TWO YEARS field experiment were carried out at Demo experimental farm, Faculty of Agriculture, Fayoum University, Egypt in 2015/16 and 2016/17 seasons to examine the effect of nitrogen sources as soil application on straw and seed yields as well as seed quality of flax. A split-plot arrangement with three replications was used. Three cultivars of flax i.e., Sakha-1, Sakha-2 and Giza-9 occupied the main plots. While, N-sources, i.e., ammonium nitrate (23.5 %), urea (46.5%) and ammonium sulfate (20.6%) distributed in the sub-plot. The obtained results clarified that Sakha-1 gave the highest straw yield and its attributes mean values i.e., plant height, technical stem length and straw yield plant-1. While, Sakha-2 gave the highest mean values for number of branches plant-1 and stem diameter. In addition, Sakha-2 cultivar was exceeded the other two cultivars with regard to seed yield and related traits i.e., fruiting zone length, no. of fruiting branches plant-1, No. of capsules plant-1, 1000-seed weight and seed and oil yield fed-1. Ammonium nitrate followed by ammonium sulfate as N-sources gave the highest straw and seed yields and its related traits when compared with urea. Thus, the recommendations of this study are cultivating Sakha-2 variety and fertilized by ammonium nitrate as N-sources.
The obtained results of regression analysis of seed yield indicated that, there are two traits i.e. seed yield plant-1 and No. of capsules plant-1 in the first season and Zn mg 100g-1 in the second one, were significantly (P≤ 0.001) contributed to variation in seed yield feddan.