Plant nutrition sherlock holmes style

Above video on plant nutrition  problems specifically  deficiencies. It will help you be a plant detective or plant nutrition detective on  determining why you're having those deficiencies, because identifying the  deficiency is really only half of the problem........ 

 
If you find it difficult to watch above video pl watch you tube video by clicking following link
https://www.youtube.com/watch?v=AasjIXCkots

What forms the basis of nutrient mobility in soil and plants?
 
Nutrient mobility in soils can be explained on the basis of charge with most of the cations being immobile and anions being mobile except phosphorus and molybdenum which form insoluble precipitates.

Read more on nutrient mobility  


Mobile Nutrients (The first NO points to the immobile nutrients chart)

- ResearchGate. Available from: https://www.researchgate.net/post/What_forms_the_basis_of_nutrient_mobility_in_plants [accessed Nov 30, 2016].

Plant Nutrition

Plant nutrients are chemical elements that are essential for plant growth and reproduction.. For an element to be essential, it must be required for a plant to complete its life cycle, it must be required by all plants, and no other nutrient can replace this requirement fully. If an element does not meet all of these requirements,
for example, being required by some plants or only enhancing the growth of plants, the
element may be a beneficial element. Much interest in plant nutrition lies in the development and
use of diagnostic techniques for assessment of the status of plants with respect to plant nutrients and
beneficial elements.
A plant nutrient is a chemical element that is essential for plant growth  Essential
element is a term often used to identify a plant nutrient. The term nutrient implies essentiality, so it
is redundant to call these elements essential nutrients. Commonly, for an element to be a nutrient,
it must fit certain criteria. The principal criterion is that the element must be required for a plant to
complete its life cycle. The second criterion is that no other element substitutes fully for the element
being considered as a nutrient. The third criterion is that all plants require the element. All the
elements that have been identified as plant nutrients, however, do not fully meet these criteria, so,
some debate occurs regarding the standards for classifying an element as a plant nutrient. Issues
related to the identification of new nutrients are addressed below (click)

http://biology4isc.weebly.com/1-mineral-nutrition.html

http://biology4isc.weebly.com/uploads/9/0/8/0/9080078/____________how_plants_obtain_nutrients.swf

Tomato crop guide: Dynamics of nutritional requirements
 
Nitrogen and potassium uptake is initially slow but rapidly increases during the flowering stages. Potassium is peaking during fruit development, and nitrogen uptake occurs mainly after the formation of the first fruit. Phosphorus (P) and secondary nutrients, Ca and Mg, are required at a relatively constant rate, throughout the life cycle of the tomato plant.
Read more. 

Tomato crop guide: Dynamics of nutritional requirements

Why do farmers use FERTILIZERS?

Farmers use fertilizer to prime their soil for optimal plant growth. Important components of plant growth are lost when plants use them. Fertilizer restore these important elements.


The most important component of fertilizer is the nitrogen it contains. Plants need a significant amount of nitrogen to grow, and they cannot absorb it through the air. Farmers test their soil for nitrogen levels and use fertilizer with the right amount to let their plants grow as quickly as possible.
Fertilizer contains other important elements as well. Phosphorous and potassium are important for cellular function, and low levels stunt plant growth. Calcium, magnesium and sulfur are also contained in most fertilizer. Manure is sometimes used to increase the nitrogen levels of soil, but it lacks many of the other chemicals plants need.
In the wild, plants that die decompose on the ground and leave behind the elements they absorbed while they were alive. Farming, however, requires removing plants after they have grown. Soil health is an essential part of farming, and small oversights can be disastrous for farmers and for food supplies. While older farming techniques might mitigate some of the soil harm from large-scale farming, modern agriculture depends on fertilizer to prevent food shortages and famines.

What are the advantages and disadvantages of fertilizers?

Fertilizers can expedite plant growth and provide economic benefits to farmers and nurseries, but they can also introduce toxic substances into the environment. Fertilizers make plants and crops grow more quickly and appear greener, fuller and healthier. However, they often contain synthetic chemicals, which do not biodegrade upon entering surrounding waterways and the atmosphere.

Fertilizers, when used in agricultural facilities and commercial greenhouses, can significantly boost output and appeal. Fertilizers work by providing plants and crops with nutrients they need to grow to their fullest and at a faster rate than achieved through natural processes alone. Chemical-based fertilizers, according to Edublogs, can also help protect plants and vegetation from pests and may prevent the spread of weeds as well. Fertilizers may also be more cost effective and time efficient for gardeners and commercial farmers as well. Many fertilizers are inexpensive to produce, and purchasing them to encourage plant growth instead of buying high-quality soil may save significant amounts of money. However, fertilizers have disadvantages as well. One of the main concerns over fertilizers is that they require frequent reapplication. Furthermore, they contain synthetic (and often harmful) chemicals that pollute streams, lakes and the atmosphere when released. Fertilizers may cause cumulative harmful effects on humans, animals and environments, such as contaminated water supplies and spread of illness.

What are artificial fertilizers?

Artificial fertilizers are man-made chemical compounds that mimic the soil's natural minerals and elements to maximize plant growth. They usually contain different ratios of nitrogen, phosphorus, potassium, calcium, magnesium and other elements.

There are two types of fertilizers: artificial and organic. Artificial fertilizers are convenient, easy to use and readily available in local gardening stores. They immediately supply consistent amounts of precise nutrients to the soil, which is especially helpful for reviving dying or severely malnourished plants. Organic fertilizers include biofertilizers, green manure, organic manure and compost. While natural fertilizers take longer to build soil vitality, they are safer and cause no pollution.
Throughout most of history, agriculture has relied on natural fertilizers to increase the nutrient levels of soil. The release of artificial fertilizers in the late 19th century increased crop yields and launched the agricultural revolution.
Despite its advantages, artificial fertilizers kill beneficial microorganisms in the soil that convert plant and animal remains into nutrient-rich organic matter. They also leach nitrogen and phosphate into groundwater and pollute streams, rivers, lakes and other water bodies to disrupt aquatic ecosystems. Plants grown from synthetic fertilizers contain toxic nitrates that react with hemoglobin to damage the vascular and respiratory systems and cause suffocation and even death in extreme cases. Over time, artificial fertilizers destroy the soil’s natural makeup. Too much fertilizer produces plants deficient in iron, zinc, carotene, vitamin C, copper and protein.
Individuals can minimize the negative effects of artificial fertilizers by mixing them with the soil well enough to prevent rain runoff. Diluting it prevents burning plants. Synthetically grown fruits and vegetables require a thorough wash before eating. Individuals must keep unused fertilizer away from water, pets and children.

You can gain more knowledge on above topic by reading the following article (Click the title to read).

Why do farmers use fertilizers? I’ve heard that fertilizers can have negative effects. Why do farmers use fertilizers?  

  

Balanced Fertilisation and the Liebig's Law of Minimum
The importance of balanced fertilisation in increasing crop yields is recognised world-wide. Nutrient imbalance produces low yields, low fertiliser use efficiency, and low profits for farmers. It also results in further depletion of the most deficient nutrients in the soil. Once the critical level of any one plant nutrient is reached, crop yields will fall despite the fact large amounts of other nutrients are applied.
http://www.ipni.net/publication/bci.nsf/0/40B88B414D30A23885257BBA006FB94A/$FILE/Better%20Crops%20International%201998-2%20p30.pdf

The pathways of mineral transport in roots.

Minerals are absorbed at the surface of the root, mainly by the root hairs. In passing through the cortex, they must either follow the cell walls and the spaces between them or go directly through the plasma membranes and the protoplasts of the cells, passing from one cell to the next by way of the plasmodesmata. When they reach the endodermis, however, their further passage through the cell walls is blocked by the Casparian strips, and they must pass through the membrane and protoplast of an endodermal cell before they can reach the xylem.

1. a. The transportation of water molecules and mineral ions from the soil to the roots could occur   

        via several pathways such as vacuole, apoplast and symplast. Describe these three pathways.     

                                                                                                                                           [8] 
 

    b. Among the mehanisms of the translocation of sugar through sieve tubes are the mass-flow   

        hypothesis, the electro-osmosis ans the cytplasmic streaming. Describe these three       

        mechanisms.                                                                                                                [7] 

Answer:

a. - water is absosrbed mainly by root hairs which are cellular extensions of root hair cells.

   - the root hairs increase the surface area of the roots enormously.

   - dissolved substances build up in root hair cells by diffusion and active transport.

   - this accumulation of solutes gives the root hair cells a lower water potential than that of the  

     water in the soil.

   - as a result, water enters a root hair cell by osmosis, increasing its water potential above that of   

     its neighbours.

   - water is then drawn in by osmosis from root hair into the adjacent cortical cells. water moves  

     from cell to cell in the root along the water potential gradient.

   - there are three possible routes:

     i. Apoplast pathway

       - water passes freely through the cell walls from one cell to another as water is pulled up the            

         xylem due to transpirational pull, the cohesive forces between water molecules ensure that    

         water is drawn across adjacent cell walls.

   ii. Symplast pathway

       - water diffuese through the cytoplasm of adjacent cells

       - the cytoplasm of adjacent cells os interconnected by cytoplasmic strands called 

         plasmodesmata which pass through pores in the cell walls.

   iii. Vacuolar pathway

        - water moves along through the vacuoles as well as the cytoplasm

        - water has to move across the endodermis by the symplast pathway because the cell walls of   

           the endodermis are impregnated with a waterproof waxy material called suberin called   

           Casperian strip. the Casperian strip blocks the water passing along the cell walls (apoplast    

           pathway)

        - the endodermal cells actively secrete mineral salts into the xylem vessels of the root. This   

         lowers the water potential in the xylem vessels. water from the root cells is drawn into the  

         xylem by osmosis.

b. Mass-flow hypothesis

- the sucrose and other organic solutes synthesized in the leaf are actively loaded by transfer cells and companion cells into the sieve tube.

-this lowers the water potential of the solution in the sieve tubes

- as a result, water is drawn from the xylem in the leaf into the sieve tubes by osmosis.

- the entry of water produces a high hydrostatic pressure  in the sieve tube.

- in the roots, the sucrose is actively transported into the tissues for respiration, the synthesis of cell walls or changed into starch for storage.

- the water potential in the root cells decreases. Water is drawn from the sieve tube into the root cells by osmosis

- the hydrostatic pressure in the leaf is higher in the source compared to the pressure in the roots 

- this causes passive mass flow of water and solutes such as sugars, amino acids from the leaf to the roots.

Electro-osmosis mechanism (* picture refer to notes)

- the companion cells contain numerous mitochondria which generate ATP required to remove potassium ions from one side of the sieve plate into the companion cell

- the potassium ions are then secreted on the other side of the sieve plate, creating a potential gradient across the sieve plate

- this causes ab electro-osmosis flow of water molecules and dissolved solutes through the sieve pores to the adjacent sieve tube element.

Cytoplasmic streaming mechanism (* picture refer to notes)

- involves a circular movement of cytoplasm from one end of the sieve tube element to the other end.

- the solutes pass through the sieve pores by active transport 

-this helps to account for the bidirectional movements along the sieve tubes