion, chlorsulfuron affects the growth of fine roots an d interferes with micronutrient uptake per unit of wheat root, The inh erent trait of having a longer length of the roots with diameters less than or equal to 0.2 mm lessens the deleterious impact of chlorsulfur on on root growth and micronutrient uptake in Zn-efficient Excalibur c ompared to the other two wheat genotypes.