THE FIELD work was carried out at the experimental farm "Demo" in faculty of Agriculture, Fayoum University, during two successive seasons of 2013/2014 and 2014/2015. The aim was to investigate the effect of foliar, ground application (soil drenching) and both the two methods using (0, 5, 10 and 15g/l) of bio-fertilization with yeast (Saccharomyces cerevisiae) on the growth, yield and chemical constituents of Fenugreek plants. The results assured that Fenugreek plants highly reacted positively and significantly to different methods of bio-fertilization with active dry yeast either by spraying or soil drenching or using both together. Using the highest concentrations (10 and 15 g/l) of yeast by spraying or soil drenching, as individually, or applying them together as interaction proved to have the leadership in enhancing and increasing all vegetative growth characters, plant height, branches number plant-1, fresh and dry weight plant-1, seed yield and its contents of mucilage (%), trigonelline, protein and chemical composition of Fenugreek plants, chlorophyll a, b, carotenoids, contents and total carbohydrates content.
Fenugreek plants should be sprayed and drenched at a concentration of 10 and 15 g/l of yeast. Moreover, active dry yeast should be more mechanized and used in agriculture as a harmless bio-fertilizer with a marvellous ability in increasing seed yield and chemical constituents.