Saffron Crocus sativus L. tolerance to some herbicides

Although, weed control in saffron farms is critical, no herbicide is registered for saffron fields. This experiment was carried out in a randomized complete block design with three replicates during 2016-2017. Treatments included application of trifluralin, pendimethalin, metribuzin, bentazon, ioxynil, oxadiazon, oxyfluorfen, haloxyfop-r-methyl, sethoxydim, clethodim, cycloxydim, nicosulfuron, rimsulfuron, tribenuron methyl, foramsulfuron, paraquat, dicamba + triasulfuron, and dicamba + tritosulfuron herbicides at recommended and reduced doses. Mother corms were planted on 10th of September 2016 at 5 × 10 cm corms distance and planting depth of 15 cm. Measured indices included: number of flowers, fresh and dry weights of flower and stigma, number of replacement corms and total corms weight. Results showed that visual phytotoxic symptoms were not observed in pre emergence herbicides. Post emergence herbicides showed different levels of phytotoxicity from slight to severe. The application of paraquat, oxyfluorfen and oxadiazon, caused higher levels of phytotoxicity compared to other herbicides. Acetyl CoA carboxylase inhibitor herbicides caused the least injury to saffron, while acetolactate synthase inhibitor herbicides damaged saffron severely. The highest and the lowest dried stigma yield was obtained from control treatment (0.54 g.m-2) and post application of tribenuron methyl (0.003 g.m-2) respectively. Among pre emergence herbicides, the highest dried stigma yield was recorded for pendimethalin herbicide. The post application of metribuzin, oxadiazone and oxyfluorfen resulted in greater dried stigma yield than other broadleaf herbicides. By reducing herbicide dose saffron yield increased and phytotoxic levels were reduced significantly. Among the studied herbicides, trifluralin, oxyfluorfen, pendimethalin and metribuzin can be used as selected herbicides in saffron.