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Fayez, M., S. H. Shehata Heba, G. A. El-Morsy, A. Rahal, and A. F. Shahaby, "Complement of integrated fertilizer management and integrated pest management concepts to ameliorate faba bean growth and yield", Archives of Agronomy and Soil Science, vol. 50, issue 4-5, pp. 397 - 419, 2004. AbstractWebsite

Twenty-one microbial preparations recommended for controlling pathogenic fungal strains causing root rot and wilt diseases of faba bean were investigated for antibiosis against several symbiotic and associative diazotrophs adopting a modified agar-plate-inhibition-zone assay. Rhizobium and Bradyrhizobium exhibited a somewhat similar susceptibility to biocontrol agents while associative diazotrophs showed variable responses. Azotobacter, compared to others, was severely inhibited by such bio-candidates. The members of the biofertilizer formulation ‘Biofertan’ did bear mixed cultivation with the majority of biocontrol agents. Among those, Bacillus subtilis was deemed the pioneer. In pot experiments, almost all the antagonists significantly restricted the severity of root rot and wilt diseases besides modifying faba bean seedling stand and improving plant development. This was very obvious with shoot biomass increases of >50%. Moreover, the bioagents successfully recovered the legume establishment, seriously injured due to pathogenic fungal infection. Simultaneous inoculation with Rhizobium and biocontrol agents provided more growth stimulation compared to either when introduced individually. Field-grown faba beans were inoculated with the diazotroph and representatives of biocontrol strains by two different methods, seed coating and over-head soil. Growth parameters determined were the highest when the legume plant was seed-coated by Rhizobium simultaneously over-head soil inoculated with the bacterial bioagents; this was reported with Bacillus subtilis and Pseudomonas aerugenosa. The significance of combined application of biofertilizer and bioagent to ensure cheap, clean and safe farm products is discussed. © 2004 Taylor & Francis Ltd.

Youssef, H. H., M. Fayez, M. Monib, and N. Hegazi, "Gluconacetobacter diazotrophicus: A natural endophytic diazotroph of Nile Delta sugarcane capable of establishing an endophytic association with wheat", Biology and Fertility of Soils, vol. 39, issue 6, pp. 391 - 397, 2004. AbstractWebsite

Gluconacetobacter- like diazotrophs were encountered as dense populations inside the root and stem tissues of sugarcane cultivated in ancient agricultural fields of the Nile Delta. Counts of >105 cells g-1 were recorded in root and stem samples. The leaves contained a smaller population (<103 g-1). The typical dark-orange colonies which developed on LGIP agar plates were purified. Identification was performed with the API microtube systems: API 20E for Enterobacteriaceae and API 20NE for non-Enterobacteriaceae. API profiles of the local isolates were closely related to those of the type culture Gluconacetobacter diazotrophicus (ATTC 49037). The isolates successfully reduced C2H2 and produced appreciable amounts of ethylene in the presence of cane juice. This suggested that the local isolates are closely related to the type strain G. diazotrophicus. Wheat seedlings were inoculated with a number of isolates under gnotobiotic conditions. Both optical and scanning electron microscopy showed that endophytic Gluconacetobacter spp. were present in all the samples tested. They were observed in apparently intact and enlarged epidermal root cells, and also in stem tissues, indicating that the bacterium was able to migrate upward into the shoot tissues. Although Gluconacetobacter inoculation did not stimulate the growth of the cereal plant, the results obtained are particularly interesting because this bacterial species was capable of colonizing the internal tissues of wheat, not considered a natural host until now. © Springer-Verlag 2004.

Othman, A. A., W. M. Amer, M. Fayez, and N. A. Hegazi, "Rhizosheath of sinai desert plants is a potential repository for associative diazotrophs", Microbiological Research, vol. 159, issue 3, pp. 285 - 293, 2004. AbstractWebsite

Among 42 plant species representing the flora of north Sinai, two possessed sand grain sheath encasing the roots. They are Panicum turgidum Forssk. and Stipagrostis scoparia (Trin.and Rupr.) deWinter. Rhizosheaths, compared to surrounding free sand, accommodated higher population density of microorganisms including associative diazotrophs. Isolates secured belonged to the species of Bacillus circulans, Paenib. macerans (Bacillus macerans), Enterobacter agglomerans, Agrobacterium radiobacter and Chryseomonas luteola (Pseudomonos luteola). The rhizosheath potentiality in re-vegetating sand dunes and arid lands, through nitrogen fixation, plant-water relationship and root continuity for nutrient uptake, are discussed. © 2004 Elsevier GmbH. All rights reserved.

Hegazi, N. A., and M. Fayez, "Biodiversity and endophytic nature of diazotrophs other than rhizobia associated to non-leguminous plants of semi-arid environments", Archives of Agronomy and Soil Science, vol. 49, issue 2, pp. 213 - 235, 2003. AbstractWebsite
Othman, A. A., W. M. Amer, M. Fayez, M. Monib, and N. A. Hegazi, "Biodiversity of diazotrophs associated to the plant cover of north sinai deserts: Biodiversität diazotropher assoziiert mit der pflanendecke der wüsten nordsinais", Archives of Agronomy and Soil Science, vol. 49, issue 6, pp. 683 - 705, 2003. AbstractWebsite

Efforts are made to record biodiversity of microflora and diazotrophs associated with the plant cover of the major agricultural development areas in north Sinai, around the El-Salam canal, a newly-constructed canal that brings Nile water westward across the Suez canal. Natural plant communities were collected from three major areas. Ectorhizosphere, endorhizosphere and phyllosphere samples were examined for total microbial population and diazotrophs. The vegetation of South Qantara (area I) is characterized by the dominance of Stipagrostis scoparia followed by Nitraria retusa, Convolvulus lanatus, Cornulaca monacantha and Filago desertorum. Rabaa-Bir El Abd (area II) is dominated by Artemisia monosperma, Panicum turgidum and Zygophyllum album. Euphorbia terracina, Oligomeris linifolia, Astragalus kahiricus, Hyoscyamus muticus and Thymelea hirsuta represent the major plants of El Ser and Al Quarir (area III). Microorganisms colonized root surfaces of all tested plants ranging from > 10 5 to 10 10 cfu g − 1 . Diazotrophs were common residents (10 10 cfu g − 1 ), invaded the root tissue and established endophytically (10 2 – 10 6 cfu g − 1 ). Fifty-one N 2 -fixing isolates were obtained. Among the 32 bacilli isolates, Bacillus polymyxa and Bacillus circulans were more common compared to Bacillus macerans. BNF Gram-negative isolates belonged to Enterobacter agglomerans, Enterobacter gergoviae, Enterobacter amnigenus, Klebsiella pneumoniae, Pseudomonas luteola, Pseudomonas cepacia, Agrobacterium radiobacter and Azospirillum spp. © 2003, Taylor & Francis Group, LLC.

Othman, A., M. E. Shawky, W. M. Amer, M. Fayez, M. Monib, and N. A. Hegazi, "Biodiversity of microorganisms in semi-arid soils of north sinai deserts", Archives of Agronomy and Soil Science, vol. 49, issue 3, pp. 241 - 260, 2003. AbstractWebsite

North Sinai environment is currently subjected to changes due to the major agricultural development project of El-Salam canal which brings Nile water to the arid deserts of Sinai. Therefore, intensive efforts are made to record biodiversity of natural microflora and diazotrophs associated to the plant-soil system of the major agricultural development areas around the canal. Fourteen soil profiles were made, during the seasons 1997-2000, representing major sites of the area investigated (South Qantara, Rabaa-Bir El-Abd and El-Ser and Al-Quarir). Physico-chemical and microbiological properties of soils tested are presented. Microbiological profiling included total population of Gram positive and Gram negative bacteria, sporeformers, thermophiles, diazotrophs and spore-forming diazotrophs. Results obtained are discussed to relate physico-chemical properties to soil biofertility in an effort to categorize general fertility levels of soils under investigation. © 2003, Taylor & Francis Group, LLC.

Hegazi, N. A., and M. Fayez, "Biological nitrogen fixation to maximize productivity of intercropped legumes and non-legumes: Ten years of field experimentations in semi-arid deserts of Egypt", Archives of Agronomy and Soil Science, vol. 47, issue 1-2, pp. 103 - 131, 2001. AbstractWebsite

A number of field trials was executed in semi-arid deserts of Ismailia, Egypt, to experiment growth and productivity of sole or mixed canopies of legumes (soybean, leucaena, sesbania, berseem and grasspea) and non-legumes (corn, Rhodes grass, elephant grass, ryegrass and barley) when inoculated with N 2 -fixing bacteria (diazotrophs) in presence or absence of N fertilizers. An average estimate of > 20 Kg N acre −1 was transferred to neighbouring unfertilized corn, and land equivalent ratio (LER) reached 1.35. Rhodes grass mixed with sesbania or leucaena produced higher biomass yield compared to pure N-fertilized stands; increases of 66–91% and 22–29% were reported for inoculated and non-inoculated plants respectively. In mixed canopy with berseem, dry matter yield of the non-legume partner increased compared to that in pure stands, being higher for barley (120–255%) compared to ryegrass (62–115%). Similar trends were scored with N yield. Response of elephant grass to inoculation with associative diazotrophs was more pronounced when intercropped with leucaena as increases over pure stand in dry matter production approximated 40%. On the other hand, both grasspea and barley were negatively affected by intercropping. Total biomass and N-yields of barley were more affected than grasspea. © 2001 Taylor & Francis Group, LLC.

Abbas, M., M. Monib, A. Rammah, M. Fayez, and N. Hegazi, "Intercropping of sesbania (sesbania sesban) and leucaena (leucaena leucocephala) with five annual grasses under semi-arid conditions as affected by inoculation with specific rhizobia and associative diazotrophs", Agronomie, vol. 21, issue 6-7, pp. 517 - 525, 2001. AbstractWebsite

Intercropping of legumes and non-legumes is considered to improve the quality and quantity of field forage crops. Under semi-arid desert conditions, intercropping of leucaena and sesbania with some annual grasses (barley, pearl millet, and Rhodes-, ryeand sudan-grasses) was evaluated in a series of field trials. Inocula of specific rhizobia for legumes and a composite of associative diazotrophs for non-legumes were applied in the presence or absence of N fertilizers. Rhizobia inoculation was indispensable, and supported better growth of legumes which extended to the neighboring non-legumes. Associative diazotrophs improved biomass and N yields of non-legumes, particularly in the presence of moderate N fertilization for winter barley and rye grass and of higher doses of 300 kg N·ha-1 for summer pearl millet and sudan grass. Intercropping improved productivity of non-legumes, in particular barley mixed with sesbania, and the calculated N-transfer from legumes to non-legumes ranged from 20 to 70 kg N·ha-1.

Fayez, M., and Z. Y. Daw, "Growth and acetylene reducing activity of azospirilla as affected by interaction with soil streptomyces, penicillia and fusaria", Soil Biology and Biochemistry, vol. 22, issue 8, pp. 1143 - 1149, 1990. AbstractWebsite

A total of 68 actinomycete and 63 fungal isolates obtained from various soils were tested for their ability to antagonize different strains of Azospirillum in sterile soil. It was found that between 78 and 87% of the streptomycete and between 75 and 83% of the fungal isolates respectively did not inhibit azospirilla. Numbers of azospirilla in soil were seriously reduced when they interacted with some of the streptomycete and fungal isolates. In soil treated with both azospirilla and either streptomycetes or fungi, the nitrogenase activity ranged from ca 2-210 nmol C2H4g-1h-1. In general, the acetylene reducing activity (ARA) in soils treated with fungi was reduced more seriously than those treated with streptomycetes; the mean ARA reported in the presence of fungi was 23 nmol C2H4g-1 h-1 against 48 in the presence of streptomycetes. The reduction in both azospirilla number and ARA in soil may have reflected the increasing population of antagonists. Highly-significant negative correlations between the diameter of inhibition zones produced by the active Streptomyces and fungal isolates using the agar-disc method were found with both numbers and ARA of most Azospirillum strains in soil. © 1990.

Fayez, M., "Interactions of some nematicides with Azospirillum lipoferum and the growth of Zea maize", Zeitschrift für Pflanzenernährung und Bodenkunde, vol. 153, issue 4, pp. 219 - 223, 1990. AbstractWebsite

The possible interaction of four nematicides (Terbufos, Carbofuran, Fenamiphos, and Aldicarb) with Azospirillum lipoferum and growth of two Zea maize cultivars was studied in a greenhouse experiment. Application of nematicides, Fenamiphos in particular, resulted in higher plant length, dry matter production and N yield over the nematicide‐untreated plants. Azospirillum spp. inoculation stimulated the growth of nematicide‐treated Z. maize. Among the nematicides used, Carbofuran and Aldicarb inhibited the nitrogenase activity on plant roots more seriously than Fenamiphos and Terbufos. Generally, the inhibition percentages in acetylene reducing activity in soil of inoculated treatments were lower (14.4 ‐ 61.8%) than those reported for the uninoculated ones (21.4 ‐ 73.9%). Soil, irrespective of treatment, regained a part of its normal N2‐ase activity with time. Field concentrations of all nematicides showed different inhibitory effects on N2‐ase activity of Azospirillum spp. in culture medium, such effects increased with increased doses (10‐ and 100‐ fold) and incubation periods (10 days). The contribution of Azospirillum spp. to the N economy of soil treated with nematicides is discussed. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

Fayez, M., "Untraditional N2-fixing bacteria as biofertilizers for wheat and barley", Folia Microbiologica, vol. 35, issue 3, pp. 218 - 226, 1990. AbstractWebsite

The screening of 27 isolates grown on nitrogen-free medium for nitrogen-fixing ability resulted in the isolation of five organisms belonging to Bacillaceae, Enterobacteriaceae and Pseudomonadaceae. Estimates of N2-fixation efficiencies of these isolates indicated that they may be responsible for low rates of N2-fixation in soil. The possible association of these isolates as well as of Azotobacter and Azospirillum with wheat and barley was investigated in a greenhouse experiment. The highest values of nitrogenase activity on plant root were recorded in treatments inoculated with composite inocula of the isolated N2-fixers, particularly when Azotobacter and/or Azospirillum were added in combination. Inoculation with single inoculum of each of the N2-fixing isolates had no significant influence on plant growth, except with Pseudomonas and Bacillus for wheat and barley, respectively. Highly significant increases in growth of both plants were recorded in all cases of multistrain inoculation. © 1990 ACADEMIA, Publishing House of the Czechoslovak Academy of Sciences.

Fayez, M., "Bacterial composition and N2‐fixation of some Egyptian soils cultivated with wheat (Triticum aestivum L.)", Zeitschrift für Pflanzenernährung und Bodenkunde, vol. 152, issue 4, pp. 385 - 389, 1989. AbstractWebsite

The composition of the microflora, N2‐fixing bacteria particularly, in different soils cultivated with wheat in Egypt was investigated in some samples collected from the fields after applying the agricultural practices recommended for wheat cultivation and just before sowing. The influence of carbon sources, mineral nitrogen and water regimes on potential dinitrogen fixation (acetylene reduction assay) in soils was investigated. The bacterial population densities including‐N2‐fixing organisms were related to a number of environmental factors such as organic matter content. Among diazotrophs, Azotobacter spp. and Azospirillum spp. were encountered in higher densities in comparison with clostridia. Unamended soils showed a lower acetylene‐reducing activity (0.5–61.5 nmoles C2H4 g−1 h−1). Addition of glucose (1% w/w) greatly enhanced such activity being the highest (86.9–2846.5 nmoles C2H4 g−1 h−1) in the clay soil with the highest organic carbon content (1.42%). Glucose amendment had no significant influence on acetylene reduction in the saline soil. N2‐fixation in barley straw‐amended (1%) soils was not much higher than in unamended soils. Concentrations of up to 70 ppm ammonium‐nitrogen depressed N2‐fixation in soils that received barley straw. Acetylene reduction in submerged soil increased after addition of cellulose. Non‐flooded conditions favoured N2‐fixation in the fertile clay soil amended with sucrose. Copyright © 1989 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

El-Zanfaly, H. T., I. Hosny, M. Fayez, and A. Shaban, "Sanitary significance of fecal streptococci in underground water in Egypt.", Zentralblatt für Mikrobiologie, vol. 144, issue 5, pp. 299 - 304, 1989. AbstractWebsite

Underground water samples taken from 15 wells located at 3 municipal water works in Cairo were examined for the presence of fecal streptococci as a fecal pollution indicator. Fecal streptococci were detected in 96.4% of the 111 representative samples. Ranges of such pollution indicator were 1-17, 1-17 and 1-24 MPN/100 ml for water samples collected from wells in Mustorod, El-Marg and El-Maadi water works, respectively. A total of 200 pure strains of streptococci were isolated and subjected to biochemical and serological tests. Biochemical tests showed that only 26 strains could be classified as related to group D streptococci (enterococcus). Fore further identification, serological test was applied using 48 isolates chosen at random. The distribution of isolates among various serological groups showed that only 15 isolates (31%) could be classified into 5 defined groups (A, B, C, F and G). On the other hand, 4 isolates could not be defined serologically. The remaining 29 isolates (60%) gave a mixed reaction.

El-Zanfaly, H. T., I. Hosny, M. Fayez, and A. M. Shaban, "Incidence of antibiotic resistant bacteria in underground water", Environment International, vol. 14, issue 5, pp. 391 - 394, 1988. AbstractWebsite

Bacteria other than fecal coliform were isolated from the negative Eijkman test tubes by streaking on eosin methylene blue agar plates. A total of 101 isolates from underground water pumped from three water works in Cairo were classified into genera or groups according to their morphological, cultural and physiological characters and tested for their resistance towards four commonly used antibiotics namely chloramphenicol, tetracycline, neomycin, penicillin and one chemotherapeutic agent namely 2-sulfanilamide pyrimidine. Results showed that 77 and 64 isolates were resistant to penicillin and 2-sulfanilamide pyrimidine and in addition, 32 isolates were resistant to tetracycline. Only 18 and 8 isolates were resistant to chloramphenicol and neomycin, respectively. It was also found that 19 isolates belonging to 6 genera or groups were sensitive towards all of the tested compounds. © 1989.

Fayez, M., and Z. Y. Daw, "Effect of inoculation with different strains of Azospirillum brasilense on cotton (Gossipium barbadense)", Biology and Fertility of Soils, vol. 4, issue 1-2, pp. 91 - 95, 1987. AbstractWebsite

The response of the cotton plant to inoculation with six strains of Azospirillum brasilense was investigated under subtropical conditions in Egypt. Azospirilla populations and activities were increased as a result of root inoculation with liquid inoculum of Azospirillum sp. Highest C2H2 - reduction activities on roots were obtained with strains S631 and Sp Br 14 (means of 216.85 and 209.50 nmol C2H4g-1 root h-1 respectively) while strain M4 gave the lowest activity (mean of 100.8 nmol C2H4g-1 root h-1). Statistical analysis showed that Azospirillum strains 5631, Sp Br 14, E15 and SC22 significantly increased the plant dry weight and nitrogen uptake while inoculation with strains M4 and SE had no significant effect in that respect. © 1987 Springer-verlag.

Fayez, M., and R. R. Shahin, "Effects of industrial liquid wastes on dinitrogen fixation and microflora of soils and waters", Zeitschrift für Pflanzenernährung und Bodenkunde, vol. 150, issue 4, pp. 220 - 227, 1987. AbstractWebsite

Potential N2‐fixation was investigated in a number of samples representing soils and water courses under the effect of some industrial wastes in Helwan area of Egypt. Microbiological analysis of soil and water samples showed the general enrichment of fungi, actinomycetes and bacteria including N2‐fixers. Among asymbiotic N2‐fixers, azospirilla compared to azotobacters and clostridia were found to be present with rather higher densities in all samples tested. Generally, the microbial numbers increased by increasing the distance from the Industrial Complex at Helwan, which could be attributed to the high levels of salinity and total heavy metals near the factories. The results indicated that the industrial wastes near the factories exerted inhibitory effects on the acetylenereducing activity in soils, which seriously reduces their biological fertility. Such effects were decreased by getting away from the factories. Significantly negative correlations were recorded between densities of N2‐fixers or N2‐ase activity and salinity and total heavy metals content in both soil and water samples. Copyright © 1987 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

Nadia, F. E., M. Fayez, H. E. Makboul, and R. El‐Shahawy, "Occurrence and characterization of nitrogen‐fixing Azospirilla in some soils of Egypt", Zeitschrift für Pflanzenernährung und Bodenkunde, vol. 147, issue 2, pp. 210 - 217, 1984. AbstractWebsite

The occurrence and characterization of N2‐fixing azospirilla in some Egyptian soils has been investigated. Seven soils, representing a wide range in texture and properties were selected from different localities in Egypt. The highest nitrogenase activity reported for soil samples under investigation were related to numbers of N2‐fixing microorganisms (Azotobacter spp., Azospirillum spp., and Clostridium spp.). Seven strains of azospirilla were isolated and purified. Based on morphological characteristics, three types of cell morphology were distinguished. Cultural and physiological characteristics as well as nitrogenase activity of representative isolates in presence of different concentrations of NaCl were determined. According to the physiological properties studied, all isolates were classified as members of Azospirillum brasilense. Copyright © 1984 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

Fayez, M., N. F. Emam, and H. E. Makboul, "Interaction of the herbicides Bromoxynil and Afalon S with Azospirillum and growth of maize", Zeitschrift für Pflanzenernährung und Bodenkunde, vol. 146, issue 6, pp. 741 - 751, 1983. AbstractWebsite

The possible interaction of herbicides Bromoxynil and Afalon S with Azospirillumspp. and growth of maize was investigated in a greenhouse experiment. Neither inoculation nor herbicide application with or without inoculation had significant effect on the major groups of soil microflora (bacteria, actinomycetes, and fungi). The highest values of nitrogenase as well as dehydrogenase activity were recorded in treatment received only Azospirillum. Incorporation in soil of either Bromoxynil or Afalon S at the recommended field dose seemed to have no significant effect on the enzymatic activities, while application of these herbicides with Azospirillum had stimulatory effects in some cases. The application of either Bromoxynil or Afalon S significantly increased the dry weight of roots and shoots at 45 days period. The effect of herbicide on plant growth was more pronounced when applied with Azospirillum and the highest stimulatory effect was observed when Afalon S was applied with the N2‐fixing microorganism. Copyright © 1983 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

Monib, M., Y. Abd-el-Malek, I. Hosny, and M. Fayez, "Associative symbiosis of Azotobacter chroococcum and higher plants.", Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene. Zweite naturwissenschaftliche Abteilung: Mikrobiologie der Landwirtschaft der Technologie und des Umweltschutzes, vol. 134, issue 2, pp. 133 - 139, 1979. AbstractWebsite

The association between a selected strain of Azotobacter chroococcum and seven plants was investigated in water cultures under sterile conditions. Azotobacter population progressively increased in the nutrient solution and on the rhizoplane. Microbial propagation depends on the type of plant, being much higher in presence of wheat, followed by barley, maize, broad bean, and cotton, while in presence of fenugreek and lentil lower rates of multiplication were recorded. Inoculation increased the dry weight of plants by 5--12% and in length by 3--18% in addition to increased nitrogen content of plants and nutrient solution. Nitrogen balance showed no significant change in systems devoid of Azotobacter, but association between plants and the microorganism invariably showed positive results. The extent of N2-fixation depends on the type of plants; higher gains were recorded in presence of non-leguminous plants.

Monib, M., Y. Abd-el-Malek, I. Hosny, and M. Fayez, "Effect of Azotobacter inoculation on plant growth and soil nitrogen.", Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene. Zweite naturwissenschaftliche Abteilung: Mikrobiologie der Landwirtschaft der Technologie und des Umweltschutzes, vol. 134, issue 2, pp. 140 - 148, 1979. AbstractWebsite

The validity of seed bacterization with Azotobacter chroococcum in soils of variable densities of naturally present azotobacters was studied. Inoculation of barley grains had no effect on counts of total microflora, neither in rhizosphere nor in root-free soil, but significantly increased Azotobacter population, especially in the rhizosphere. The rate of colonization in the root region was much higher when soil initially harboured low Azotobacter densities. Bacterization improved plant growth and increased soil nitrogen through nitrogen fixation. Nitrogen balance in soils showed higher gains in the inoculated treatments over the uninoculated analogues of 30--98 ppm.

Monib, M., Y. Abd-el-Malek, I. Hosny, and M. Fayez, "Seed inoculation with Azotobacter chroococcum in sand cultures and its effect on nitrogen balance", Zentralblatt fur Bakteriologie Parasitenkunde Infektionskrankheiten und Hygiene Zweite Abteilung, vol. 134, issue 3, pp. 243 - 248, 1979. AbstractWebsite