The experiment commenced in the crop season of 2021–2022 at two experimental locations—first at the Department of Field Crops, College of Agriculture and Forestry, University of Mosul, Iraq, and the second was at a farmer’s field in Dohuk Governorate, Iraq. The presented study assessed the two wheat cultivars (Rasheed and Buhouth1) and their response to different concentrations of bread yeast (0, 4, and 8 g L^-1), as the wheat plants incurred spraying with yeast powder. The experimental layout used the randomized complete block design (RCBD) with three replications. According to the results, cultivar Rasheed showed significant superiority for plant height (49.4 and 50.2 cm), spike length (6.9 and 7.3 cm), and spikes plant^-1 (5.7 and 6.1 spikes plant^-1), and Buhouth1 cultivar was substantially superior for grain yield (18.6 and 20.6 g plant^-1) and harvest index (34.77% and 40.26%) for both locations. Also, from the results, the time of adding bread yeast in the booting stage was superior for characteristics: spikes plant^-1 (5.9 and 5.7), grain yield (19.1 and 20.9 g plant^-1), and harvest index (34.85% and 40.42%), whereas the time of addition in the tillering stage was superior for the 1000-grain weight (36.97 and 36.66 g) and biological yield (58.4 and 56.0 g) for both locations. The bread yeast concentration findings revealed a considerable advantage of the concentrations at 4 and 8 g L^-1 (they did not differ significantly from one other) over the absence of bread yeast concentration of 0 g L^-1 in the tillers plant^-1, spike length, spikes plant^-1, and biological yield. In the harvest index %, the concentration above 4 g L^-1 was best for the two locations. Most binary and triple interactions of the components in this investigation revealed substantial changes, particularly when their part involved spraying with bread yeast for the two experimental locations.

Keywords: Wheat (Triticum aestivum L.), yield-related traits, environmental locations, Saccharomyces cerevisiae, yeast

Key findings: Cultivar Rasheed showed significant superiority for plant height, spike length, and spikes plant^-1, while Buhouth1 cultivar superiority was in grain yield and harvest index for both locations. On adding time of bread yeast, the time of addition in the booting stage was superior in the characteristics of spikes plant^-1, grain yield, and harvest index, whereas the time of addition in the tillering stage was superior in the characteristics of 1000-grain weight, biological yield, and the conc. of 4 and 8 g L^-1 compared with 0 g L^-1.