Greenhouse trials were conducted to determine Hooker's evening primrose transplant tolerance to POST-applied herbicides. Herbicide treatments consisted of glyphosate at 1.68 kg ae ha−1, glufosinate at 0.84 kg ai ha−1, fenoxaprop at 0.10 kg ai ha−1, fluazifop at 0.45 kg ai ha−1 + a nonionic surfactant (NIS) at 0.25% v/v, sulfosulfuron at 0.06 kg ai ha−1 + NIS at 0.25% v/v, quinclorac at 0.42 kg ae ha−1 + methylated seed oil (MSO) at 0.5% v/v, mesotrione at 0.21 kg ai ha−1, and the combination of quinclorac + mecoprop + dicamba at 0.42 + 0.21 + 0.06 kg ae ha−1 + MSO at 0.5% v/v. Fluazifop (14%) and fenoxaprop (19%) treatments did not result in any significant phytotoxicity 7 d after treatment (DAT) compared with the nontreated check. Hooker's evening primrose exhibited 26 to 37% phytotoxicity in response to quinclorac, glyphosate, or sulfosulfuron 7 DAT. Phytotoxicity ≥ 50% was observed for mesotrione, glufosinate, and the combination of quinclorac + mecoprop + dicamba 7 DAT. Phytotoxicity increased for all treatments 28 DAT. Fluazifop (21%) was the only treatment that did not exhibit phytotoxicity symptoms different from the nontreated check 28 DAT. Hooker's evening primrose exhibited 31 to 40% phytotoxicity with applications of fenoxaprop, glyphosate, or glufosinate 28 DAT. Phytotoxicity was ≥ 58% with all other treatments 28 DAT. Fluazifop exhibited similar above-ground (12.4 g) and below-ground (16.4 g) biomass as the nontreated check (10.8 and 14.7 g, respectively) 28 DAT. All other treatments resulted in 1.6 to 5 g of above-ground biomass and 0.8 to 4.3 g of below-ground biomass 28 DAT. Fluazifop (24.3) and fenoxaprop (18.8) applications resulted in a plant growth index (PGI) that was not significantly different from the nontreated check (24.7) 28 DAT. A PGI ≤ 16.2 was observed for all other treatments 28 DAT.

Vavilov (1935) described China as the earliest and largest independent centre of origin of cultivated plants. Gansu Province occupies the geographic centre of China. With an area of 454,000 km2, latitudes ranging from 32°3′N to 42°57′N and elevations varying from 500 to 6200 m, the province has an extremely diverse climate and topography. Stretching 1653 km along the ancient Silk Road, Gansu also has a long history of agriculture (6000 years) and for centuries was exposed to dynamic cultural exchanges between the East and the West. The unique combination of these conditions allowed rapeseed to be introduced from Europe and the Middle East, to evolve over a long time of cultivation and to diversify to adapt to many types of ecological conditions and cropping systems in Gansu. Currently, rich genetic resources exist in Gansu for Brassica rapa, B. juncea, B. chinensis and Eruca sativa. Eight landraces are described to demonstrate the diversity of rapeseed genetic resources in Gansu. It is generally recognized that B. chinensis originated in China. Information provided in this paper suggests that Gansu and its adjacent regions could also be a centre of diversity for B. rapa and B. juncea.