The bacteria-soil-plant interaction has been used in order to support plant nutrients and antimicrobial agents, which are selective and inhibit. plant development and growth and to help realise their relationship giving plants optimum conditions for Soil plant interactions in nutrient uptake. SOIL AIR. SOIL AND PLANT RELATIONSHIPS ASSOCIATED WITH. IRON DEFICIENCY WITH EMPHASIS ON NUTRIENT INTERACTIONS. KEYWORDS: Iron chlorosis.
Genetically modifying plants to excrete microbial phytase eg. Exudation of phosphatases increases when plants are P deficient eg. Radersma and Grierson, When grown in an acidic P-deficient soil amended with Fe-P, the P-efficient Triticum aestivum genotype had a greater acid phosphatase activity in the rhizosphere than the inefficient genotype, with phosphatase activity correlating positively with growth and P uptake Marschner et al.
Rhizosphere microorganisms and nutrient availability Root exudates are good nutrient source for microorganisms, allowing some microbial species, especially those with high growth rates and relatively high nutrient requirements such as pseudomonads Marilley and Aragno,to proliferate rapidly in the rhizosphere.
The amount and composition of root exudates affect microbial community composition which in turn will influence nutrient availability. Plants grown with deficient vs. Nutrient deficiency can influence rhizosphere microorganisms either directly by affecting their nutrition or indirectly via altering root morphology and exudation Rengel and Marschner, In addition, rhizosphere soil of different plant species shows differential composition and abundance of microbial populations eg.
Ponmurugan and Gopi, However, roots may maintain distinct rhizosphere microbial communities even when intermingling with roots of other species Wang et al.
Microbial community composition is influenced by soil properties as well as P addition Marschner et al. Differential structure of microbial communities was also noted for different plant genotypes and different growth stages Marschner et al. For example, the microbial community composition in the rhizosphere of the native Australian grass Austrostipa differed significantly from that of the two wheat genotypes, and was characterised by a high abundance of the fungal fatty acid Genotypic differences in the rhizosphere microbial community composition may possibly be due to differences in root exudation chemical type and the amount.
Indeed, it has been shown recently that organic acid anions in the Lupinus albus cluster root exudates can affect soil microbial community composition in the rhizosphere Marschner et al.
However, these relationships were dependent on soil properties, especially pH Solaiman et al. In the acidic soil, while the microbial community composition in the rhizosphere of wheat differed from that in Brassicas Wang et al.
Many microbial species have the capacity to solubilise sparingly soluble P in vitro Rengel and Marschner, ; White law, Phytate- and phosphate-solubilising bacteria have been identified, with the genus Pseudomonas being one of the most studied P-solubilising bacteria eg. About half of culturable rhizobacteria associated with perennial ryegrass, white clover, oat and wheat were capable of solubilising P-containing compounds. The rhizosphere of pasture plants perennial ryegrass and white clover contained predominantly Na-phytate solubilisers, whereas in the rhizosphere of crops oat and wheat bacteria solubilising Ca-phosphate were more prevalent than those solubilising Na-phytate Jorquera et al.
An effective interaction between P solubilisers and plants depends on i high population of P solubilisers maintained in the rhizosphere over long periods, ii exudation of carboxylates and protons into the rhizosphere by roots and microorganisms, iii low P uptake by microorganisms, and iv positive interaction with mycorrhizal fungi or other beneficial microorganisms.
P-solubilising bacteria could potentially be used as biofertilizers see the references in Deubel and Merbach, ; Jorquera et al.
CSA-20306 Soil-Plant Relations
However, large-scale inoculation with P solubilisers in farming practice is hampered by several factors that could diminish effectiveness of the introduced microorganisms: It is of utmost importance that the possible contribution of P-solubilising microorganisms to crop P uptake be evaluated in realistic soil conditions in the field cf.
Manganese availability in the rhizosphere Yield of crops and pastures on calcareous soils is frequently limited by Mn deficiency caused by low Mn availability, rather than low Mn content in soil Rengel The available Mn concentration was up to two orders of magnitude greater in the rhizosphere of three Banksia species B.
An addition of ug Mn02 g-1 soil before incubation doubled the available Mn concentration to 4 ug Mn g-1 soil. After 7 days incubation, the concentration of available Mn increased more than fold, indicating active populations of Mn reducers P. Medicago sativa plants exude a variety of carboxylates under Mn deficiency.
The amounts of exuded citrate and malonate and to a lesser extent fumarate, malate, oxalate and lactate under Mn deficiency were positively correlated with Mn efficiency of M. Manganese availability is increased in acidic rhizosphere. However, the form of N supplied, and therefore differences in rhizosphere acidification, had no effect on differential expression of Mn efficiency among Hordeum vulgare genotypes see Rengel grown in calcareous soils.
Strong pH buffering capacity of calcareous soils may contribute to preventing differential expression of Mn efficiency eg. Reduction and oxidation of Mn by microorganisms are important components of Mn cycling in soil. Fluorescent pseudomonads are effective Mn reducers, which appear to be more abundant in the rhizosphere of some Mn-efficient compared with Mn-inefficient Triticum aestivum genotypes Rengel et al. The bacterial communities in the Triticum aestivum rhizosphere were correlated with the concentration of DTPA-extractable Mn in the rhizosphere, shoot dry matter and Mn content Marschner et al.
Future work More research into understanding the basis of qualitative and quantitative differences in root exudation is required. Given that exudation of organic compounds represents a big drain of energy and resources, thorough understanding of the regulation of the whole sequence of processes culminating in exudation of organic compounds into the rhizosphere is required before practical applications become feasible.
Bioengineering the rhizosphere by adding beneficial microorganisms will require understanding of microbe-microbe and microbe-plant interactions enabling introduced microorganisms to show full activity in the targeted rhizosphere.
Effect of Boron on the Behavior of Nutrients in Soil-Plant Systems-A Review
Availability of organic and inorganic forms of phosphorus to lupins Lupinus spp. E and Rengel Z. Biology and chemistry of nutrient availability in the rhizosphere. In Mineral Nutrition of Crops: Food Products Press, New York. Influence of microorganisms on phosphorus bioavailability in soils. In Microorganisms in Soils: Springer, Berlin Heidelberg, N. Root-released organic acids and phosphorus uptake of two barley cultivars in laboratory and field experiments.
A root hairless barley mutant for elucidating genetic of root hairs and phosphorus uptake. Expression of a fungal phytase gene in Nicotiana tabacum improves phosphorus nutrition of plants grown in amended soils. Plant Biotechnology Journal 3: Genotypes of lucerne Medicago sativa L. Role of soil microorganisms in improving P nutrition of plants. Solubilization of rock phosphate by rape. Local root exudation of organic acids as a response to P starvation.
Phosphate Rock, Statistics and Information. Plant and mycorrhizal regulation of rhizodeposition. Isolation of culturable phosphobacteria with both phytate-mineralization and phosphate-solubilization activity from the rhizosphere of plants grown in a volcanic soil. Moreover, they suggested that B is involved in the physiological processes controlling the uptake and transport of Fe, Mn and Zn. Lombin and Bates found that with increasing B levels the uptake of K, Mn, Zn, Cu, Mo and B increased by alfalfa, peanut and soybean crops but had no apparent effect on the uptake of Ca and Mg in all crops.
Similar detrimental effect of B on the uptake of Ca and Mg was reported by Singh and Singh they observed varying B levels significantly increased the concentrations of N, P, K, Na and B and decreased the Ca and Mg concentration in lentil plants. On the other hand, the uptake of N, P, Na and B by grain and straw significantly increased, whilst K uptake remained unaffected with an increase in B application. Francois reported that with increasing soil solution B the concentration of B, P, K and Mg tended to increase in tomato leaf, while Ca and Na showed inconsistent trend.
After two years Francois again demonstrated the effect of B on chemical composition of radish, using sand culture technique. He found that Ca and P concentrations decreased significantly and K, Mg and Na remained unchanged with increasing B levels in the substrate.
Morsey and Taha reported that applied soil B and foliar application increased the concentration and uptake of N, P, K, Mn and B in both tops and roots of sugar plants. It is interesting, they proposed the mechanism for some nutrients in relation to B effect.
For example, B increased N uptake and could be responsible for a favorable effect on nodulation. A positive effect of B on P uptake, which altered the permeability of plasmalemma at the root surface, resulted in increase P absorption. Uptake of K increased because of their mutual synergistic relationship, but Ca decreased due to antagonistic effect. Uptake of Fe and Cu were positively correlated, while Mn and Zn negatively correlated with applied B.
Similarly, El-Fattah and Agwah observed the tip burn percentage was negatively correlated with Ca and positively with N, P, K, Fe and Cu concentrations in the leaves of lettuce. On the other hand, excess B increased the concentration of nutrients with greater significance for K, Mg and Fe, followed by Ca and Mn and in smaller quantity Cu and Zn. Nable observed that B toxicity had no consistent effects on the tissue concentration of P, K, Ca, Mg, Zn, Cu, Fe and Mn of five barley and six wheat cultivars grown in nutrient solution and no interactions were found among B, nutrients and cultivars.
In the same year Pal et al. They concluded that high levels of applied B had an antagonistic effect on the uptake of nutrients and this could be due to the toxic effects of B on root cells, resulting in an impaired nutrient absorption process. Alvarez-Tinaut found positive correlations between B and Fe and Cu contents of sunflower, suggested that B could indirectly affect catalase activity via Fe and Cu.
Positive correlation between Zn and B also indicate that B could indirectly affect the enzyme through modification of the Zn content. Tyksinski reported the antagonism between B and Zn, Cu and Mo and synergism between B and Mn, Fe in lettuce leaves, grown under differential micronutrients fertilization.The Rhizosphere: an interaction between plant roots and soil biology
Tariq reported that the concentration, total uptake and ratios of certain nutrients in radish tops and roots were considerably changed with differential B supply to nutrient solution. However, his study also suggested that the changes occurred in the nutrients response were mainly due to B effect and partly due to antagonism between Ca and B. It is clear from the reported literature review that B interactions, either synergism or an antagonism, can affect plant nutrition under both deficiency and toxicity conditions.
There are clear differences observed and contradictions in plant nutrient response with regard to B supply, which must be due to the use of different growth media, crop species and varieties and environmental conditions.
Therefore, one might expect that the effect of B on the nutrient elements to be very complex apart from few elements which need further detail investigations. Functional relationship with other plant nutrients: Beside the general functions of B, it is important to review the functions of B in relation to other plant nutrients.
Lal and Rao stated that a physiological effect of B is as a carrier of essential elements. A brief description of some elements which have functional relations to B are as follows. Similarly, Shen et al. The evidence suggested that B functions in the regulation of plant membranes and that the ATPase is a possible component of transport processes.
The possible mechanisms, whereby this control is exercised, include direct interaction of B with polyhydroxy components of the membrane and the elevation of endogenous levels of auxins. Shorrocks reported that effects of B and membrane permeability could lead to association between B and K.
The stimulation of K accumulation by the ATPase proton pump which may account for positive correlations between K and B. Regarding the similarity of B functions to other plant nutrients, Ca-B relationship is out standing. Both elements play an important role in cell wall metabolism and are required for auxin transport process Dela-Fuente et al. Boron deficiency induces abnormal changes in the metabolism of the cell wall.
However, in tomato B deficiency slightly increased Ca uptake but inhibited Ca translocation to the upper leaves Yamauchi et al. Boron tends to keep Ca in a soluble form within the plant: The results of Ramon et al. It is well known that the toxic effects of B may be reduced or prevented by adding Ca to soils.
These phenomena have been ascribed both to reactions with in soil and to metabolic processes in plants Kabata-Pendias and Pendias, Literature indicated that B functions are different from other metabolic micronutrients, but there is some evidence that B may be involved in the enzymatic activity of plants. Brown reported that B stressed plants had a higher ascorbic acid oxidase activity than B sufficient plants.
Similarly Adams et al. Leece reported that B deficiency rendered Zn inactive in maize plant, possibly due to the accumulation of IAA excess some form of feedback inhibition along its pathway of synthesis, which in turn leads to maize inactivation in some unspecified manner. Pilipenko and Solovieva also observed that Zn uptake was decreased in B deficient navy bean plants.
The distribution of Zn in different organs corresponded to the ATPase activity localized in cell walls of roots and stems. It appears that B may be concerned with the oxidation-reduction equilibria in cells Wallace, The early work of Cook and Millar showed that in the absence of B possibly Fe became fixed in the different parts of sugar beet and spinach plants as relatively insoluble and non-movable forms, perhaps as ferric ion.
The evidence indicates that B may be involved in changing the valence of Fe. In general, B functions in relation to other plant nutrients has led to the conclusion of some investigators Tanada, and Mozafar, that B plays a role in the integrity and function of plant membranes.
However, the information regarding the physiological relationships of B with certain plant nutrients such as Mg, Na and Mn is very scarce. It is evident from the literature that the supply and uptake of B brings a shift in the internal physiological balance amongst certain nutrients, which result in secondary changes and alteration in the absorption and accumulation of other ions. For example, the out standing interactions of P-Mg and Ca-Mg in tomato plants were caused by varying B supply in a sand culture study conducted by Parks et al.
They suggest that B may be a component of one or more interactions or that complex interactions involving more than two elements may exists.
Their statement suggests that B is involved in the interaction of other plant nutrients, although the nature and mechanisms of these interactions are not very clear. Ohki reported that the concentration of Mn in leaf blade of cotton was increased with low and high B in the substrate, while the concentrations of Cu, Fe and Zn drastically reduced due to the interaction of Mn with these micronutrients. Oyewole and Aduayi found negative and non-significant correlations between leaf N and Ca, leaf Mg and Ca, leaf P and Ca and leaf K and Ca and concluded that these relationships were obtained when leaf N and P decreased and leaf K, Ca, Mg and Na increased with increasing B levels in soil.
It can be concluded from the literature review that B play a role in the nutrient interactions within plant, but it is still not clear whether B is directly or indirectly involved in the interaction of certain nutrients, however the nature of these complex interactions are still obscure.
In the literature some evidence suggests that B effects are related to all the cation and anion values in the plants.