Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Plant bio
Phosphorus
| Question | Answer |
|---|---|
| Phosphorus | - P has roles in cell structure, energy and information storage and energy and information transfer - 1st or 2nd most commonly limiting nutrient for plant growth - essential nutrient found in many biomolecules ie. DNA/teeth - rare macronutrient |
| Global phosphorus cycle | - no atmospheric phosphorus - weathering of P from rocks to soil - terrestrial cycle (plants, animal, soil) - leaching of P into bodies of water |
| Human influence on phosphorus cycle | - mining and commercial processing - increased sewage and runoff to bodies of water, increasing algal blooms (toxic) - modern practices accelerate runoff |
| Phosphorus in soil | - found in form of insoluble complexes - plants can't take up organic phosphate - depletion zone: only P close to roots is taken up |
| Phosphate use in agriculture | - consumption of P majorly increased due to population increase - crops only take up 50-70% applied P fertiliser - overuse was common, but now N:P ratio is 1:6 (better) |
| pH | - phosphate availability varies with pH - optimum soil pH is 6 for available phosphates |
| Eutrophication | - increased biomass production (leads to algal blooms) - decreased O2 concentrations - ecosystem collapse |
| Consequences of P limitation | - sufficient P: green leaves (chlorophyll) - low P: darker/red leaves (lacks chlorophyll) |
| Phosphate uptake systems: root structure | - nutrient accumulation requires uptake across plasma membranes - PMs of root cells are selective and determine what enters the shoot |
| Plant phosphate transporters | - Pht proteins: localised to PM and uptake at root - co transporters acquire Pi from rhizosphere (soil) - Pht2&3 localised to organelles (chloroplast/mitochondria) - Pht1 mediate uptake and transport |
| Rhizosphere pt.1 | - plants engineer their rhizosphere - root exudes, organic acids and proteins - many species respond to nutrient deficiency - low pH helps solubilise these nutrients |
| Rhizosphere pt.2 | - carboxylates complex to metal ions that bind to phosphate by ligand exchange - H+ secretion can balance charge |
| Acid phosphates | - promote uptake of organic P In response to P deficiency the roots of many species secrete acid phosphatases, which solubilise Pi from organic P-esters |
| Root system architecture | root traits associated with enhanced phosphate uptake: - reduced gravitropism (roots slump) - formation/elongation of roots - aerenchyma (air spaces allowing metabolically inexpensive growth |
| P deficiency | - influences rooting depth and branches pattern - low P causes shallow roots, attempting to find higher P concentrations in the soil: root foraging - increased density and length |
| Root hairs | - projections of trichoblast cells - increases root surface area - increase the volume of nutrient depletion zone |
| Symbioses: AM fungi | - plants use AM fungi network to increase the effective reach of the roots - facilitates P uptake in most plants AM: 450+ MYA symbioses, surrogate roots for first land plants, main role thought to be P uptake |
| AM and role in P exchange | - plant releases strigolactones, that affects hyphal growth - fungi enters the plant, forming a branched structure (arbuscule) - sites of exchange from sugars to nutrients - data suggests Pi is translocated through fungal hyphae as polyphosphate |
| PT4 | - located on the periarbuscular membrane, a phosphate transporter |
| Legume symbiosis | - legumes can form symbioses with AM fungi and legume-Rhizobium - many similarities between the two |
Created by:
rose.coo
Popular Ecology sets