Tolerance to selective and non-selective herbicides by conventional and genetically-modified sugar beet

In a greenhouse experiment a conventionally bred and a genetically modified (GMO) sugar beet variety were compared with regard to their tolerance to a selective (Betanal Progress EC; BP) and a nonselective (Liberty) herbicide , respectively. After the application of Liberty, the Liberty-tolerant beet s showed some chlorotic leaf spots, especially after higher dosages, but th ese spots became only partially necrotic. At all application rates tested, BP led to necrotic leaf spots which increased in number and intensity with increasing application rates, but no losses of plants were observed. The ap plication of Liberty in highest amounts led to a 25% reduction in calculate d white sugar yield (WSY) when compared with an untreated control. After th e application of BP at the same dosage, the WSY was only half for both vari eties in comparison with the control. Different tissues contained the enzym e phosphinothricin-acetyl-transferase (PAT) in different amounts.