Two field experiments were carried out at Sakha Agricultural
Research Station, Kafer El-Sheikh Governorate, Egypt during the two
successive seasons of 2006/2007 and 2007/2008.
These experiments were performed to study the effect of
biofertilization with some nitrogen fixing bacteria, Azotobacter
chrococcum, Bacillus polymyx and either in individual form or in
mixture of them. or Azospirillum brasilense this inoculation was
performed under different levels of N-fertilizer, 25%, 50% and 100%
of the recommended dose as well as their interaction on sugar beet
plants. obtained results proved that:
Application of N-mineral fertilizer led to significant increases
in root dimensions (root length and diameter), tops and root yield,
sucrose % of juice and sugar yield. Where using of 80 Kg N/fed
raised the values of tops yield by 19.17 and 5.64 % in the 1st season
corresponding by 8.64 and 11.62 % in the 2nd season compared with
20 and 40 Kg/N /fed. However, this root yield amounted by 47.8%
and 23.9 % in the 1st season corresponding by 36.69% and 17.48 % in
the 2nd season. Purity (%) of sugar beet root juice was insignificantly
affected by the used N-level.
Obtained results also revealed that use of these bacteria gave
significant increases in root dimensions including root length and
diameter, TSS (%), sucrose %and purity of juice, tops and root and
sugar yield. Generally, the mixture of three used bacteria gave the best
results of all parameters under study. The highest values of top and
root yield by bacterial mixture treatment were 15.87&37.8 tons/fed in
the1st and 2nd
respectively
season compared with 11.24 and 20.8 tons/fed,
Regarding the interaction effect between the two examined
factors N2-fixing bacteria and N-mineral fertilizer on sugar beet yield
and yield components. Data pointed out that this interaction caused
significant response of root dimensions, where the bacterial mixture
with 80 kg N/fed produced the maximum values of root length and
diameter which represented 26.48 and 25.40 cm of length and 16.77
and 15.93 cm of diameter in the 1st and 2nd season, respectively. It
could be remarked that the most effective treatment on purity (%) and
sugar yield was the combination between the three bacterial strain
with 80 kg/N/fed.