This study was conducted at the experimental Farm of the Faculty of Agriculture Moshtohor , Quliubia governorate during the winter seasons of 2013/2014 and 2014/2015 to investigate the effect of nitrogen fertilizer at the rate of 0,25,50 and 75 kg N/fed. and spraying the plants with salicylic acid at 1g/l ,amino acids at 0.5ml/l and seaweed extract at 5ml/l and biogen bio fertilizer as a soil addition at 800 g/fed as well as their combinations in addition to the control treatment on flowering behavior ,seed yield and its quality of spinach plant ,cv. Saloniki. Obtained results showed that increasing nitrogen levels up to the highest used levels ( 50 or 75 kgN/fed) reflected the highest values of number of female plants ,sex ratio (M/F) , produced seed yield either per plants ,or feddan ,seed index(weight of 100 seeds) ,germination percentage and germination rate . In addition, treating the plants two times during the growing season with all tested growth stimulants enhanced positively the number of female plants and sex ratio towards femalenss and improved the produced seed yield and its quality (seed index, germination percentage and germination rate.) In this connection, treating the plants with biogen as a soil addition was the best treatment in this concept. Therefore, it could be recommended to add nitrogen fertilizer at 50 or 75 kg N/fed combined with soil addition of biogen at 800g/fed to get the highest seed yield with best quality.