This investigation was conducted during the two successive winter seasons of 2008/ 2009 and 2009 / 2010 at Private Farm, El-Baalwa Zone, Ismaelia Governorate to study the performance of onion cv. Giza 20 to chicken manure, biofertilizers, i.e. nitrobein and phosphorein ,as well as, biostimulant, i.e. yeast each alone or mixed and NPK chemical fertilizers at the recommended dose as a control treatment on growth, chemical composition of plant, yield and its components ,as well as, the nutritive value of onion bulb.
Obtained results could be summarized as follows: Applying chicken manure followed by nitrobein, phosphorein and yeast or nitrobein and phosphorein only were the most effective treatments compared to NPK mineral fertilizers at the recommended dose. Also, these applications resulted in the highest values of plant height, number of leaves, neck and bulb diameter and dry weight of roots, leaves, bulb and total plant, minerals concentration (N, P and K % in plant), bulb yield and its components (bulb diameter, bulb fresh weight , marketable and total yield per feddan), as well as, the nutritive value of bulb (TSS, N, P and K percentage and total protein).Meanwhile, the yield of culls was decreased. Generally ,applying transplants with chicken manure or treated onion transplants with mixture of nitrobein , phosphorein and yeast may be advisable to obtain the best growth and yield compared to using chemical fertilizers.