Abstract
In Algeria, weeds are a formidable problem for cereal crops grown in conventional planting methods and in a semi-arid climate. During the 2015/2016 crop cycle an experiment was carried out in the Khenchela region, in two cereal fields, during a period from the full tillering stage until the end of the stem elongation, in order to know the diversity and spatial-temporal dynamics of the weed flora associated with the crops. The fields contained the soft wheat (Triticum aestivum L.) HD1220 variety, and barley (Hordeum vulgare L.), El-Fouara variety and the temporal dynamics of the weed flora associated with these crops was studied. A quadrat was used to sample the weeds. Seven weed species were identified, belonging to five orders and five botanical families, with a total of 1258 individuals. Both fields were infested with the same weed species. The species Sinapis arvensis (18.5%) was the most frequent in the wheat field, while Carduus pycnocephalus (17.4%) was the most dominant in the barley field. The relative abundance (RA%) values of the species surveyed were higher in the stem elongation stage than in the tillering stage. The Shannon index (H') value did not exceed 2.8 bits, and the equitability (E) was 0.98, which shows a balance in the floristic stands. ANOVA comparison between the two crops, wheat and barley, for the phenological stages of the host plant showed significant to very highly significant results for weed species at the tillering stage. In contrast, during the stem elongation stage, wheat maintained the significant results noted during the tillering stage, while barley showed no significant results.