Mineral nutrient uptake

D. T. Clarkson, Factors affecting mineral nutrient uptake by plants. Amw. Rev. Plain Physiol. 36 77 (1984). 

Chitosan and chitosan oligomer were also sprayed on the leaf of coffee in field. Chitosan and chitosan oligomer increased the content of chlorophyll, mineral nutrient uptake, and growth. 

The amount of each element required in daily dietary intake varies with the individual bioavailabihty of the mineral nutrient. BioavailabiUty depends both on body need as deterrnined by absorption and excretion patterns of the element and by general solubiUty, and on the absence of substances that may cause formation of iasoluble products, eg, calcium phosphate, Ca2(P0 2- some cases, additional requirements exist either for transport of substances or for uptake or binding. For example, calcium-binding proteias are iavolved ia calcium transport an intrinsic factor is needed for vitamin cobalt,... 

Traditionally, nutrient uptake from solution culture was taken to depend on the concentration of the external mineral nutrient, C , the amount of nutrientabsorbing surface, and the kinetics of uptake per unit surface area or unit length of root (22). The flux of nutrients into the roots, J, is described by one of two functionally equivalent equations. ... 

Table 1 Critical Root Di.stances for Three Mineral Nutrients for Different Periods of Uptake ...

Table 2 Standard Parameter Values for the Uptake of Mineral Nutrients by Maize ...

The level of plant mineral nutrients available to trees is known to affect fruit quality, but its relative effect is often overestimated compared to other factors such as fruit load and light (and associated assimilate supply to fruit) (see sections above) (for review see Neilsen and Neilsen, 2003). The mineral nutrition of trees and fruits is complex. Uptake of the macronutrients nitrogen... 

PROFILE is a biogeochemical model developed specially to calculate the influence of acid depositions on soil as a part of an ecosystem. The sets of chemical and biogeochemical reactions implemented in this model are (1) soil solution equilibrium, (2) mineral weathering, (3) nitrification and (4) nutrient uptake. Other biogeochemical processes affect soil chemistry via boundary conditions. However, there are many important physical soil processes and site conditions such as convective transport of solutes through the soil profile, the almost total absence of radial water flux (down through the soil profile) in mountain soils, the absence of radial runoff from the profile in soils with permafrost, etc., which are not implemented in the model and have to be taken into account in other ways. 

Several roles of endophytic fungi for the host plant have been postulated. These include acting to increase access to mineral nutrients (a mycorrhizal function), to increase access to organic soil N, P and C, to increase drought and stress tolerance, to improve water uptake, protection from herbivory (mammals, insects), and for protection from plant pathogenic fungi, bacteria, nematodes, and other parasites. We should not be surprised that endophytic fungi are such common plant symbioses. 

Figure 9.3. Model for the action of humic substances (HS) on plasma membrane-bound targets of a root hair cell. Besides the well-known effects on plasma membrane H+-ATPase (P) and carriers (C) of mineral nutrients, the envisaged alteration of membrane lipid environment and the possible interaction with an hypothetical membrane receptor (R) for humic molecules which allows transduction of the signal for induction and expression of genes involved in nutrient uptake and root hair development are also presented.

Phenolic acids are known to alter photosynthetic and respiration rates, cause stomatal closure, reduce chlorophyll content, modify the flow of carbon into various metabolic pools, and alter nutrient uptake in affected tissue (61-73). A common denominator for these multiple effects appears to be the action of phenolic compounds on membranes. They are soluble in membranes, and cause a reduction in ion accumulation in cells (71-73). Several phenolic acids cause membrane depolarization, especially at low pH, increasing membrane permeability to ions (72,73). This action undoubtedly impairs the proton gradient and ATP-driven ion transport. Logically, the effects phenolic acids have on membranes could disturb the water balance and mineral nutrition of seedlings, and research in my laboratory has established such a relationship. 

Fig. 10.8. Simple biogeochemical model for metal mineral transformations in the mycorhizosphere (the roles of the plant and other microorganisms contributing to the overall process are not shown). (1) Proton-promoted (proton pump, cation-anion antiport, organic anion efflux, dissociation of organic acids) and ligand-promoted (e.g. organic adds) dissolution of metal minerals. (2) Release of anionic (e.g. phosphate) nutrients and metal cations. (3) Nutrient uptake. (4) Intra- and extracellular sequestration of toxic metals biosorption, transport, compartmentation, predpitation etc. (5) Immobilization of metals as oxalates. (6) Binding of soluble metal species to soil constituents, e.g. clay minerals, metal oxides, humic substances.

This chapter reviews the distribution, mechanism and impact of mineral tunnelling by soil ectomycorrhizal fungi (EMF). Most trees in boreal forests live in close relation with EMF (Smith Read, 1997). These EMF mediate nutrient uptake they form an extension of the tree roots. In turn they obtain carbohydrates from the tree. Over the years ectomycorrhizal (EM) research has a strong focus on nutrient acquisition by EMF from organic sources (Read, 1991). In boreal forest systems, however, minerals could also be an important nutrient source, especially for calcium, potassium and phosphorus (Likens et al, 1994, 1998 Blum et al, 2002). Recent developments in EM research suppose a role for EMF in mobilizing nutrients from minerals (see Wallander, Chapter 14, this volume). 

The nutrients that the plants take from the soil to grow and produce fruit need to be replaced by replenishing the soil and by the application of fertilizers. The nutrient uptake of an apple orchard in full production is relatively low. If the yield is between 25 and 50 t/ha, the trees take up 20-30 kg N, 5-15 kg P2O5, 50-80 kg K2O, 17-20 kg CaO and 6-8 kg MgO (Greenham, 1980). The nutrients supplied by fertilizers are not fully available for use by the fruit plants, as nutrients may be lost as a result of leaching, runoff and fixation. On the other hand, nutrients are constantly being made available to the plants through mineralization and the action of weather on the soil. 

The interplay of acid-base, solubility, and complex ion equilibria is often important in natural processes, such as the weathering of minerals, the uptake of nutrients by plants, and tooth decay. For example, limestone (CaCOj) will dissolve in water made acidic by dissolved carbon dioxide ... 

Nutrient recycling and supply is tightly regulated by largely biotic processes, such as retranslocation or resorption prior to leaf abscission (Medina and Cuevas 1989, Cuevas and Medina 1990). Nutrients are also reutilized from decomposing residues through rapid mineralization and uptake by a dense... 

Most disturbances produce a pulse of nutrient availability because disturbance-induced changes in environment and litter inputs increase mineralization of dead organic matter and reduce plant biomass and nutrient uptake. Anthropogenic disturbances create a wide range of initial nutrient availabilities. Some disturbances, such as mining, can produce an initial environment that is even less favorable than most primary succes-sional habitats for initiation of succession. Some agricultural lands are abandoned to secondary succession after erosion or (in the tropics)... 

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