الفهرس 
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Abstract
Application of biofertilizers in order to improve the
growth and production of Black cumin (Nigella sativa) was
conducted in this work. Two field experiments were carried out
in El-Sheikh Zowayed North Sinai governorate, Egypt during the
two successive seasons 200112002 and 200212003 to study the
effect of using biofertilizers on the productivity of black cumin
(Nigella sativa) and investigating the obtained seeds against
some pathogens.
The soil was amended with compost at the rate of 15 m 3/
feddan in the field experiment. It was supplemented with the
recommended doses of Supper phosphate (P205 15.5%)
l50Kg/Feddan and potassium sulfate 48% (l00 kg/feddan).The
experiment included 4 types of treatments namely uninoculated
and inoculated treatments with Azotobacter chroococcum and
Bacillus megaterium alone or mixed. Each set of treatments
contained three levels of mineral nitrogen fertilization; zero, 25
and 50 Kg /feddan under drip or rain irrigation. The used
bacterial strains were prepared in microbiology lab of Desert
Research Center. The soil and plant sampling to determine
microbiological and chemical analyses were obtained at three
stages of growth namely 60,150 and 210 days after planting.
The efficiency of antimicrobial activities of oil content of each
treatment against some pathogenic microorganisms was
determined.
SUMMARY
The obtained results can be summarized as follows
1- Generally total microbial counts, densities of Azotobacter and
densities of Bacillus megaterium under drip or rain irrigation
increased at 60, 150 days and then decreased at 210 days. Also
the increasing of the rates of mineral nitrogenous fertilization at
25and 50 Kg N/fed. with inoculation by azotobacters caused
increment in the total number of microbial count, Azotobacter
and Bacillus megaterium counts as compared with uninoculated
treatments at 60 and 150 days.
2- Inoculation with Azotobacter chroococcum alone or mixed
with Bacillus megaterium under drip irrigation in the presence of
25 Kg N/feddan gave the highest dehydrogenase activities. The
rate of metabolic activity in soils under investigation show that
all soil conditioning treatments achieved higher dehydrogenase
activities than untreated samples in both seasons.
3- Organic carbon in the soil that was planted with Nigella sativa
as affected by biofertilizer continuously decreased in the organic
carbon content in all treatments as well as untreated soil up to the
end of the experiment.
4- The increasing of mineral nitrogenous fertilization rates with
inoculation by Azotobacter chroococcum alone or mixed with
Bacillus megaterium under drip or rain irrigation resulted in a
significant gradual increase in soil nitrogen content after 60 days
from plant age as compared with the same mineral nitrogenous
fertilization rates in case of absence of inoculation with
Azotobacter chroococcum alone or mixed with Bacillus
megaterium.
5-Inoculation of the soil with Azotobacter chroococcum and or
Bacillus megaterium under drip or rain irrigation resulted in
significant increases of available phosphorus or potassium after
60 days from planting as compared with uninoculated
treatments.
6- Increasing of plant age caused an increase of plant heights in
general. Increasing of mineral nitrogenous fertilization rates
accompanied by dual inoculation with Azotobacter chroococcum
and Bacillus megaterium under drip irrigation had a significant
effect on increasing plant heights in comparison with
uninoculated treatments.
7- The number of branches was increased with using half or full
dose of mineral nitrogenous fertilization in the presence of dual
inoculation under drip irrigation than individual inoculation or
uninoculated treatments. There was not any increment in the
number of branches with proceeding age of plant from 150 days.
8- By increasing age of plant, an increment in the fresh and dry
weights of the plants was occurred till 210 days. Dual
inoculation with Azotobacter chroococcum and Bacillus
megaterium under drip irrigation resulted in a great increment in
the fresh and dry weights than the uninoculated treatments or the
individual inoculation especially at 50 Kg N/feddan,
9- The results indicate that the organic carbon in N sativa plants
or seeds significantly increased by dual inoculation with
Azotobacter chroococcum and Bacillus megaterium as well as by
increasing inorganic N-fertilizer levels up to 50 Kg Ifeddan
under drip or rain irrigation.
10- A significant increase in the total nitrogen content in N
sativa plants has been occurred at 60 and 150 days of plant age
while general decrease in total nitrogen exhibited at 210 days.
Inoculation by Azotobacter chroococcum and lor Bacillus
megaterium under drip or rain irrigation with increasing of
mineral nitrogenous fertilization rates caused a general increase
in the total nitrogen contents in the plants.
11- Total phosphorus or potassium of N sativa plants showed
similar trend, as the phosphorus and potassium increased up to
150 days then decreased at 210 days. Inoculation with
Azotobacter alone or mixed with Bacillus megaterium under
irrigation caused highly significant increases for all treatments as
compared with uninoculated ones.
12- Dual inoculation with Azotobacter chroococcum and
Bacillus megaterium and amended with half or full dose ofNfertilizer
under drip irrigation caused a significant increase in the
total nitrogen content of seeds. The increment was higher than
those which resulted from mineral fertilization only.
13- The same trend of total nitrogen content was also noticed for
total phosphorus or potassium in seeds of Nsativa which
increased with dual inoculation with Azotobacter and Bacillus
megaterium under drip irrigation when using half or full dose of
N-fertilizer caused the highest values comparing with
uninoculated treatments.
14- Inoculation with Azotobacter chroococcum and Bacillus
megaterium as solely or mixed inoculation under drip irrigation
in the presence of 50 Kg N/feddan gave the highest yield of N.
sativa seeds or oil yield in comparison with uninoculated
treatments or rain irrigation.
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15- The inhibitory effects of black cumin essential oil were
studied against three groups of test microorganisms. The highest
inhibition zones were observed by oils obtained by using dual
inoculation in the presence of half dose of inorganic N-fertilizer
when it was used against some food-borne pathogens,
phytopathogenic bacteria or phytopathogenic fungi.
16- The obtained oil when using dual inoculation exhibited
decreases in the minimum inhibitory concentration (MIC) for all
test microorganisms especially when amended with half or full
doses ofN-fertilizer.