Changes in the weed flora of cotton fields in the Eastern Mediterranean region of Turkiye

Cotton is the most dominant field crop, especially in higher soil saline parts of the Eastern Mediterranean region of Türkiye. This study aims to determine the current statues of weed flora of cotton fields in the East Mediterranean region, to compare it with weed flora in 1991-1992 and to understand whether a weed flora shift has occurred in these fields. Eighty-two cotton fields were surveyed during the growing season (July and August) in 2018, and thirty-seven weed species distributed in 17 families were found in the survey fields, where 18, 23, 17, and 33 of them were recorded in the Kahramanmaraş, Hatay, Mersin, and Adana provinces, respectively. Canonical correspondence analysis revealed that the phytosociological composition of the cotton fields was significantly related to the P content of the soil, average temperature, and cumulative rainfall. The current weed survey also indicated that these fields were under the threat of some invasive alien plant species that had not been found in previous surveys, such as Ipomoea triloba L., Amaranthus palmeri L., and Cucumis melo var. agrestis Naudin. Although cotton fields in the region were reduced by two-thirds in 2018 compared to 1991-1992, weed richness increased. Weed flora shifts were influenced by crop, crop rotation, herbicide use, irrigation, and landscape factors of cotton fields in the East Mediterranean Region of Türkiye.