Rhizosphere includes many microorganisms which show different types of interactions with the soil. Rhizospheric effect is more in bacteria than any other soil microorganisms. Rhizospheres help in bioremediation. Some bacteria namely Pseudomonas, Aerobacter, Agrobacterium have the ability to solubilize the insoluble inorganic phosphates like tricalcium phosphate, rockphosphate etc. Some enzyme producing microorganisms like Triticum viridae which produces cellulase and chitinase degrades cellulose and chitin respectively. In the rhizospheric soil some nitrogen fixing bacteria are found like Azorhizobium, Allorhizobium, Rhizobium. Some free-living bacteria found helps in the plant growth. Some organic acid
Phosphorous is second only to nitrogen as an essential macronutrient for plant growth and development (Schefferet al., 1998). Soil is rich in insoluble mineral and organic phosphates but deficient in available orthophosphate (Pi) (Dadarwalet al., 1997). Phosphorus is a vital component of ATP, the "energy unit" of plants. ATP is formed during photosynthesis, has phosphorus in its structure. Soil amendment with phosphatic fertilizer, produced via chemical processing of rockphosphate ore, is therefore an absolute requirement in order to feed the world's population. For over one hundred years, workers have recognized the ability of soil microorganisms to solubilize Pi from insoluble (i.e. nutritionally unavailable) organic and mineral phosphates (Whitelaw, 2000). Wide ranges of microbial
Hydrocolloids of each kind of nanoparticle (200 µ L) were separately added to the microorganism suspensions (200 µ L). Control samples of microorganisms were treated with Milli-Q water. The samples were gently mixed for 15 minutes and then droplets of samples were put on Formvar-coated 300 mesh Cu grids (Agar Scientific Ltd, Stansted, UK). In this way, the inspected object was observable after a very short time of interaction of nanoparticles with the living microorganisms. The samples were dried at room tempera- ture, in sterile conditions, and observed using a JEM-2000EX TEM at 200 keV (JEOL). The applied voltage was chosen to avoid any damage to the sample. The method developed enabled direct observation of the initial interface between nanoparticles and microorganisms, particularly including visualization of small amounts of a substance excreted from the microorganisms.
The primary biological importance of phosphates is as a component of nucleotides, which serve as energy storage within cells (ATP) or when linked together, form the nucleic acids DNA and RNA. The double helix of our DNA is only possible because of the phosphate ester bridge that binds the helix. Besides making bio-molecules phosphorus is also found in bones, whose strength is derived from calcium phosphate in enamel o f m a m m a l i a n t e e t h ; exoskeleton of insects and phospholipids (found in a biological membranes) It also functions as buffering agent in maintaining acid base homeostasis in the human body.
Erlenmeyer flasks, individual rockphosphate types (Malian RP, Moroccan RP, Algerian RP, or Mexican RP) was added to the medium at the concentration of 5gL -1 and the pH adjusted to 7.5. After sterilisation and cooling, 200 µl mycelia suspensions were used to inoculate flasks containing the different rock phosphates in triplicate. Triplicate non-inoculated flasks supplemented with the different rock phosphates served as controls. Incubation was made at 28 °C, 150 rpm for 7 days. Cultures were then transferred into sterile falcon tubes, centrifuged at 10000 rpm for 10 minutes and aliquots taken for both P and pH measurement.
In Ethiopia, several authors isolated phosphate solubilizing microorganisms (PSM). The studies [10, 11] showed diversity in PS among the isolatesEvaluated the P solubilization in vitroon solid medium. In liquid medium by measuring P release fromDifferent P sources such as Rock phosphtes (Egyptian RF, Bikillal RF, bone phosphates)Showed plant growth through inoculation of PSM of different crops. It has also been documented that different species of PSB isolated from Ethiopian soils were able to release phosphate from insoluble P sources such as tricalcium phosphate, hydroxyl apatite, rockphosphate and old bone [10, 12, 13]. Recently, emerging evidences indicated that, besides increased P uptake, the production of phytohormones such as indole acetic acid (IAA) and suppression of different soil borne phytopathogens by PSB could also play an imperative role in plant growth promotion [14-17]. Several reports demonstrated that inoculation of PSB which exhibited multiple plant growth promoting activities significantly improved plant growth and yield under glasshouse and field conditions [16, 17].
Phosphate fertiliser rates applied to arable crops generally range from 20 to 80 kg P/ha according to crop species and the plant-available P concentration of the soil, although on soils with high P-fixing capacity rates of 100 to 200 kg P/ha may be applied (Mengel et al., 2001). In a UK study of 22 field experiments with potatoes, Allison et al. (2001) found that no yield benefit was attained when P fertilisers were applied to soils with an Olsen P value >26 mg/L. However, on a silt loam soil 3 in New Zealand, Prasad et al. (1988) found that maximum potato yield corresponded with an Olsen P ca. 70 mg/L in both years studied with a target value of 54-63 mg/L deemed optimal; target values for other crops ranged from >110 mg/L for winter spinach (Spinacia oleracea L.) to as low as 28 mg/L for sweet corn. Allison et al. (2001) showed increases in tuber numbers and yield were achieved when soluble P fertilisers were applied to soils with Olsen P <16 mg/L and 23 mg/L respectively. Therefore in organic cropping operations where the increase in plant-available P in response to PR application is small and delayed
The model in its current form does not include calcifiers as a dedicated functional group given the limited knowledge of the physiological constraint of calcification. Therefore, the process of calcification is not directly modelled, but is treated implicitly by considering part of the nanophytoplankton to act as calcifiers. Calcification processes are inferred from the system dynamics based on the assumption of a given ra- tio between particulate inorganic carbon over particulate or- ganic carbon in sedimenting material, usually referred to as the rain ratio. Here this ratio is used as a proxy for the cal- cite production matching the local increase of POC originat- ing from nanophytoplankton. Since the rain ratio has been defined for the sinking fluxes and calcite is the more resis- tant mineral, we limit the description to calcite in this part of the model, neglecting aragonite. This approach is simi- lar to the implementations in other biogeochemical models, e.g. PISCES (Gehlen et al., 2007) or MEDUSA (Yool et al., 2013).
Bengal gram (Cicer arietinum L.) is a prime pulse crop in India next only to pigeonpea. Though it occupies an area to a greater extent, its productivity is low as compared to its potential yield in the experimental station (Kumar, 1997). Number of factors is responsible for its low productivity. Among them, imbalanced nutrition is an important factor affecting the yield of Bengal gram to a greater extent. To enhance the productivity of this crop, application of organic manures with rockphosphate, phosphorus solubilizing bacteria and seed treatment with rhizobium are of great importance.
2004). As phosphate is an important inorganic nutrient for zooxanthellae (Deane and O’Brien, 1981; Jackson and Yellowlees, 1990; Belda et al., 1993), it is possible that the observed phosphate depletion of Artemia nauplii was due to assimilation by zooxanthellae. When estimating heterotrophic nutrient input from feeding on zooplankton, it is important to take digestive efficiency into account. Previous studies have assumed a 100% assimilation of available carbon from zooplankton during intracoelenteric digestion (Fabricius et al., 1995; Sebens et al., 1996; Sebens et al., 1998; Houlbrèque et al., 2004; Grottoli et al., 2006; Purser et al., 2010), which may not be accurate. In this study, depletion of total organic carbon, nitrogen and phosphorous was only 43.1, 51.3 and 50.9%, respectively. However, as polyps of G. fascicularis continue to capture prey throughout the observed period, and taking a digestion time of 3 to 6h into account (Lewis, 1982; Fabricius et al., 1995; Hii et al., 2009), collected Artemia aggregates may have represented a heterogeneous pool in terms of digestive status. Therefore, our measured nutrient depletions may reflect an average extracoelenteric feeding efficiency of G. fascicularis for Artemia nauplii. Another possible shortcoming of nutrient depletion measurements is that this method cannot distinguish between nutrients assimilated and those leaked into the surrounding environment. Therefore, tracer studies with stable isotopes, such as 13 C and 15 N, may provide even more
The phosphaterock was simultaneously solubilized by the organic acids (Vassileva et al. 2000). Indeed, the phos- phorous solubilization depends on the mode of biocatalyst applications (free or encapsulated cells) and the initial concentration of phosphaterock in the cultivated medium. Ghosal and Chakraborty (2012) examined the solubility of four sources of phosphatic fertilizers namely, triple superphosphate (TSP; 21.75% P), partially acidulated phosphaterock (PAPR; 12.97% P), Morocco phosphaterock (MORP; 14.87% P), and Mussoorie phosphaterock (MRP; 8.12% P) by six different extractants, namely 2% citric acid, 0.002 N hydrochloric acid, N-Ammonium cit- rate, Bray-2P extractant, Olsen’s extractant, and Morgan’s reagent under seven periods of incubation (1, 2, 3, 7, 10, 15, and 30 days), with and without soil. The partially acid- ulated source released P higher than phosphaterock but lower than triple superphosphate after (1–3 days) incuba- tion (1.31–1.34% with soil, 0.46% without soil) with an in- crease in the later periods (seventh day) (1.27–1.92% with soil, 0.55–0.66% without soil). The phosphate rocks re- leased maximum phosphorus after the seventh day of the incubation period. Among the different solvents used, maximum phosphorus released was observed by 2% citric acid and Olsen’ s extractants.
The second method is the horizontal comparison or the substitution rate. This is the amount of fertiliser SSP that can be substituted by PR, which is still supplying the same amount of nutrients. The substitution method is measured by the ratio of fertiliser inputs (x) that produce the same increase in yield (y). This can be explained by the equation Substitution Rate= (x2/x1)=(y1/x1) X (x2/y1) (Bolan et al., 1990) Figure 7. The measure of agronomic effectiveness is widely used throughout research on PR and it is important to have a consistent measure, which can be used to compare results between studies. Van Straaten (2006) stated that the agronomic effectiveness of rock fertilizers is a function of rock factors, mineralogy, Ca substitution, particle size and soil factors such as organic matter content, pH, texture, crop factors, environmental factors and management factors. Given all that affects agronomic effectiveness the need for one measure is important if conclusions are to be drawn between studies.
phosphates and that increases in rate pressure products result in demonstrable signs of ischemia in the myocardium which span the entire left ventricular wall. Ischemic changes include a global increase in inorganicphosphate and corresponding decreases in creatine phosphate, ATP, and pH. Importantly, changes in intracellular pH are noted with even the slightest increase in workload suggesting that these diseased hearts display elevated glycolytic activity. By challenging these animals with increased cardiac workload, we directly visualize how the chronically compromised heart responds to severe oxygen challenges in a clinically relevant model of this situation.
Aquatic environments are generally polyphases. They can be correctly described by considering the intervention of various minerals which regulate the bioavailability and the mobility of several ions. Thus, the knowledge of the interaction nature with these surfaces in aqueous solution is of great importance. Among these minerals, aluminum oxides and oxyhydroxides are abundant and can exist under numerous forms, such as Corundum (α-Al 2 O 3 ), Gibbsite (α-Al(OH) 3 ), Boehmite (γ-AlOOH) and Bayerite (β-Al(OH) 3 ) . Phosphorus is commonly found in