Plants tissue phosphorus concentrations

FIGURE 9.42 Mean plant tissue phosphorus concentration (percentage dry weight) of emergent wetland plants grown under conditions of sustained fertilization. (From McJannet et ah, 1995.)... 

Third, most of the available evidence suggests that, at a given soil P concentration, plants growing at elevated [CO2] are capable of maintaining their tissue phosphorus concentrations. This is in contrast to nitrogen and occurs because of the positive effects of larger root systems on the extent of root mycorrhizal colonization, root organic acid efflux per plant, and root acid phosphatase activity. All three processes play important roles in phosphorus acquisition. 

FIGURE 9.43 Relationship between phosphorus concentration of live tissue and litter (A, wetland plants of temperate northern wetlands [from Bedford et ah, 1999] B, Typha and Cladium from northern Everglades C, bogs and fens [from Kellog and Bridgham, 2003]). 

Plants contribute to soluble phosphorus not only after their death but also while they are still alive, as older tissues leach. Uptake of phosphorus by vegetation maintains low soluble phosphorus concentration in the soil profile. A large portion of phosphorus stored in belowground biomass is usually not accounted for in mass balance studies. Most of the emphasis is placed on aboveground... 

Note Y = mass N P ratio of the plant tissue X = soil total phosphorus concentration (mg kg ) ... 

The secoixlary nutrients are calcium, magnesium, and sulfur. Concentrations of these nutrients in plant tissues generally are lower than those of the primary nutrients (nitrogen, phosphorus, and potassium) but are higher than those of the micronutrients. The seven micronutri-ents are boron, chlorine, copper, iron, manganese, molybdenum, and zinc, Because chlorine deficiencies rarely occur in nature, most discussions on supplying micronutrient fertilizers are confined to the other six micronutrients. 

The content of crude protein, fat, carotene and AA in the dry matter markedly increased on application of nitrogen (N) especially in quantities of 100 and 150 mg/kg soil (Filimonov, 1969). Largskii (1971) showed that doses of N above 60 mg/kg soil maintained the amount of total sugar and AA in the cucumber. Phosphate fertilizer increased the concentration of these substances. Sugar content and dry matter were also Increased by the fertilizer. An increase in the phosphorus level also enhanced the sugar and AA concentrations and decreased the nitrogen content in plant tissues, especially under water deficit ... 

Increase of phosphorus level Increased sugar and AA concentration and decreased the nitrogen content In plant tissues, especially under water deficit (Popovskaya, 1957). AA content was found to be Inversely related to the nitrogen concentration and the amount of water In the plant tissues ... 

Since plants and animals are able to concentrate phosphorus in their tissues, and since these tissues contain their own reducing agents, E. B. R. Prideaux does not consider it surprising that physicians and pharmacists of the seventeenth and eighteenth centuries first prepared this element from substances of vegetable and animal origm (36). 

The method involving the Mo-V-P acid has been used in determinations of phosphorus in biological tissues [127], plant material [128], fruits [129], fish products [130], foodstuffs [131], phosphate minerals [132], cast iron and steel [133,134], niobium, zirconium and its alloys, titanium and tungsten, aluminium, copper, and white metal [135], nickel alloys [134,135], metallurgy products [136], molybdenum concentrates [137], silicon tetrachloride [7], cement [138], and lubricants[139]. The flow injection technique has been applied for determining phosphate in minerals [140] and in plant materials [141]. 

McJannet, C. L., P. A. Keddy, and F. R. Pick. 1995. Nitrogen and phosphorus tissue concentrations in 41 wetland plants a comparison across habitats and functional groups. Funct. Ecol. 9 231-238. 

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