Abstract Background Cutleaf geranium ( Geranium dissectum L) is a weed found in cereals and grasslands. Knowledge about the germination response of weeds under various environmental conditions is critical for their effective management, whereas such study has not been carried out thoroughly on this species. Objective This study was carried out to investigate the effect of some environmental factors on seed germination and emergence of cutleaf geranium. Methods The seeds were subjected to various environmental factors including water potentials, salinity, pH, high temperatures, burial depth and flooding at the temperature resulting in the highest germination (10 °C). All experiments were carried out twice, which were done consecutively. Results Germination percentage was halved at a water potential of -0.6 MPa, and no germination was observed at -2 MPa. Geranium dissectum seeds had negligible germination at 200 mM NaCl concentration. Seeds germinated over a pH range of 5-8, with the highest germination at pH between 6 and 7. Germination of this species reached from 85.0% after treatment at 80 °C but no seeds germinated after exposure to 120 °C. Maximum emergence was estimated 88.8%, which was halved at 2.2 cm depth. No emergence was observed at 4 cm or greater depths. Germination was 88.4% to 0% 15 days after flooding. Conclusions This species may not usually be found in areas with poor environmental conditions, and a semi-deep tillage or inclusion of rice in crop rotation may be used to control this weed.

Abstract Background Among the weeds in Iran, resistant Lolium rigidum Gaud is considered a troublesome weed in winter cereals due to its tendency to evolve cross (CR) and multiple resistance (MR) to herbicides. Objective This research examined the patterns and mechanisms of L. rigidum resistance to clodinafop-propargyl (CP) and mesosulfuron methyl+iodosulfuron methyl (MI). Methods Experiments were conducted on four putative-resistant L. rigidum biotypes and one susceptible biotype. The dose-response assay was performed on the biotypes with CP and MI. CR and MR were investigated with haloxyfop-R-methyl (HRM), sethoxydim (SD), pinoxaden (PN). and isoproturon+ diflufenican (ID) herbicides. An indirect study of the metabolism of herbicides was carried out using the cytochrome P450 monooxygenase (CYP450) inhibitors 1-aminobenzotriazole (ABT), piperonyl butoxide (PBO) and malathion. Finally, sequencing of ALS and ACCase genes was performed to investigate target-site resistance. Results All putative-resistant L. rigidum biotypes were resistant to CP, MI, and HRM, but susceptible to SD, PN, and ID. The indirect study showed that the P450 enzyme had no role in the evolution of resistance in L. rigidum biotypes. Resistance in this species was due to Ile-1781-Leu and Pro-197-Ser substitutions on ACCase and ALS encoding genes led to resistance, respectively. Conclusions Resistance in the studied L. rigidum biotypes to ALS and ACCase inhibiting was due of target site resistance. If these resistant biotypes are not controlled, they will become a problem for farmers in the region.