Sensitivities of spring wheat cultivars to chlorsulfuron measured as inhibitions of leaf elongation rates and there were genotype multiply environment interactions

Abstract

Inhibitions of the rates of elongation of the third leaf of seedlings of spring wheat (ARLE3) were used to identify differences in cultivar sensitivities to chlorsulfuron. The standard test was 408g chlorsulfuron/kg sandy soil, pH 6.2, high nitrogen and phosphorus nutrition and 2O¦C/15¦C (day/ night). Timstein and Gabo were found to be the most tolerant cultivars with -RLE3s of 4 and 5 mm day-1 (9 and 11 % of untreated RLE3) and Sonora and Miling the most sensitive with -RLE3s of 19 and 21 mm day-1 (45 and 48% of untreated RLE3s); 16 cultivars were intermediate with -RLE3s of 9-15 mm day-1 The cultivars most sensitive to chlorsulfuron were semi-dwarf types carrying the Rht/ Gai genes for stature/insensitivity to gibberellic acid. There were significant genotype x environment interactions; Sonora treated with chlorsulfuron failed to respond to increases in soil nitrogen and phosphorus, and sensitivity was increased at temperatures below 20¦C. The -RLE3 test was simple, rapid and non-destructive, and may be suitable for use by plant breeders. Identification of genotypes sensitive to chlorsulfuron based on inhibitions of grain yield would be more protracted and less efficient than those based on -RLE. The herbicide was degraded and leached in the field plots with 0.4 8g chlorsulfuron/kg soil found at 40 cm in the profile 8 weeks after application.