Plant nutrient transport

Organic fertilizers

Composed of chemically complex matter. Compost piles or bins contain organic matter broken down (decomposed) by bacteria and fungi, making nutrients available to plants.

Fertilizers

The quality of the soil - especially the availability of nutrients - determines the health of growing plant. Less nutrients cause stunted growth, lower crop yield, lower nutritional value for customer. Nutrient deficiency is treated with fertilizer: inorganic or organic fertilizer. Inorganic fertilizers (mineral fertilizers) consist of natural fertilizer or synthetic fertilizer. Natural fertilizers release nutrients gradually and are a limited resource. Synthetic fertilizers contain ammonium nitrate and other synthetically produced compounds. Organic fertilizers consist of compost and biomass.

adhesion

The sticking together of molecules of different kinds. This is water allows water to "stick" to the cell walls in xylem tissue. It is also what allows the meniscus to form on tubes. Ex. cell walls and water adhesion

cohesion

The sticking together of molecules of the same kind. For water, this is possible because of the strong hydrogen bonding forces due to its large net dipole moment. It creates a "chain" of water molecules moving up the tree.

Plant bacteria alliance

1) A plant secretes a bacteria-attracting compound from its roots. 2) Bacteria enter the roots and move to the inner cells and multiply, forming a big round nodule. 3) Plant delivers sugar to nodule, which serves as a fuel to enable bacteria to split apart N2 absorbed from soil. 4) The bacteria produce and release molecules with usuable nitrogen into the plant. 5) The plant distributes and absorbs the nitrogen throughout the plant body so that i can grow.

guard cells control transpiration

A plant must make a trade-off between its need for water and its need to make food by photosynthesis. If soil dries out and transpiration exceeds the delivery of water to leaves, the leaves will wilt and may eventually die (water is more important than photosynthesis). Leaf stomata help plants adjust their transpiration rates to changing environmental conditions. This works when water enters the guard cells via osmosis to open up the stoma. As the guard cells take up K+ cations, the stoma begins to open as osmosis takes place, allowing transpiration to occur. As the ions are released eventually, the stoma begins to close, halting the process of transpiration. Ex. Lips = guard cells, Straw = photosynthesis

essential nutrients

A plant must obtain it to complete its life cycle. Symptoms of deficiency include stunted growth and discolored leaves. There are 13 other elements a plant needs beside carbon, hydrogen and oxygen. 6 are macronutrients while 7 are micro nutrients.

Transpiration

For the most part, sap is not pushed from below but pulled upward. Loss of water from the leaves and other aerial parts of a plant by evaporation. Water is lost through the opening in the stoma. This is possible because of 2 properties: adhesion and cohesion.

Hypoxic zones

Hypoxic zones, also known as eutrophication, are the result of over-fertilization of farm soil. The leeched nitrogen enriched soil then is carried down stream river to oceanic deltas. Here, the nitrogen is manifested where algae will grow uncontrollably, blocking sunlight and taking up additional space. After which, the oxygen concentration in the water depletes and fish as well as other marine life can no longer survive.

Phloem transport chains

In angiosperms, phloem contains food-conducting cells (sieve-tube elements) arranged end to end to form long tubes. Phloem sap (sugar liquid) can move freely from one cell to the next (main solute: sucrose). Phloem sap moves throughout the plant in various directions (sieve plate regulates direction). Sieve tubes always carry sugars from sugar source (net producer of sugars) to sugar sink (net consumer or storer of sugar). Most of the time, the sugar producer is the leaf, but this is not always the case, as the root can also transport sugar to elsewhere needed. The sieve plates in the sieve tubes allow regulation of the sap/sucrose transport.

Nitrogen alternatives

Insectivorous plants use an alternative strategy to obtain nitrogen where N fixation is scarce or non-existant. For the most part, decomposition or nitrogen fixation are the 2 main methods. Ex. Venus flytrap, pitcher plant Some plant species are not able to form an alliance with nitrogen-fixing bacteria and must scavenge for usable nitrogen in the soil. It can be productive for farmers to rotate their crops every few seasons, alternating between plants that have nodules and those that don't (using legumes). Excess N fixed by bacteria become usable soil N (replenished like natural fertilizer). Parts of plants that are left in the field to decay are also a source of N for other plants ("green manure").

Organic farming

Involves agricultural practices that promote biological diversity by maintaining soil quality through natural methods. These include rotating crops (legumes rotation), planting cover crops, amending soil with organic matter, using few or no synthetic fertilizer, providing habitats for predators of pests rather than relying mainly on synthetic pesticides. The challenge is finding better natural fertilizers that increase crop yields while promoting sustainability. Our future lies in 2 goals: feeding the world's population and promoting a healthy environment in the process.

Legumes

Legumes are crops that naturally restore nitrogen and other important compounds necessary for plant growth in the soil. It makes sense to use these for crop rotations so valuable nutrients are available to the next generation of plants that don't naturally produce these compounds. Ex. Peas, beans, alfalfa, etc

Over-fertilization

Mineral nutrients N and P typically determines the amount of growth of phytoplankton (microscopic algae). "Too much of a good thing": large inputs of N and P from sewage and runoff from fertilized lawns, household cleaning products and farms (Ex. eating 2000 kcal all at once). This produces heavy growth of algae ("algal bloom"), which reduces light penetration. When algae dies and decompose, a body of water can suffer severe oxygen depletion (hypoxic conditions) from bacterial respiration. This will kill fish that are adapted to high-oxygen conditions. As a result, hypoxic zones ("dead zones") from in oceans. This is ironic since we think that over fertilizing will lead to larger food yields, which it doesn't, and actually kills a food source in the aquatic ecosystem via eutrophication. Ex. the Gulf of Mexico is a major source for the seafood industry. Consequentially, if the hypoxic zone continues or worsens, fishermen and costal state economies will be greatly impacted. It's ironic to think that over fertilization will help increase the amount of food.

Synthetic fertilizers

Nutrients are available immediently, but they may not retain in the soil for too long. Over-fertilization causes pollution of groundwater, streams, lakes, and oceans. They also contribute to greenhouse gas emission, as they often release N2O (nitrous oxide) into the atmosphere, which is very potent.

Nitrogen fixation

One of the most common nutritional deficiencies in plants is nitrogen, and it is usually what ends up limiting their growth indefinitely. The atmosphere is nearly 80% N2. To be used by plants, N2 needs to be converted to ammonium (NH4). Atmospheric nitrogen does not exist in an easily usable from in nature and must first be chemically modified by bacteria. Bacteria break apart the strong and stable bonds of atmospheric nitrogen. N is converted into NH4 or NO3 and is now usable by plants.

Pressure flow mechanism

Osmosis allows water to flow into the phloem where there is a higher concentration of sugar due to active transport. This flow of water causes pressure to build up, which allows the sugar water to be transported elsewhere in the plant. Once the water has delivered the sugar, it re-enters the xylem, conserving most of the water used in the process.

Macronutrients in plants

Plants require relatively large amounts of them. There is a large abundance of them in plants. Macro refers to its need and abundance in the plant, not its molecular size. Macronutrients: 1) Nitrogen (proteins and ATP) 2) Phosphorus (ATP, DNA, and cell membrane) 3) Magnesium (Chlorophyll) 4) Potassium (enzymes and control of water balance) 5) Sulfur (proteins and vitamins) 6) Calcium (cell wall and various functions)

Root pressure

Root cells pump inorganic ions into the xylem, and the root's endodermis holds ions there. As ions accumulate in the xylem, water tends to enter by osmosis, pushing xylem sap upward. This force can push xylem sap up a few meters via water propulsion. This processes allows the nutrients and water to first enter the plant, but transpiration is what really allows them to travel up the plant. This is more or less a weak form of nutrient transport.

compost

Soil-like mixture of organic matter that is used as soil for farming. It is produced sustainably, and serve its purpose just as well as synthetic fertilizer.