Effect of Brassinolide Levels on Some Growth of Sunflower Hellanthus annuus L

Field experiment was carried out at Research Station, College of Agriculture, Anbar University, during 2019 spring season to study the effect of four level of brassinolide (0, 0.5, 1, 1.5 mg L-1) on some Morphological characters of three sunflower varieties (Ishaqi 1, Akmar and Sakha) The results of the statistical analysis showed the significant effect of the cultivars and brassinolide concentrations on the studied characters. The sprayed plants with 1.5 mg L −1 of brassinolide recorded the highest values of plant height (197.5 cm), leaf area (6179 cm 2 . plant 1 ), mean of dry weight (171.5 g plant 1 ), Crop Growth Rate (17.709 gm. m −2 . days −1 ) and Net Assimilation Rate (1.47 gm −2 . day −1 ). Whereas the cultivars differed significantly in all the studied traits, as Sakha variety recorded the highest values for plant height, leaf area, mean of the dry weight to plant, Crop Growth Rate and Net Assimilation Rate, (182.2 cm, 7738 cm 2 .plant −1 , 212.6 g. plant 1 , and 13.317 gm .m −2 . days 1 , and 1.96 gm −2 .day 1 ) respectively.