Nitrogen Biofertilizer Research Articles

Assessing Nitrogen Biofertilizer Microbeads Formula and Inorganic Nitrogen Fertilizer on Nitrogen Uptake and Agronomic Traits of Maize

Assessing Nitrogen Biofertilizer Microbeads Formula and Inorganic Nitrogen Fertilizer on Nitrogen Uptake and Agronomic Traits of Maize

Comparison between nitrogen biofertilizers source (blue green algae and bacteria) on growth of date palm plantlets (Phoenix dactylifera ‘Malacabe’) during acclimatization stage

Comparison between nitrogen biofertilizers source (blue green algae and bacteria) on growth of date palm plantlets (<i>Phoenix dactylifera</i> ‘Malacabe’) during acclimatization stage

Application Technique and Dosage of Halotolerant Nitrogen Biofertilizer for Increasing Soil Total N, N Uptake, Chlorophyll Content, Photosynthate Accumulation and Growth of Rice Plants in Saline Ecosystem

Utilization of halotolerant nitrogen biofertilizer can increase N uptake and promote growth and yield of rice plants in saline ecosystem. Halotolerant nitrogen biofertilizer can be applied to seed and seedling in certain dosage. The aim of this study was to obtain the application technique and dosage that can increase N uptake and promote growth and yield of rice plants in saline ecosystem. The research was conducted in the greenhouse in Kawarang District (Indonesia) from September until November 2020. There was used randomized block design which consisted of two factors with three replications. The first factor was application techniques, i.e. seed treatment, nursery treatment, and seed + nursery treatment. The second factor was dosage of halotolerant nitrogen biofertilizer, i.e. 0, 500, 1,000, 1,500 and 2,000 g ha-1. The results showed that halotolerant nitrogen biofertilizer applied in seed and nursery treatment can increase N uptake and plant height by 3.95 g plant-1 and 34.50 cm, respectively. Dosage of 1,500 g ha-1 can increase the total N of soil (0.26%), chlorophyll content (46.97 SPAD), photosynthate accumulation (3.33 g), and rice yield (13.40 t/ha). Application of halotolerant nitrogen biofertilizer in seed and nursery technique at a dosage of 1,500 g ha-1 can be further recommendation in rice cultivation on saline ecosystems.

Effect of Different Carrier Composition on Viability of Halotolerant N-Fixing Rhizobacteria, Water Content and pH Level in Nitrogen Biofertilizer for Saline Ecosystem

The use of saline soils as productive agricultural land poses major challenges. The utilization of nitrogen biofertilizer with halotolerant N-fixing rhizobacteria as the active material at the right dosage can increase soil productivity and support plant growth. The aim of this study was to obtain the composition of the carrier material that can maintain rhizobacteria viability, water content, and pH of nitrogen biofertilizer and to obtain the right dosage to increase the growth of rice plants in saline ecosystems. The research location was at Microbiology Laboratory of CV Bintang Asri Arthauly, Bandung and greenhouse of Jayamukti Village, Banyusari District, Karawang Regency from February to November 2020 used completely randomized design. The viability test consisted of nine treatments, while the application dosage test consisted of 13 treatments and repeated three times. The result showed that the H carrier composition (50% peat + 17.5% compost + 17.5% biochar + 5% dolomite + 5% guano + 5% nutrition) was able to maintain high viability of halotolerant N-fixing rhizobacteria compared to other treatments (10.22 x 10 7 CFU mL -1 ). Water content (34.50%) and pH level (7.9) in the composition H also meet the quality standard requirements of the biofertilizer, respectively. Nitrogen biofertilizer with H carrier composition at a dosage of 1500 g ha -1 applied to seed and nursery can increase the height and biomass of rice plants grown under saline condition. Further research is needed on the application of nitrogen biofertilizers in saline soil that can increase the effectiveness of N fertilization. Keywords : Carrier ∙ Rhizobacteria ∙ Rice ∙ Saline ecosystem ∙ Viability Abstrak Penggunaan tanah salin sebagai lahan pertanian produktif memiliki tantangan yang besar. Pemanfaatan pupuk hayati nitrogen dengan rhizobakteri penambat N halotoleran sebagai bahan aktifnya pada dosis yang tepat dapat meningkatkan produktivitas tanah dan mendukung pertumbuhan tanaman padi. Penelitian bertujuan mendapatkan komposisi bahan pembawa yang dapat mempertahankan viabilitas rhizobakteri, kadar air, dan pH pupuk hayati nitrogen serta mendapatkan dosis yang tepat untuk meningkatkan pertumbuhan tanaman padi pada ekosistem salin. Lokasi penelitian di Laboratorium Mikrobiologi CV Bintang Asri Arthauly Bandung dan rumah kaca Desa Jayamukti, Kecamatan Banyusari, Kabupaten Karawang sejak bulan Februari sampai November 2020. Metode percobaan menggunakan metode eksperimental dengan Rancangan Acak Lengkap. Uji viabilitas terdiri dari sembilan perlakuan, sedangkan uji dosis aplikasi pupuk hayati terdiri dari 13 perlakuan dan masing-masing diulang sebanyak tiga kali. Hasil menunjukkan bahwa komposisi bahan pembawa H (Gambut 50% + kompos 17.5% + biochar 17.5% + dolomit 5% + guano 5% + nutrisi 5%) mampu mempertahankan viabilitas rhizobakteri penambat N halotoleran yang tinggi dibandingkan perlakuan lainnya yaitu sebesar 10,22 x 10 7 CFU/mL. Kadar air dan pH level pada komposisi H juga memenuhi syarat baku mutu pupuk hayati yaitu sebesar 34.50% dan 7.9. Pupuk hayati dengan komposisi bahan pembawa H dengan dosis 1500 g ha -1 yang diaplikasikan pada benih dan persemaian mampu meningkatkan tinggi dan biomassa tanaman padi yang ditanam pada kondisi salin. Perlu penelitian lebih lanjut mengenai aplikasi pupuk hayati N di tanah salin yang dapat meningkatkan efektivitas pemupukan N. Kata Kunci : Bahan pembawa ∙ Ekosistem salin ∙ Padi ∙ Rhizobakteria ∙ Viabilitas

Potential of Phototrophic Purple Nonsulfur Bacteria to Fix Nitrogen in Rice Fields.

Biological nitrogen fixation catalyzed by Mo-nitrogenase of symbiotic diazotrophs has attracted interest because its potential to supply plant-available nitrogen offers an alternative way of using chemical fertilizers for sustainable agriculture. Phototrophic purple nonsulfur bacteria (PNSB) diazotrophically grow under light anaerobic conditions and can be isolated from photic and microaerobic zones of rice fields. Therefore, PNSB as asymbiotic diazotrophs contribute to nitrogen fixation in rice fields. An attempt to measure nitrogen in the oxidized surface layer of paddy soil estimates that approximately 6–8 kg N/ha/year might be accumulated by phototrophic microorganisms. Species of PNSB possess one of or both alternative nitrogenases, V-nitrogenase and Fe-nitrogenase, which are found in asymbiotic diazotrophs, in addition to Mo-nitrogenase. The regulatory networks control nitrogenase activity in response to ammonium, molecular oxygen, and light irradiation. Laboratory and field studies have revealed effectiveness of PNSB inoculation to rice cultures on increases of nitrogen gain, plant growth, and/or grain yield. In this review, properties of the nitrogenase isozymes and regulation of nitrogenase activities in PNSB are described, and research challenges and potential of PNSB inoculation to rice cultures are discussed from a viewpoint of their applications as nitrogen biofertilizer.

Triticale forage crop quality as affected by water stress and nitrogen biofertilizer in an arid climate

Understanding the interactive effect of water and nitrogen (N) availability is a crucial issue for stabilizing cereal forage production in the arid areas. A two-year side by side experiment (2015-2016 and 2016-2017 growing seasons) was carried out under different N sources and water regimes in a typical arid environment (Darab, Iran) to evaluate the forage quality of triticale (×Triticosecale Wittmack) crop.There were two irrigation regimes [normal irrigation (IRN) and cutting off irrigation after crop anthesis stage (IRMD)]. Rain-fed treatment (IR0) was included in the second year. Three N sources including Azospirillum brasilense (biofertilizer, Bio), Azospirillum brasilense + 75 kg N ha-1 as urea (Bio + N75), 150 kg N ha-1 as urea (N150) and unfertilized plots (N0 ascontrol) were used. Water stress decreased leaf-stem (L/S) ratio, dry mater (DM) and dry matter digestibility (DMD) and increased crude forage protein (CP), neutral detergent fiber (NDF) and ash contents. However, the effect of water stress on forage ash, DMD, ADF contents, L/S ratio (in 2015-2016 growing season) and CP content depended on N sources. In Bio + N75, triticale forage had the highest CP content, DMD, ash and L/S ratio (in 2015-2016 growing season) and the lowest ADF compared with the other N sources under water stress conditions. According to the results of this study, it can be suggested that the integration of biofertilizer and chemical N fertilizer be successfully used to increase the quality of triticale forage under deficit irrigation regimes in sustainable farming systems in arid conditions.

Leaf gas exchange and chlorophyll index in guava fertirrigated with bovine biofertilizer and nitrogen

The objective of this work was to evaluate the influence of fertirrigation with nitrogen and liquid bovine biofertilizer on gas exchange and leaf chlorophyll index of 'paluma' guava (Psidium guajava L.). The experimental design was randomized blocks with treatments distributed in a factorial arrangement (2 × 4) referring to mineral fertilizing with N (50% and 100% of N recommended) and biofertilizer concentrations (0, 2.5, 5.0 and 7.5% of the fertirrigated volume). Variables evaluated were chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll indexes (Chltotal), internal CO2 concentration (Ci), stomatal conductance (gs), transpiration (E), net photosynthesis (A), instant carboxylation efficiency (iCE) and water use efficiency (WUE). The biofertilizer significantly affected Chl a, Chl b, Chltotal, A, gs and E, with quadratic polynomial adjustment of the results. However, there was no effect of N fertilization and interaction between the factors. Maximum index of Chltotal was 32.31 obtained with the estimated dose of 3.8% of the biofertilizer; while A, gs and E presented maximum responses of 19.09 µmol of CO2 m-2 s-1, 0.28 mol of H2O m-2 s-1 and 4.93 mmol of H2O m-2 s-1, with estimated doses of 3.6%, 3.6%, and 3.7%, respectively. Generally, liquid bovine biofertilizer applied via fertirrigation affects positively the photosynthetic responses in 'paluma' guava, however, with decreasing effects for doses above 3.8%.

Effect of Nanofertilizers and Biofertilizers on Yield of Maize: Biplot Analysis

AbstractOne of the newest and most interesting fields of science is nanotechnology, which is exploiting many areas such as life sciences; however, its application in agriculture is rarely studied. In order to examine the environmentfriendly fertilizers (nano-sized and biological fertilizers), and control the agricultural nonpoint source pollution from the source, a field experiment was arranged to study the effects of bulk fertilizers (NPK, nitrogen biofertilizer, and phosphorus biofertilizer), nanofertilizers (nanoboron, nanozinc and nanocomplete) and no fertilizer treatment (control) on morphological traits of maize. The first two Principal Components (PCs) were used to create a biplot, which accounted for 72% of the variance of the treatment × trait interaction. The nanozinc fertilizers following nanoboron fertilizer were the best in most of the biological yield, seed yield, harvest index, and 100-grain weight. The vector-view biplot revealed a strong positive association between chlorophyll and protein content, seed yield with the number of kernels per ears and the number of rows per kernel. Nanocomplete fertilizer was the best treatment for chlorophyll content, protein percent and straw yield, while NPK did not high increase in the most traits of maize. This investigation indicated that treatment × trait biplot can graphically show the interrelationships among traits and facilitate visual comparison of fertilizers. In conclusion, it was found that zinc and boron nanofertilizers increased the production of most of the traits in maize. This study indicated that nano types of fertilizers could promote the studied traits in maize plant.

Influence of Magnetized Water and Nitrogen Bio-fertilizers on the Quantity and Quality Features of the Butternut Squash Cucurbita moschata

The present study was carried out at Baqubah Nursery, Directorate of Agriculture, Diyala Province, Iraq, during the period of March to October 2017, to investigate the effects of magnetized water with bio and chemical fertilizers on the butternut squash. A factorial experiment with three replications was conducted and two factors were investigated; the state of water (magnetized water and non-magnetized water) and the fertilizer type (chemical fertilizer: urea 100 kg N/ hectare; bio-fertilizers: Azotobacterchroococcum and Azospirillumbrasilense + chemical fertilizer in 1:1 ratio).&#x0D; The results revealed that the magnetized water with bio + chemical fertilizers recorded the highest rate of fruit weight that reached 786.0 ,807.3 and 775.3 g at the first, second and third harvests, respectively. The effect of the magnetized water was significant on the rate of fruit yield/plant which reached 3745.0 g at the first harvest, while bio + chemical fertilizer recorded the highest rate that reached 2419.8 and 1404.3 g at the second and the third harvests, respectively. Magnetized water with bio + chemical fertilizers showed significant increments in total yield / plant (7822.3 g) and total yield / hectare (31289.3 kg). The treatment with magnetized water and bio and chemical fertilizer were significant in fruit content of total soluble solid (TSS %) after 185 days, which reached 13.0 % and 12.2 %, respectively, while bio + chemical fertilizer was superior in the yield of fructose sugar and fibers which reached 10.4 and 12.7 % , respectively.

Improving grain yield, water and nitrogen use efficiency of Nigella sativa with biological and chemical nitrogen under different irrigation regimes

Biofertilizers are an important source for completing the plant nutrition program, which has a significant effect on reducing the cost and adverse effects of chemical fertilizers and increasing plant resistance to environmental stresses. The aim of this study was to investigate the effect of Nitroxine and nitrogen biofertilizer on grain yield, nitrogen utilization and use efficiency, nitrogen remobilization and plant water use efficiency in Nigella sativa (black cumin) grown under different irrigation regimes. The experiment was conducted at Yasouj University Research Field in split plots in a randomized complete block design with three replications in 2016 and 2018. Factors studied in this experiment consisted of four irrigation regimes (based on phenological stages) including weekly irrigation from emergence to harvest (WI0) and withholding irrigation from blooming to maturity (WIb), from flowering to maturity (WIf), and from the start of grain formation to maturity (WIs) as a main factor and five levels of fertilizer including no application of fertilizers (N0), 80 kg N ha−1 (N80), 40 kg N ha−1 (N40), combination of 40 kg N ha-1+Nitroxin biofertilizer (N40 + B), and Nitroxin biofertilizer (B) as sub factors. Application of 80 kg N ha-1 in complete irrigation, and combination of 40 kg N ha-1+Nitroxin biofertilizers in other irrigation regimes were associated with greatest grain yield, N content in aerial organs and water use efficiency. In all irrigation regimes, combination of 40 kg N ha-1+Nitroxin biofertilizers resulted in the greatest N remobilization (N already has been stored in the vegetative organs, transferred to the developing grains) rate (12.46 kg ha-1). The greatest N utilization efficiency was obtained in non-fertilizer treatments (15.1 kg kg-1) and withholding irrigation from flowering stage (15.7 kg kg-1). Finally, the results showed that the application of nitroxin biofertilizer can reduce the use of urea chemical fertilizer and mitigate the effects of drought stress by N fixing and possibly producing growth hormones and decrease N utilization and water use efficiency.

Đánh giá hiệu quả của chế phẩm đạm sinh học Burkholderia vietnamiensis CT1 trên giống lúa cao sản OM4218

Nitrogen biofertilizer was made from Burkholderia vietnamiensis CT1 in Burk&#39;s liquid without nitrogen (Park et al., 2005). It was stored for more than 3 months, then mixed with germinated seeds of high-yield rice (cv. OM4218). The efficacy of Burkholderia vietnamiensis CT1 was investigated on the OM4218 rice growth under pots condition, in the summer-autumn crop of 2016. The results showed that nitrogen biofertilizer of the Burkholderia vietnamiensis CT1 could replace up to 50% of N used for high-yield rice grown in pots, which had a significant effect on biomass accumulation, number of effective shoots of rice bush and the yild of rice harvested per pot compared to the control. The effect of nitrogen biofertilizer also affected significantly the accumulation of protein in the rice kernel and maintained the total N in the soil after rice harvest. In conclusion, Burkholderia vietnamiensis CT1 can provide up to 50% of the biological nitrogen needed for the growth and development of the OM4218 high-yield rice planted in pots.

Effects of Nitrogen and Phosphate Biofertilizers on Morphological and Agronomic Characteristics of Sesame (&amp;lt;i&amp;gt;Sesamum indicum&amp;lt;/i&amp;gt; L.)

In order to investigate the effects of Barvar-2 phosphate biofertilizer and nitroxin biofertilizers on agronomical characteristics of sesame, an experiment was carried out as factorial based on randomized complete block design with three replications and two factors in Khoy city, northwest of Iran, in 2014 growing seasons. The factors were as follows: phosphorus fertilizer in three levels (control, barvar-2 phosphate bio-fertilizer with 100 kg triple superphosphate per hectare and 200 kg triple superphosphate per hectare) and nitrogen fertilizer in four levels (control, nitroxin bio-fertilizer with urea at rate of 100 kg·ha−1, nitroxin biofertilizer with urea at rate of 150 kg·ha−1 and urea at rate of 200 kg·ha−1). The results showed that a significant effect of nitrogen and phosphate biofertilizer, on plant height, branches per plant, pods per plant, seed in pod, oil percent, seed yield and harvest index. Maximum seed yield of 1274.37 and 1232.5 kg·ha−1 was obtained from treatments of 200 kg·ha−1 triple superphosphate and barvar-2 phosphate biofertilizer besides 100 kg·ha−1 triple superphosphate. For nitrogen biofertilizer, maximum seed yield of 1264.83 and 1246.12 kg·ha−1 was obtained from treatments of 200 kg·ha−1 urea and nitroxin biofertilizer besides urea 150 kg·ha−1 respectively. According to the results of this experiment, consumption of chemical fertilizer of triple super phosphate was reduced equal to 50% using Barvar-2 phosphate biofertilizer and consumption of chemical fertilizer of urea was reduced equal to 25% using nitroxin biofertilizer.

Evaluation of inoculation with nitrogen and phosphorus biofertilizers on yield and radiation use efficiency of black cumin (Nigella sativa L.) under Mashhad climatic conditions

ABSTRACTThe purposes of this study were evaluate the effects of biofertilizers inoculation on growth indices, yield and radiation use efficiency (RUE) in black cumin under Mashhad climatic conditions. This field experiment was carried out based on a randomized complete block design with three replications. This experiment was performed at Agricultural Research Station, Ferdowsi University of Mashhad, Iran, during two growing seasons 2007–2008 and 2008–2009. Treatments were (A) Azotobacter paspali, (B) Azospirillum brasilense, (C) Rhizophagus irregularis, A + C, B + C, A + B, A + B + C and control. In all treatments, except control, 100 g of seeds were inoculated with15 mg of each biofertilizer. Results indicated that leaf area index (LAI) and accumulative dry matter (DM) showed an increasing trend up to 1863°Cd and a short declining trend afterwards. The relation between accumulative DM and absorbed photosynthesis active radiation (PARa) was linear. Radiation use efficiency (RUE) fluctuated from 0.55 gMJ−1 (control) to 0.89 gMJ−1 (B+C). Inoculation with biofertilizers enhanced root development and hence availability of moisture and nutrients, particularly nitrogen and phosphorus. Since these ecological fertilizers produce many growth regulators for the plant which promote LAI and accumulative DM and therefore yield, PARa and RUE enhanced.

Effect of Nitrogen Biofertilizers on Yield and Yield Components of Different Maize (Zea mays L.) Cultivars

In order to evaluate the effect of nitrogen bio-fertilizers on yield and yield and yield components of different maize (zea mays L.) cultivars a field experiment was conducted in Islamic Azad University of Boroujerd, Iran (at Isfahan region), during the growing seasons 2013- 2014. The experiment was laid out in a split-plot design based on randomized block design with three replications. Treatments were different cultivars (Siloking, NS4015, Maxima and SC704) in main plots and nitrogen bio-fertilizers (Azotobacter, Nitroxin and Supernitroplus) with control in sub plots. The results reviled that the effect of cultivar treatmenton all traits was significant. Effect of N bio-fertilizer treatment was significant on stem weight, leaf weight, ear weight and biomass yield only. Interaction effect of them was significant on all traits excepting number of leaf per plant and ear weight. Application of nitrogen biofertilizers increased yield components of different cultivars of maize specially, for Siloking cultivar and Supernitroplus bio-fertilizer. Siloking cultivar with application of Supernitroplus biofertilizer had the highest plant height and leaf weight and Maxima cultivar with application of Nitroxin biofertilizer had the lowest plant height and leaf weight. However, NS4015 cultivars with non-application of any of N biofertilizer had the highest stem weight. Siloking cultivar had the highest number of leaf per plant and NS4015 cultivar had the lowest number of leaf per plant. Siloking cultivar had the highest all of the traits excepting stem weight. So, this cultivar was more useful than other cultivars for achieve to maximum production of foliage in Isfahan province. However Siloking cultivar with application of Supernitroplus nitrogen biofertilizer treatment had the highest biomass yield as foliage yield and we propose this treatment for maximum production of maize in Isfahan environmental condition.DOI: http://dx.doi.org/10.3126/ijls.v9i5.12711

Biopriming and mineral fertilizers effects on agronomical performance of rapeseed (Brassica napus L.)

Increasing and extending the role of biofertilizers can reduce the need for chemical fertilizers and decrease adverse environmental effects. They can play a significant role in fixing atmospheric nitrogen and production of plant growth promoting substances. Therefore, in the development and implementation of sustainable agriculture techniques, biofertilization has great importance in alleviating environmental pollution and deterioration of nature. In order to study the effects of mineral nitrogen fertilization and biofertilizer inoculation on grain yield and its components of rapeseed ( Brassica napus L.) under different levels of sulfur fertilizer, a field experiment in Factorial scheme based on Randomized Complete Block design was conducted in three replications. Experimental factors were as follows: (i) Four levels of chemical nitrogen fertilizer (0, 100, 150 and 200 kg N ha –1 ), (ii) Two levels of biofertilizer (with and without inoculation) containing Azotobacter sp. and Azospirillum sp. and (iii) Two levels of sulfur application (0 and 50 kg S ha –1 ). Rapeseed yield and yield components had a strong association with the N fertilization, biofertilizer inoculation and S application. Higher rates of N fertilization, biofertilizer inoculation and S application increased plant height, pods number plant –1 , grains number pod –1 , 1000-grains weight, grain yield and biological yield. It seems that moderate N rate (about 150 kg N ha –1 ) and S application (about 50 kg S ha –1 ) can be beneficial to improve growth, development and total yield of inoculated rapeseed plants. So, it is suggested to use a combination of organic and inorganic fertilizer to achieve the highest yield without a negative effect on grain quality that will lead to sustainable environment.

Whole Forage Barley Crop Quality as Affected by Different Deficit Irrigation and Fertilizing Systems

Effects of organic, biological, and chemical fertilizers along with water-deficit regimes were investigated on forage barley in a field experiment during 2007–2008. Irrigation regimes were nonstressed (NS), moderately stressed (MS), and severely stressed (SS) and fertilizer treatments were no fertilizer (NF), phosphorus and nitrogen biofertilizers (BF), chemical fertilizer (CF), vermicompost (VC), chemical fertilizer + vermicompost (CV), and chemical fertilizer + biofertilizer (CB). Water stress reduced leaf/stem ratio and dry-matter digestibility (DMD), but increased crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF). However, the effect of water deficit on DMD, ash, and NDF depended on the fertilizer treatment. In BF and CV, the barley forage had the greatest DMD and least ash and NDF under water-deficit conditions. The integrated fertilizing systems are more reliable than conventional systems to produce high-quality forage barley in arid environments with late water stress or water deficit irrigation system.

Oxidative stress management in the filamentous, heterocystous, diazotrophic cyanobacterium, Anabaena PCC7120.

Reactive oxygen species (ROS) are inevitably generated as by-products of respiratory/photosynthetic electron transport in oxygenic photoautotrophs. Unless effectively scavenged, these ROS can damage all cellular components. The filamentous, heterocystous, nitrogen-fixing strains of the cyanobacterium, Anabaena, serve as naturally abundant contributors of nitrogen biofertilizers in tropical rice paddy fields. Anabaena strains are known to tolerate several abiotic stresses, such as heat, UV, gamma radiation, desiccation, etc., that are known to generate ROS. ROS are detoxified by specific antioxidant enzymes like superoxide dismutases (SOD), catalases and peroxiredoxins. The genome of Anabaena PCC7120 encodes two SODs, two catalases and seven peroxiredoxins, indicating the presence of an elaborate antioxidant enzymatic machinery to defend its cellular components from ROS. This article summarizes recent findings and depicts important perspectives in oxidative stress management in Anabaena PCC7120.

Effect of ATP and 2-oxoglutarate on the in vitro interaction between the NifA GAF domain and the GlnB protein of Azospirillum brasilense

Azospirillum brasilense is a diazotroph that associates with important agricultural crops and thus has potential to be a nitrogen biofertilizer. The A. brasilense transcription regulator NifA, which seems to be constitutively expressed, activates the transcription of nitrogen fixation genes. It has been suggested that the nitrogen status-signaling protein GlnB regulates NifA activity by direct interaction with the NifA N-terminal GAF domain, preventing the inhibitory effect of this domain under conditions of nitrogen fixation. In the present study, we show that an N-terminal truncated form of NifA no longer required GlnB for activity and lost regulation by ammonium. On the other hand, in trans co-expression of the N-terminal GAF domain inhibited the N-truncated protein in response to fixed nitrogen levels. We also used pull-down assays to show in vitro interaction between the purified N-terminal GAF domain of NifA and the GlnB protein. The results showed that A. brasilense GlnB interacts directly with the NifA N-terminal domain and this interaction is dependent on the presence of ATP and 2-oxoglutarate.

Inoculation of &lt;i&gt;Bacillus sphaericus&lt;/i&gt; UPMB-10 to Young Oil Palm and Measurement of Its Uptake of Fixed Nitrogen Using the &lt;sup&gt;15&lt;/sup&gt;N Isotope Dilution Technique

There are increasing applications of diazotrophic rhizobacteria in the sustainable agriculture system. A field experiment on young immature oil palm was conducted to quantify the uptake of N derived from N2 fixation by the diazotroph Bacillus sphaericus strain UPMB-10, using the 15N isotope dilution method. Eight months after 15N application, young immature oil palms that received 67% of standard N fertilizer application together with B. sphaericus inoculation had significantly lower 15N enrichment than uninoculated palms that received similar N fertilizers. The dilution of labeled N served as a marker for the occurrence of biological N2 fixation. The proportion of N uptake that was derived from the atmosphere was estimated as 63% on the whole plant basis. The inoculation process increased the N and dry matter yields of the palm leaflets and rachis significantly. Field planting of young, immature oil palm in soil inoculated with B. sphaericus UPMB-10 might mitigate inorganic fertilizer-N application through supplementation by biological nitrogen fixation. This could be a new and important source of nitrogen biofertilizer in the early phase of oil palm cultivation in the field.

Improved Eco-Friendly Recombinant Anabaena sp. Strain PCC7120 with Enhanced Nitrogen Biofertilizer Potential

Photosynthetic, nitrogen-fixing Anabaena strains are native to tropical paddy fields and contribute to the carbon and nitrogen economy of such soils. Genetic engineering was employed to improve the nitrogen biofertilizer potential of Anabaena sp. strain PCC7120. Constitutive enhanced expression of an additional integrated copy of the hetR gene from a light-inducible promoter elevated HetR protein expression and enhanced functional heterocyst frequency in the recombinant strain. The recombinant strain displayed consistently higher nitrogenase activity than the wild-type strain and appeared to be in homeostasis with compatible modulation of photosynthesis and respiration. The enhanced combined nitrogen availability from the recombinant strain positively catered to the nitrogen demand of rice seedlings in short-term hydroponic experiments and supported better growth. The engineered strain is stable, eco-friendly, and useful for environmental application as nitrogen biofertilizer in paddy fields.