day twenty-one 22april 2015

HAPPY EARTH DAY !!!

WEATHER

baro: 1028.3 hPa | rain 0.0 mm | soil temp temp high 18.6oC low 12.3oC | wind SE 10.6 km/h , slight breeze | humidity 91% cloud partly cloudy 275 m

soil temperature 15.5oC

 

 

for the next three days we will be spending our days with our tutor BRYCE learning how to “MAINTAIN AN IRRIGATION SYSTEM USED IN HORTICULTURE”

reasons for watering plants are

– photosynthesis
– uptake of nutrients through root system
– turgidity
– osmosis

photosynthesis source 'google' sactree.com

photosynthesis
source ‘google’ sactree.com

All living things need energy to survive. Animals have to hunt or gather food to get the energy they need, but plants can make their own food using light energy from the sun. This process is called photosynthesis, and it takes place in the chloroplasts, tiny green structures found in the green parts of plants.

It is a complicated process, but basically, carbon dioxide and water are converted to glucose (a simple sugar) and oxygen.

In this way, plants make, or produce, the beginnings of most of the food energy on Earth. This is why plants are called producers. They use some of the food energy to carry out their own functions, and store the rest of the energy in their leaves, stems, roots and other parts.

When an animal eats part of a plant, the animal takes the plant’s stored food energy into its body. Creatures that eat food energy are called consumers. Animals that eat plants directly are called primary consumers. Animals that get their food energy by eating other animals are called secondary consumers since the plant’s energy has been consumed a second time. The relationships between producers and consumers can be represented by food chains and webs.

Eventually, all living things die. Then it is time for the decomposers to use the energy. Decomposers break down and take the energy from dead things into their bodies. They also enrich the soil, which helps plants to grow and create more food energy for all of us.

turgidity source: google images

turgidity
source: google images

Turgor pressure pushes the plasma membrane against the cell wall of plant, bacteria, and fungi cells as well as those protist cells which have cell walls.

This pressure, turgidity, is caused by the osmotic flow of water from an area of low solute concentration outside of the cell into the cell’s vacuole, which has a higher solute concentration. Healthy plant cells are turgid and plants rely on turgidity to maintain rigidity. In contrast, this phenomenon is not observed in animal cells which have no cell walls to prevent them from being burst by the flow of water into the cell and must either continually pump out water, with a contractile vacuole, or live in an isotonic solution where there is no osmotic pressure.

Mechanism[edit]

Turgor pressure on plant cells diagram.svg

A physical phenomenon known as osmosis causes water to flow from an area of low solute, high water concentration to an area of high solute, low water concentration, until the two areas have an equal ratio of solute to water. Normally, the solute diffuses toward equilibrium as well; however, all cells are surrounded by a lipid bilayer cell membrane which permits the flow of water in and out of the cell but restricts the flow of solute under many circumstances. As a result, when a cell is placed in a hypotonic solution, water rushes into the membrane, increasing the cell’s volume.

Eventually, the cell’s membrane is enlarged such that it pushes against the cell’s rigid wall. At this point the cell is said to be turgid.[1] In an isotonic solution, water flows into the cell at the same rate it flows out. The pressure pushing the cell’s membrane against its wall is reduced and the cell is said to be ‘flaccid’. When a cell is placed in a hypertonic solution water actually flows out of the cell into the surrounding solution. This, plasmolysis, causes the membrane to recede from the wall and is responsible for wilting in plant cells.

osmosis  source :wikipedia

osmosis
source :wikipedia

Osmosis is the spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.[1][2][3] It may also be used to describe a physical process in which any solvent moves across a semipermeable membrane (permeable to the solvent, but not the solute) separating two solutions of different concentrations.[4][5] Osmosis can be made to do work.[6]

One frame of a computer simulation of osmosis

The osmotic pressure is defined to be the minimum pressure required to maintain an equilibrium, with no net movement of solvent. Osmotic pressure is a colligative property, meaning that the osmotic pressure depends on the molar concentration of the solute but not on its identity.

Osmosis is a vital process in biological systems, as biological membranes are semipermeable. In general, these membranes are impermeable to large and polar molecules, such as ionsproteins, and polysaccharides, while being permeable to non-polar and/or hydrophobic molecules like lipids as well as to small molecules like oxygen, carbon dioxide, nitrogen, and nitric oxide. Permeability depends on solubility, charge, or chemistry, as well as solute size. Water molecules travel through the plasma membrane, tonoplast membrane (vacuole) or protoplast by diffusing across the phospholipid bilayer via aquaporins (small transmembrane proteins similar to those responsible for facilitated diffusion and ion channels). Osmosis provides the primary means by which water is transported into and out of cells. The turgor pressure of a cell is largely maintained by osmosis across the cell membrane between the cell interior and its relatively hypotonic environment.

Jean-Antoine Nollet first documented observation of osmosis in 1748.[7] The word “osmosis” descends from the words “endosmose” and “exosmose”, which were coined by French physician René Joachim Henri Dutrochet (1776–1847) from the Greek words ένδον (endon : within), έξο (exo : outside), and ωσμος (osmos : push, impulsion).[8]

WATER in Maori Culture

Waiora  Purest Water

Wai Maori is freshwater or drinking water from spring

Waimate or Waikura is stagnant water or polluted water

expressing the unseen  source www.architecturevictorious.ac.nz

expressing the unseen
source http://www.architecturevictorious.ac.nz

 

 

WATER TENSIOMETER

Tensiometer:

The tensiometer uses a column of water attached to a ceramic cup. There is a pressure gauge that is a the top of the column to measure how much of a vaccum is created. How the tensiometer works is very simple. If the soil is at field capacity then no water will be lost through the ceramic cup. But if the soil is lower then field capacity water will slowly seep out of the cup. As the water leaves the ceramic cup it causes a vaccum in the column which causes the gauge to get a reading. By taking a reading from the gauge you can figure out how much water is actually in the soil. This picture shows how depth of the Tensiometer can have an effect on the amount of water that is lost.

source : ndsu.edu

source : ndsu.edu

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