A field experiment was conducted at the Experimental farm, College of agriculture- University of Kirkuk during the winter season (2019-2020) with the aim of studying Heat accumulation and its relationship to the pattern and capacity tilling of fifteen of soft wheat cultivars, which is (Tamoz1 ،Ariz ،Api99 ،Salaimania2 ،Feahth ،Florika ،Klaik ،Kawiz ،Babel ،Sham4 ،Sham6 ،
Abo Graip2 ،Birea ،Alofia ،Gehan). The seeds were planted on (11/24/2019), and the Randomized Complete Block Design (RCBD) with three replicates. Each repeater included 15 experimental units containing three lines of distance between them 25 cm and the length of the line 4 m. The varieties were randomly distributed and the seeds were planted on A distance of 5 cm between one plant and another, at the rate of one grain in the place of cultivation, in order to give the area to grow plants freely enough to ensure the maximum in the formation of tillers. The results showed: All wheat cultivars followed a similar behavior in pattern of tillers production, but they differed in reaching the maximum number of tillers. The Feahth variety excelled in giving the highest number of tillers (10.8) tiller/plant. While the Birea cultivar excels in giving the highest cereal yield (3558.4) kg.ha-1. Plants needed to enter the startup
phase tillers to heat accumulation of 223.6 °C. While Plants of all various kinds entered the stage of the maximum number of tillers- plant when they possessed a heat accumulation of (527.6 °C), which represents approximately more than quartier of the total heat accumulation during the growing season which reached 2074 °C. The best stage in the quotient is the first stage and indicates the early stage in giving tillers and the last stage. The cultivars showed four groups according to the cluster analysis and the basic components analysis, which gives an indication to the plant breeders to choose the different parents when hybridization.