Influence of high soil temperature, ammonium ion, and rapeseed residue on trifluralin phytotoxicity to wheat

The combination of high soil temperature (36 °C) with trifluralin caused spring wheat (Triticum aestivum L. ’Neepawa’) seedlings to have shortened coleoptiles that failed to emerge above the soil surface. This resulted in damaged primary leaves due to abrasion in the soil layers. Evidence is presented that rapeseed (Brassica napus L. ’Regent’) residues have phytotoxic effects on wheat seedlings. High soil ammonium ion concentrations did not affect trifluralin phytotoxicity. All results indicated that the potentially damaging effects of high soil temperature and rapeseed residue are independent of, but additive to, those of trifluralin.Key words: Temperature, ammonium ion, rapeseed, trifluralin, wheat