الفهرس 
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Abstract
This study spanned three successive seasons of 2004/2005, 2005/2006 and 2006/2007 to study the effect of biofertilizers on some diseases which infect maize and sugarbeet crops and their influence on crop yield beside product quality specially sugar, oil, flour and starch. The results included isolating, counting and assessing the ability of biofertilizers as alternatives to mineral fertilizers as well as bio-control agents against plant pathogens in
the soil under both greenhouses and the field conditions as follows:
1. In vitro studies: Counting and activities of microorganisms: 1. Total counts of bacteria:
The results clearly revealed continuous increasing in number of bacteria in both of the rhizosphere and soil of maize and sugarbeet plants taken in different growth stages per gram of dry soil and reached the highest level after 60 days sowing in maize and after 90 days in sugarbeet. It is clear that number of Bacteria in the rhizosphere is more than that in the soil indicating the effect of plant root exudates on bacteria activity. Maize plants showed rhizosphere and soil activities more than sugarbeet plants on Bacteria. The R1S ratio indicates that number of Bacteria in the rhizosphere of both crops continuously increased and reached up to more than four times over their numbers in the soil.
2. Total counts of fungi:
The results showed continuous increasing number of fungi in
both of the rhizosphere and soil of maize and sugarbeet plants taken in different growth stages per gram of dry soil and reached the highest level after 60 days sowing in maize and after 90 days in sugarbeet. It is clear that number of fungi in the rhizosphere is more than that in the soil indicating the effect of plant exudates on fungi activity. Sugarbeet plants showed rhizosphere and soil activities more than those of maize plants on increasing fungi numbers. The R/S ratio indicates that number o~ fungi in the rhizosphere of both crops reached up to five or six times more than their numbers in the soil.
3. Total counts of actinomycets:
The total numbers of actinomycetes were counted and the
results showed their continuous increasing in both of the rhizosphere and soil of maize and sugarbeet plants taken in different growth stages and reached the highest level after 15 and 60 days from sowing in maize and sugarbeet, respectively. Number of actinomycetes in the rhizosphere is more than that in the soil indicating the effect of plant root exudates on actinomycetes activities. Although maize plants showed rhizosphere activity more than sugarbeet plants, they showed less activity in the soil on increasing number of cells for this biofertilizer. agent. The R/S ratio indicates that number of actinomycetes reached five to six times
more in the rhizosphere of both crops than their numbers in the soil. 4. Total counts of Azotobacter:
Azotobacter populations in the rhizosphere and soil of maize and sugarbeet were counted and the results showed continuous increasing in their numbers in both regions and both crops that were collected in different growth stages and reached the highest level after 60 days of sowing in maize and after 90 days in sugaFbeet. It is clear that number of Azotobacter in the rhizosphere is more than that in the soil indicating the effect of plant root exudates on Azotobacter activity. Number of Azotobacter sharply decreased after 60 days of sowing maize plants indicating the effect of declining the rhizosphere activity of maize at this age on decreasing number of cells for this biofertilizer agent. There is clear stable effect of sugarbeet roots in the soil on number of Azotobacter through the period from 45 to 90 days after sowing. The R/S ratio indicates that number of Azotobacter reached more than the double in the rhizosphere of both crops than their numbers in the soil.
S. Total counts of phosphate dissolving bacteria:
The results showed that numbers of phosphate dissolver bacteria were continuously increased in both of the rhizosphere and soil of maize and sugarbeet plants with the increasing of plant growth and reached the maximum numbers after 60 days from
sowing in both of maize and sugarbeet, respectively, indicating the effect of plant exudates on number of phosphate dissolver bacteria and sugarbeet plants showed rhizosphere and soil activities more than maize plants on increasing number of cells for this biofertilizer
agent. The R/S ratio indicates that number of phosphate dissolver bacteria reached five to six times more in the rhizosphere of both crops than their numbers in the soil.
The efficiency measurement of phosphate dissolver bacteria isolates:
Two measures were done to detect the efficiency of phosphate dissolving bacteria, decreasing the pH values and increasing the sQluble \lhos\lhate in the rhizosl’here. Data determined the effect of phosphate dissolving isolates from maize rhizosphere on both pH and phosphate dissolvation from which five isolates were the best ones. Data determined the effect of phosphate dissolving isolates from sugarbeet rhizosphere on both pH and phosphate dissolvation from which eight isolates were the best ones.
Nitrogenase activity of Azotobacter isolates (!! mol C&g soiVda¥):
Data revealed the estimates of nitrogenase activity for 40 isolates of Azotobacter in the roots. Eight solates showed superiority in nitrogenase activity with values were over 70 n-moles C2HJgram soiVday. However, six isolates showed the contrary and their values
did not exceed 25 n-moles C2HJgram soil/day. The choice of Azotobacter isolates was not due to their nitrogenase activity but to their antagonistic effect as shown in the following results.
Antagonistic effect:
1. Isolates from the rhizosphere of maize plants:
The results showed that four out of forty isolates of Azotobacter showed antagonistic effect against Cephalosporium maydis the cause of late wilt in maize and two isolates attained the highest antagonistic effect against the pathogen agent represented in the spaces of 16 and 15 mm compared to the weakest isolate. The best isolates of Azotobacter which selected for inoculum preparation was isolate No. 31 for superiority in nitrogenaze activity 73.85. The results also showed that eighteen out of fifty one isolates of actinomycetes showed antagonistic effect against C. maydis the cause of late wilt in maize and four isolates attained the highest antagonistic effect against the pathogen agent represented in the spaces of 16 to 18 mm compared to the weakest isolate. The best isolate of actinomycetes that selected for inoculum is isolate No. 42 which attained the farsest space with the growth _of C. maydis. The results showed that fourteen out of fifty three isolates of phosphate dissolving bacteria showed antagonistic effect against C. maydis the cause of late wilt in maize and eight isolates attained the highest
antagonistic effect against the pathogen agent represented in the spaces of 16 and 15 to 25 mm compared to the weakest isolate. Two best isolates No. 29 of phosphate dissolving bacteria 510 ppm at 10 days were selected chosen for inoculum which attained the longest space to the growth of C. maydis with the same value of 25 millimeter affirming that phosphate dissolving bacteria had the strongest mechanism of antagonistic effect against the pathogen agent of late wilt in maize. The results showed also that phosphate dissolving bacteria genus possess chemical effect beside the antagonistic effect on fungi represented in decreasing the pH that consider as an additional preventing factor limit the growth of fungi living in the rhizosphere region of plants. The isolate of Paenobacillus polymyxa did not show any antagonistic effect against Cephalosporium maydis in maize and it only specific on root rot of sugarbeet.
2. Isolates from the rhizosphere of sugarbeet plants:
The results of antagonistic effect of Azotobacter on Fusarium oxysporium the cause of root rot disease in sugarbeet were negative affirming that Azotobacter isolates did not possess the genes response of forming the antibiotics to limit the growth of F. oxysporium hypha. However, 15 out of 43 actinomycetes isolates showed antagonistic effect against F. oxysporium in contrary to
Azotobacter isolates. The results showed that eighteen out of fifty Isolates (including Paenobacillus polymyxa) of phosphate dissolving bacteria showed antagonistic effect against F. oxysporium the cause of root rot in sugarbeet and four isolates attained the highest antagonistic effect against the pathogen agent represented in the spaces of 17 and 24 mm compared to the weakest isolates. Isolate number 6 was the best isolate of phosphate dissolving bacteria was No.6 (550 ppm) were chosen for inoculums which also attained the longest space to the growth of F. oxysporium with value of 24 mm affirming that phosphate dissolving bacteria had the strongest mechanism of antagonistic effect against the pathogen agent of root rot in sugarbeet. The results showed also that Paenobacillus polymyxa, attained a moderate antagonistic’ effect against Fusarium oxysporium the cause of root rot in sugarbeet.
2. GREENHOUSE EXPERIMENTS:
I.a. Effect of bio-fertilizing microorganisms on Cephalosporium mavdis the cause oelate wilt in maize:
Data showed the effect of biofertilization agents on decreasing the infection percentage of late wilt ill; maize plants caused by C. maydis under greenhouse cultivation and the recommended rate of mineral fertilization. It is obvious that inoculation by the actinomycetes inoculum, attained the lowest
infection percentage followed the phosphate dissolver and by the mixed inoculum inoculation by Azotobacter isolates had a little effect on the infection percentage by C. maydis compared to control with a decrease of infection %. Bio fertilizer inoculation in this case is very important because of the dual influence of decreasing infection percentage and enhancing the growth of maize plants.
I.b. The response of maize to some biofertilizers in terms of growth and N, P-uptake.
Data showed the effect of biofertilization agents on some growth and nutrient uptake characters in maize plants. The results cleared the effect of Azotobacter on increasing the succulence of maize plants appeared in fresh weight compared to control. The highest dry weight was attained by phosphate dissolving bacteria inoculation because of the effect of increasing the availability of phosphorus, the energy element in living cells. Plant height reached the highest point with Azotobacter inoculation because of the increasing of N% with this biofertilizer. Inoculation by Azotobacter enhanced of nitrogen content in plants compared to control. However, phosphate dissolving bacteria attained the highest N· uptake compared to control treatment and this result may be due to the highest dry weight resulted from the inoculation with this type of bacteria. Regarding phosphorus percentage, the phosphate dissolving
cteria attained the highest value of P% and as a result they ined the highest P-uptake compared to control.
,a. Effect of biofertilizers on Fusarium oxvsporium, the cause of root rot disease in sugarbeet:
Data discussed the effect of biofertilization agents on
ecreasing the infection percentage of root rot in sugarbeet plants ’aused by F. oxysporium. It is obvious that inoculation by mixed illoculation attained the lowest infection percentage followed by hosphate dissolving bacteria inoculation and by actinomycetes. The inoculation with mixed inoculum almost doubled the effect on
ilie causative organism of root rot in sugarbeet and resulted in aecreasing the infection percentage up to th~ half of control. Mixed inoculation in this case is very important because of the dual influence of decreasing infection percentage and enhancing the ~owth of sugarbeet root. It is clear that the high infection percentage resulted from inoculation by Paenobacillus polymyxa was less effective compared to than other bioagent.
II.b. Effect of sugarbeet to some biofertilizers in terms of growth and N, P uptake:
Azotobacter inoculation IS absent in sugarbeet because there was no antagonistic effect of it on root rot causative agent F. oxysporium. Data showed the effect of antagonistic microorganisms on some growth and nutrient uptake characters in sugarbeet plants.
II.b. The response of sugarbeet to biofertilizers in terms of growth, yield, N, P-uptake and product quality:
1. Fresh and dry weight of sugarbeet leaves:
Mixed inoculation attained the highest Fresh and dry weight of sugarbeet leaves and followed by inoculation with actinomycetes compared to control. The best level of nitrogen fertilization affected fresh and dry weight of sugarbeet leaves was attained by the second level of 75% nitrogen fertilization compared to control treatment. The highest fresh and dry weight was attained from the interaction between mixed inoculation and the second level of 75% mineral fertilization.
2. Fresh and dry weight of sugarbeet routs:
Mixed inoculation attained the highest fresh and dry weight of sugarbeet roots followed by inoculation with Paenobacillus polymyxa compared to control treatment The best level of nitrogen fertilization affected fresh and dry weight of sugarbeet roots was attained by the first level of 100% nitrogen fertilization compared to control treatment.
3. The length of sugarbeet roots:
Inoculation with Paenobacillus polymyxa attained the highest root length (cm) of sugarbeet plants followed by inoculation with mixed inoculation compared to control treatment. The best level of
nitrogen fertilization with inoculation affected length (cm) 01 sugarbeet roots was attained by the second level of 75% nitrogen fertilization compared to that attained by control treatment. The highest length (cm) of sugarbeet roots was attained from the interaction between inoculation with Paenobacillus polymyxa and the second level of75% mineral fertilization .
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4. Nitrogen uptake (g/plant) in”’sugarbeet roots:
Mixed inoculation attained the highest nitrogen uptake of sugarbeet roots and. followed by inoculation with Paenobacillus polymyxa compared to control treatment. The best level of nitrogen fertilization affected nitrogen uptake of sugarbeet roots was attained by the first level of 100% nitrogen fertilization compared to that resulted from control treatment. The highest nitrogen uptake of sugarbeet roots was attained from the interaction between mixed inoculation and the first level of 100% nitrogen fertilization.
5. Nitrogen uptake (g/plant) in sugarbeet leaves:
Inoculation with mixed inoculation attained the highest nitrogen uptake of sugarbeet leaves and followed by inoculation with Paenobacillus polymyxa compared to control treatment. The best level of nitrogen fertilization affected nitrogen uptake of sugarbeet leaves was attained by the first level of 100% nitrogen fertilization compared to that resulted from control treatment. The
’ghest nitrogen uptake in sugarbeet leaves was attained from the teraction between mixed inoculation and the second level of 75% ineral fertilization.
Phosphorus uptake (g/plant) in sugarbeet roots:
Inoculation with phosphate dissolver attained the highest osphorus content of sugarbeet roots and followed by inoculation ith mixed compared to control treatment. The best level of ’trogen fertilization affected phosphorus uptake in sugarbeet roots as attained by the first level of 100% nitrogen fertilization mpared to that resulted from control treatment.
,Phosphorus uptake (g/plant) in sugarbeet leaves:
Inoculation with mixed inoculation attained the highest osphorus uptake of sugarbeet leaves and followed by inoculation ’th phosphate dissolver or actinomycetes compared to control atment. The best level of nitrogen fertilization affected osphorus uptake of sugarbeet leaves was attained by the third se of nitrogen fertilization (50%) compared to that resulted from ntrol treatment.
The yield of sugarbeet roots (ton/feddan):
Mixed inoculation attained the highest yield of sugarbeet 18 and followed by inoculation with Paenobacillus polymyxa mpared to control treatment. The best level of nitrogen
fertilization affected yield of sugarbeet roots was attained by the full level of 100% nitrogen fertilization compared to that resulted from control treatment.
9. Sucrose percentage in sugarbeet roots:
Inoculation with phosphate dissolver attained the highest sucrose percentage of sugarbeet roots followed by inoculation with mixed inoculum compared to control treatment. The best level of nitrogen fertilization affected sucrose percentage of sugarbeet roots was attained by the third rate of nitrogen fertilization of 50% compared to that resurted from control treatment.
10. Sugar yield of sugarbeet crop:
Inoculation with mixed or phosphate dissolver inoculum attained the highest sugar yield of sugarbeet compared to control. The best level of nitrogen fertilization affected sugar yield of sugarbeet roots was attained by the second rate of 75% nitrogen fertilization compared to that resulted from control treatment.
III. Nitrogen and Phosphorus content (PPM) in the soil at the end of field experiments:
1. Nitrogen content in the soil (ppm):
Mixed inoculation attained the highest nitrogen content (ppm) in the soil followed by inoculation with Paenobacillus polymyxa compared to control treatment. The best level of nitrogen
ilization affected nitrogen content (ppm) in the soil was attained the full dose of nitrogen fertilization compared to that resulted m control treatment. The highest nitrogen content (ppm) in the 11 was attained from the interaction between mixed inoculation d the full dose of mineral fertilization.
Phosphorus content in the soil ppm:
Mixed inoculation attained the highest phosphorus content pm) in the soil followed by inoculation with phosphate dissolver mpared to control treatment. The best level of nitrogen rtilization affected phosphorus content (ppm) in the soil was
ined by the first level 100% of nitrogen fertilization compared to t resulted from control treatment.
The author is to recommend usmg biofertilizer agents as ffective alternatives to those of mineral fertilizers or m n mbinations with lower levels of them in order to protect the
nvironment from pollution and also protect plants from diseases at specially from those latent in the soil.