Detection of New Strains of Echinochloa Crus-Galli Resistant to ALS-AHAS and Accase Weedicides for the First Time in Iraq

Abstract

The competition between weeds and rice crop is one of the most important restrictions that limit the success of production in the world. Despite the excessive and multiple use of herbicides, weeds still one of the biggest problems that facing rice cultivation in Iraq, as both farmers, and agricultural departments complained about the challenges of controlling it particularly the herbicide-resistant strains.  Current study aimed to determine the reason/s for the spread of the barnyard grass and its resistance to ALS-AHAS and ACCase herbicides. A field survey was conducted in different areas of Najaf province where rice crop is cultivated. Weeds samples were collected and diagnosed phenotypically and molecularly. The outcomes of this research showed that the geographical distribution of weeds accompanying the rice crop indicated that the highest average numerical density of the spread of weeds is 43% in the Shallal- Al-Mishkhab area, and the barnyard grass weed was occupied about 36% of the percentage of weeds in the areas included in the field survey. Phenotypic diagnosis of Echinochloa crus-galli samples also revealed the presence of the variety (var. crus-galli) for the first time in Iraq, supported by molecular diagnosis that resulted in the registration of 19 new strains that were deposited at NCBI under the serial number (OQ591719 to OQ591737) for the first time in Iraq. The phenotypic characteristics of the seeds showed that their average size was 2.82 - 3.67 mm and their average weight was 0.0012 - 0.0038 g. Anatomical characteristics showed that the average thickness of the upper epidermis of the cochineal was 146.22 µM, the lower one was 181.76 µM, and the thickness of the shell was 136.48 µM, which indicates the great ability of seeds to spread and sustain growth. The phylogenetic tree the registered strains showed a genetic affinity with the barnyard grass strains registered in the NCBI database that distinguish by its resistance to herbicides.