Two field experiments were conducted during the two successive winter
seasons of 1 ~99/2000 and 2000/2001 to evaluated the effect of three commercial
biofertilizers: microbein(a mixture of Azotobacter. Azospirillum . Pseudomonas ,
Rhizobium and Bacillus). Rhizobacterin ( a mixture of Azotobacter and Azospirillum)
and Halex-2 (a mixture of Azotobacter, Azospiillum and Kebsiella) with different
nitrogen fertilizer levels (0.18,36,54.72 and 90 kg N fed:') on bulbs yield 0 f 0 nion
(Allium cepa L.) cv. giza 20 and its component ( total bulb yield ton fed", marketable
bulb weight (g), Average bulb weight (g), and average bulb diameter (cm). Generally, addition of 72 kg N fed:' combined wtth Halex-2 biofertilizer was
sufficient and adequate to produce maximum and economic yield in both seasons.
Four polynomial quadratic equations were established to express the response of
onion bulbs yield to N fertilization and biofertilizers inoculation. The experimental yield
values and the corresponding calculated values were not significantly different as
tested by the standard error of estimates SE and high values of correlation coefficient
(R). N_oPI. 'and corresponding YOP'. were calculated for both years and the data revealed
that the N fertilization application was more profitable when applied to onion seedlings
with the biofertilizer Halex-2 as indicated by highest values of net returns compared
with the other treatment combinations.