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Plant Nutrition

Plant Nutrition


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Alfie has two plants, A and B. He used some Vaseline to coat the top of the leaves on plant A and the underside of the leaves on plant B. He left the plants on the windowsill for a week and watered them regularly.

a) What do you expect happened to each plant? Plant A: __________________________________ Plant B: __________________________________

b) Explain the result you have predicted for plant B


I think plant A would use a moderate amount of water and would use the least amount of water. I think plant B would use the least amounts because coating the lower surface causes the water loss similar to coating both surfaces (upper and lower).

What are your thoughts on this?


I would try to think about the vaseline layer as a huge cuticle that our man "Alfie" just applied to the plants.

I think you have the right answer here. Just note that there is a typo in the first sentence of your thoughts. You missed a "B" in front of "plant". Took me a bit to understand.


Plant Nutrition

Green plants, unlike animals, are able to manufacture their major organic constituents entirely from inorganic raw materials that are obtained from soil, water, or atmosphere using energy provided by photosynthesis. Of over fifty elements found in plant tissues, only sixteen are considered essential nutrients for all plants. Of these sixteen, nine are macronutrients, and seven are micronutrients. Macronutrients are required in high amounts and each is present at levels of greater than 0.2 percent of plant dry weight. Most macronutrients are important constituents of organic molecules, and most have more than one role. Micronutrients are required in small amounts often have special purposes. The seven known micronutrients each make up less than 0.1 percent of plant dry weight. A few other elements (nickel, silicon, and sodium) are considered essential only for some plants. Soybeans require nickel horsetails require silicon C4 and CAM plants require sodium.

Essential Elements for Proper Plant Nutrition: Roles, Available Forms, and Deficiency Symptoms
Essential Element* Role Symbol Form absorbed Deficiency symptoms Leaves affected
Macronutrients
Hydrogen Component of organic compounds and water chemiosmotic synthesis of ATP in mitochondria and chloroplasts H H2O    
Carbon Component of organic compounds C CO2    
Oxygen Component of organic compounds and water electron acceptor in respiration O H2O    
Nitrogen nucleic acids, some hormones, and nucleic acids, some hormones, and chlorophyll N NO3–, NH4+ Plants stunted foliage light green, roots long and slender Old
Potassium Enzyme activator, involved in starch formation regulates osmotic balance and movement of guard cells K K+ Stems slender, numerous small necrotic spots form near the margins of leaves Old
Calcium Component of middle lamella (Capectate) controls activity of many enzymes maintains membrane integrity 2nd messenger Ca Ca2+ Plants stunted terminal bud dies young leaves hooked root tips die Young
Magnesium Component of chlorophyll component of middle lamella (Mg-pectate) activates many enzymes Mg Mg2+ Leaves with chlorotic spots tips and margins of leaves turned upward Old
Phosphorus Component of nucleic acids, phospholipids, coenzymes involved in sugar metabolism P H2PO4–HPO4 2- Plants stunted, foliage purple/dark green Whole plant affected
Sulphur Components of the amino acids cysteine and methionine component of coenzyme A S SO42– Young leaves light green, no necrosis Young
Micronutrients
Chlorine Involved in water balance possibly involved in photosynthetic reactions in which O2 is released Cl Cl– Leaves wilted, chlorotic, ultimately necrotic roots thickened Whole plant affected
Iron Component of cytochromes ferredoxin and nitrogenase cofactor of peroxidase involved in chlorophyll synthesis Fe Fe2+, Fe3+ Stunted growth interveinal chlorosis of young leaves Young
Boron May be involved in sugar transport regulates enzyme function B H2BO4 Terminal bud dies leaves may be twisted, base of young leaves chlorotic root tips discolored Young
Manganese Activator of enzymes involved in electron transfer, chlorophyll synthesis, and the photosynthetic evolution of O2 Mn Mn2+ Interveinal necrosis of young leaves Young
Zinc Activates many enzymes involved in the formation of pollen Zn Zn2+ Stems with short internodes leaves thick leaf margins distorted Old
Copper Component of plastocyanin present in lignin of xylem elements activates enzymes Cu Cu+, Cu2+ Young leaves permanently wilted foliage dark green terminal branches unable to stand erect Young
Molybdenum Involved in nitrogen reduction Mo MoO42- Young leaves twisted, chlorotic Young
* Elements are listed in order of decreasing number of atoms relative to molybdenum.

For an element to be considered an essential nutrient, it must meet the following three criteria: (1) The element must be necessary for normal plant development through a complete life cycle (2) no other element can substitute for that element and (3) the element must play a role in metabolism within the plant. Studies to demonstrate whether an element is essential are often very difficult to conduct. Special hydroponic culture in growth chambers that eliminate contamination from the air allows scientists to eliminate a particular element and determine plant response to the deficiency.


Plant Nutrition & Transport

Cohesion is the connection made between identical molecules, while adhesion is the connection between different ones.

Explanation:

Water molecules have cohesion forces attracting them to each other due to the hydrogen bonds they have.
When water molecules come in contact with some charge surfaces like glass or the lining of a xylem vessel, they stick to it by the adhesion forces .

Because of the charge on the surface, the water molecules are attracted to the other upper part of the surface where there is no water sticking to it. As a result, water molecules climb up a little.
These water molecules are still connected to other water molecules below them by the hydrogen bond (adhesion) and hence tend to pull them up as well. The process repeats till a water column goes up inside the tube.

This process is limited by the diameter of the tube as the bigger the diameter the smaller the water column that can climb up. The reason is that the bigger the column, the more water molecule that are to be pulled up and hence the more the effect of the gravity which is opposite in direction to the capillary action.

Transport of water and minerals absorbed by roots from the soil and organic food synthesized in green leaves are two main examples of plant transport.

Plant transport is mainly of 2 types:
1. Transport of water and minerals absorbed by rots from the soil.
2. Transport of organic food materials synthesized in green pars of the plant, mainly leaves.

  1. Transport of water and minerals- Water is absorbed from the soil by roots mainly in root hair zone. Minerals, present dissolved in water in soil, are absorbed by the roots mainly in meristematic zone.

The mechanism of absorption of water is different from that of minerals. Water is absorbed by passive mechanism whereas the minerals are absorbed by active mechanism.

Water and minerals absorbed by the root are transported to different parts of the plant through xylem.

  1. Transport of organic food- Leaves containing chlorophyll are the main sites of synthesis of
    simple carbohydrates during photosynthesis. The carbohydrates synthesized in leaves and
    other green tissues are transported to roots and other non-green parts of the plant through
    phloem.


4. Plant Nutrition

A) Between regions A and B, an increase in the brightness of light increases the rate of photosynthesis.

B) This indicates that the speed at which photosynthesis is taking place is limited by the amount of light available.

C) At higher light intensities (i.e. after point C) a further increase in light intensity would not increase the rate of photosynthesis.

D) This implies that the photosynthetic process is receiving the maximum amount of light it can make use of.

E) Hence, an increase in light intensity will not increase the rate.

Fig.4.2 Effect of temperature on the rate of photosynthesis

A) At low temperature, photosynthesis is inactive.

B) As the temperature increase, the rate of photosynthesis also increase.

C) At optimum temperature, photosynthesis is in its most active state.

D) Above optimum temperature, the rate of photosynthesis decreases.

E) At extreme temperature, photosynthesis stops, because the enzymes involved in this process are denatured.

Since photosynthesis can be affected negatively by heat, enzymes must be involved.

A) As there are more CO2, the faster the rate of photosynthesis.

B) CO2 concentration cannot exceed 0.03%, because that is the amount of CO2 in the air.

C) It can only exceed 0.03% under experimental conditions.

4 . Importance of photosynthesis:

  • It reduces the amount of CO2 in the air which is the main cause of global warming.
  • It produces oxygen to support other organisms for doing respiration.
  • It produces food which is the source of energy of other organism and itself

Fig.4.3 The external structure of a leaf

Fig.4.4 The internal structure of a leaf

6 . The important features about leaves:

  • The cells in the palisade layer are packed with chloroplasts which contain lots of chlorophyll. This is where the photosynthesis goes on.
  • The palisade and spongy layers are full of air spaces to allow CO2 to reach the palisade cells.
  • The cells in the epidermis make wax which covers the leaf structures, especially the top surface. This is to prevent water loss.
  • The lower surface is full of biddy little holes called stomata. They are there to let CO2 in. They also allow water to escape -this is how the transpiration stream comes about.
  • Xylem and phloem vessels cover the whole leaf like tiny “veins”, to deliver water to every part of the leaf and then to take away the food produced by the leaf.
  • Stomata closes automatically when supplies of water from the roots start to dry up.
  • The guard cells control this. When water is scarce, they become flaccid, and they change shape, which closes the stomatal pores.
  • This prevents any more water being lost, but also stops CO2 getting in, so the photosynthesis stops as well.

4.2 Plant Mineral Nutrition
1 . Nitrogen:Plants need nitrogen to make proteins. They got nitrogen from the compounds of nitrogen from the soil. •


Plant nitrogen nutrition: sensing and signaling

Root nitrate sensing is affected by rhizosphere pH and water availability.

Nitrate transporters are involved in sensing cellular pH changes.

Root derived small mobile peptides act as long-distance N signaling.

Shoot derived HY5 acts as a mobile signal coordinating C/N balance.

In response to external fluctuations of nitrogen (N) supplies, plants can activate complex regulatory networks for optimizing N uptake and utilization. In this review, we highlight novel N-responsive sensors, transporters, and signaling molecules recently identified in the dicot Arabidopsis and the monocot rice, and discuss their potential roles in N sensing and signaling. Furthermore, over the last couple of years, N sensing has been shown to be affected by multiple external factors, which act as local signals to trigger systemic signaling coordinated by long-distance mobile signals. Understanding of this complex regulatory network provides a foundation for the development of novel strategies to increase the root N acquisition efficiency under varying N conditions for crop production.


Experiments on Mineral Nutrition in Plants | Botany

On the basis of various experimental observations it has been noticed that a number of mineral elements are necessary for plant growth and development. They are called “essential elements”.

Again, various essential elements are required by the plants in different amounts: some are required in large quantities while others are required in small quantities — the former are designated as macro or major, and the latter as micro or trace elements.

Among approximately 40 essential mineral elements, nine elements like N, P, K, C, H, O, Ca, Mg, S are macro elements, while others like Fe, Mn, Zn, Cu, Ni, Bo, Co, Al, Vd, Na etc. are micro elements.

Each and every essential elements has its characteristic physiological functions. Deficiency of any such element produces their characteristic deficiency symptoms.

By nutrient culture (sand or water cul­ture) techniques it is possible to study the deficiency symptom of essential elements without much difficulty. The deficiency symptoms are expressed principally in leaves as characteristic foliar changes.

(A) Water Culture Technique:

1. Inorganic nutrient solution (any one)

(ii) Hoagland solution (1920)

2. Wide-mouthed bottles with cork

1. Take a few wide-mouthed bottles and fill them with the nutrient solutions of desired types. In each bottle a specific element is lacking except the control one. Mark the deficient element on the bottle.

2. Place rooted plants through the corks in the bottles and cover all the bottles with black paper to protect the roots from light.

3. Allow the plants to grow for 10-15 days.

4. Change the nutrient solutions every 3-4 days.

5. Note the deficiency symptoms from each experimental set.

The various deficiency symptoms as expressed as foliar systems, growth of stems and roots are also noted against each treatments.

(B) Sand Culture Technique:

1. Washed sand or crushed quartz or vermiculite

2. Earthen pots (20 cm × 15 cm)

4. Inorganic nutrient solutions of desired types

1. Fill the earthen pots with washed sand or vermiculite.

2. Moisten the sand with water and one of the desired nutrient solutions (except control set, each set is efficient in one particular element).

3. Place one rooted plant in each pot and mark the deficient element.

4. Cover the upper surfaces of the pots to check evaporation of water vapour.

5. Allow the plants to grow for 2 weeks and then record the deficiency symptoms.

The deficiency symptoms against treatment condition is recorded.

Experiment # 2. Determination of Ionic Accumulation (Chloride) in Plant Cells:

Different mineral ions (anions or cations) are absorbed by actively growing plants — either by passive or active mechanism. Then the ions are accumulated in cell sap either in organic or inorganic combinations for a considerable period.

The ions can then be extracted from plant tissues and quantified by suitable titration methods.

Materials and Equipment’s Required:

3. Sand, water, activated charcoal

4. 0.02N AgNO3 soln. (0.34 gm. of AgNO3 per 100 ml soln.)

5. 5% K2CrO4 solution as indicator

6. Standard NaCl soln. (329.6 mg of dry NaCl per 1,000 ml solutions).

1. Weigh 10 gms of Hydrilla plants and crush them with neutral sand and distilled water in a mortar.

2. Dilute extract up to 50 ml by dist. water and then filter.

3. Remove chlorophyll by absorption with activated charcoal and subsequent filtering.

4. Titrate 10 ml of extract against 0.02N AgNO3 solution using a drop of 5% K2Cr2O4 soln. as indicator. The end point of titration is indicated by the appearance of a permanent faint reddish brown colour (due to formation of silver chromate AgCrO4).

5. Standardize the 0.02 N AgN03 against standard NaCl soln. using K2CrO4 indicator solution as mentioned above.

Let X ml of 0.02 N AgNO3 be standardized by Y ml of standard NaCl soln.

Now, 1 ml of standard NaCl contains 0.02 mg of chlorine

Therefore, Y ml of standard NaCl = 0.02 × Y mg of chlorine

Hence, X ml of 0.02 N AgNO3 = 0.02 × Y mg of chlorine

Now, 1 ml of 0.02 N AgNO3 = 0.03 × Y/X mg of chlorine

If the volume of 0.02 N AgNO3 to titrate 10 ml of plant extract be Z, then the amount of chlorine ion is


Macronutrients

Carbohydrates are the most important source of quick energy, but they also function in cell-membrane structure. They include the simple sugars glucose , fructose, and galactose the disaccharides maltose, lactose, and sucrose and the complex carbohydrates or polysaccharides , which are glycogen in human tissues and cellulose (fiber) and starch in plant tissues.

Lipids provide the body with more stored energy than carbohydrates do. They are also important as cell membrane components, steroid hormones , and visual pigments. Adipose tissue, which is mostly stored lipid, provides insulation and protection for the organs. About 95 percent of the body's lipid is in the form of triglycerides (fats).

Proteins are chains of amino acids . They are important structural components of cell membranes and the extracellular materials of bones, tendons, and other connective tissues , and all muscle contraction results from the action of proteins. Proteins also function as hormones , enzymes , and antibodies.

Water makes up most of the body. It is the body's major solvent, and it serves in lubrication, temperature control, and waste removal. A water deficiency can kill more quickly than a deficiency of any other nutrient.


Mineral Deficiency in Plants

The number of mineral ions uptaken by the plants should be in appropriate concentration. Any increase or decrease in the mineral ions concentration may cause mineral toxicity and mineral deficiency, respectively.

Mineral deficiency symptoms are characterized by the following factors:

  • Chlorosis, chlorophyll loss or leaf-yellowing occurs due to the lack of K, Mg, N, and S.
  • Necrosis or cell death results due to the deficiency of K, Ca, and Mg etc.
  • Inhibition of cell-division results due to the lack of N, K, B, and Mo.
  • Retarded growth is due to the deficiency of elements such as N, P, and Zn etc.
  • The deficiency of K and P causes leaf-foliage.
  • Deficiency of N, S, and Mo etc., results in delayed flowering.

Mineral toxicity symptoms are characterized by the following factors:

  • Brown spots appear due to Mn (Manganese) toxicity. Leaves are also surrounded by chlorotic veins. Mn-toxicity inhibits Ca translocation as well as competes with Fe and Mg for binding with enzymes. Thus, Mn toxicity causes Fe, Ca and Mg deficiency.

Important Terms

To describe the levels of nutrients in plants, we must go through the following terms:

  • Deficient: It is defined as the proportion of any nutrient mineral, which is low enough to cause deficiency symptoms in plants.
  • Critical range: It is the proportion of mineral nutrients below which plant yield is reduced.
  • Sufficient: It is the concentration range of essential nutrients, which only increases nutrient consumption. Luxury consumption is another term used to denote sufficient mineral consumption. It does not increase the plant yield.
  • Excessive or toxic: It is the concentration range of essential nutrients, which is large enough to cause mineral toxicity on the plants. It causes ion imbalance, thereby retards plant growth.

Mechanism of Mineral Nutrition in Plants

The plants absorb minerals or nutrient ions through their roots from the soil. A stele is a structure within the root system, which allows the passage of mineral ions to the conducting tissues. Water potential decides the path of nutrient absorption. The mechanism of mineral nutrition in plants can be summarized into two phases.

During the first phase, the mineral salts or ions in soil move into the plant cells’ free space or apoplast. Here, the ions’ movement does not need energy expenditure, as they move from the region of high to low concentration.

Thus, the first phase of mineral nutrition involves the passive transport of the ions. It is important to keep in mind that the movement in the first phase is rapid and mediated via ion-channels and transmembrane proteins.

In the second phase, the mineral salts or ions move into the plant cells’ inner space or symplast. Here, the ions’ movement needs expenditure of energy as they move from the region of low to a high concentration. Thus, the second phase of mineral nutrition involves the active transport of ions.

We should remember that the movement of ions in the second phase are quite slow and mediated via plasmodesmata. The ions from the apoplast and symplast enter the xylem cells, which cause conduction of water upwards or to the plants shoot system.


Mineral Nutrition in a Plant | Term Paper | Biology

Here is a term paper on the ‘Mineral Nutrition in a Plant’ for class 9, 10, 11 and 12. Find paragraphs, long and short term papers on the ‘Mineral Nutrition in a Plant’ especially written for school and college students.

Term Paper # 1. The Importance of Nitrogen-Containing Ions:

Living organisms need proteins for growth and repair. Plants have to manufacture (‘synthesise’) their own proteins. To do this, they convert their carbohydrates into amino acids, and then link the amino acids together to form proteins.

Nitrogen is another element plants need to be able to convert carbohydrate into amino acid. Plants absorb nitrogen, as the nitrate ion (NO3 _ ), from the soil through root hairs. Nitrogen makes up about 79% of the atmosphere, but plants cannot make direct use of it in this form.

To Show the Effects of a Lack of Nitrogen on the Growth of a Plant:

i. Two small cuttings or seedlings

iv. Black paper or black polythene

v. Culture solutions (available from suppliers)

Two seedlings (e.g. sorghum), or small cuttings with the same number of leaves are selected from a quick-growing plant and held in the top of two containers (A and B) using cotton wool, as shown in Fig. 27.

Container A contains a ‘complete culture solution’, i.e. a solution comprising all the necessary salts dissolved in distilled water (supplying the following ions- potassium, calcium, magnesium, iron, nitrate, sulphate and phosphate). A complete culture solution can be made by dissolving 1 g calcium nitrate, 0.25 g each of potassium nitrate, magnesium sulphate and potassium phosphate, and a trace of ferric chloride in 1 litre of distilled water.

Container B contains a similar solution, but lacking in nitrate ions. (Use calcium and potassium chlorides instead of nitrates when making up the solution.)

The two containers are left in light and at a suitable temperature. It is advisable to blow air into the solutions each day, using a small glass tube.

Container A (the Control)- Seedling grows tall and healthy, with vigorous root growth.

Container B: Seedling fails to grow, leaves begin to die and root system fails to develop.

Nitrogen (present in nitrates) is needed for the healthy growth of plants.

Term Paper # 2. The Importance of Magnesium Ions:

Magnesium ions, like nitrates and other ions are absorbed from the soil through the root hairs. Magnesium is the central atom in a chlorophyll molecule. Plants grown in soils deficient in magnesium ions develop yellow leaves (a condition called chlorosis).

Insufficient chlorophyll can be made so photosynthesis is restricted. Insufficient carbohydrates are manufactured, the respiration rate is slow and few proteins can be made. Growth is therefore limited.

Term Paper # 3. The Use of Nitrogen-Containing Ions in Agriculture:

Normally, plants obtain their nitrates from decaying organic materials in the soil. However, agricultural land often lacks this organic matter. To increase the amount of nitrates available to crops, a farmer may add artificial nitrogen- containing fertilisers (e.g. nitrate or ammonium salts, which soil bacteria will convert into nitrates – see the section on the nitrogen cycle, below). The fertiliser boosts the growth of the crop, and the farmer can get a quick and high yield.

The Dangers of the Overuse of Artificial Fertilisers:

Although better crops are produced by using artificial fertilisers, there is a danger that the readily soluble nitrates will be washed into streams, rivers and lakes.

(i) An abundant growth of water plants (eutrophication).

(ii) When these plants eventually die, they are decayed by bacteria which use up the oxygen in the water resulting in the death of the water animals such as fish.

(iii) If this water is used as drinking water by humans, the high levels of nitrate may lead to cancer of the stomach.


Nutrition in Plants : Macroelements, Their Role and Deficiency Symptoms in Plants

Nutrition is the process by which living organisms take their food for maintaining proper growth, metabolisms and replacement of tissue. Plants nutrition occurs in two phases such as synthesis and assimilation. Generally, plants nutrition is of two types such as autotrophic plant nutrition and heterotrophic nutrition.

Autotrophic Plant Nutrition

In autotrophic nutrition, the plant gains simple and inorganic food elements in the form of liquid and gases. In this case, plants obtain energy needed for synthesis of food from the sun. The process by which glucose is synthesized from CO2 and H2O in the presence of sunlight by the help of chlorophyll is known as photosynthesis.

Glycerol, fatty acids, amino acids, and other carbohydrates are synthesized from glucose and are stored up complex forms in the leaves, stems, and roots for future use. These stored materials can be transformed into simple soluble foods by specific enzymes and later on the digested food materials are assimilated to form protoplasmic constituents.

The nutritional requirements of autotrophs include several inorganic ions. These are obtained from the surroundings and are called essential elements.

Heterotrophic Plant Nutrition

Plants which are devoid of chlorophyll are incapable of producing their own food within their body, known as heterotrophic plant nutrition. In this case, plants depend on green plants for their nutrition. In these plants, the mode of digestion is extracellular. Heterotrophic plant nutrition is of following types:

Parasitic Nutrition: The process by which a plant obtains its necessary nutrition from any other plants or animals is known as parasitic nutrition.

Saprophytic Nutrition: The nutrition of certain non-green plants which extract their nourishment from the dead and decomposed organic substance formed as a result of the decay of plants and animals is called saprophytic nutrition. e.g. Agaricus.

Symbiotic Nutrition: When two organisms live in close association with each other for their mutual benefit in nutrition, then the type of nutrition is called symbiotic nutrition. Each of the pair is called symbiont and the mode of their association is known as symbiosis. e.g. Rhizobium living in the root nodules of leguminous plants are capable of fixing atmospheric nitrogen to help in ammonia production, which is taken by the leguminous plants and in lieu of which they supply carbohydrate food to the symbiotic bacteria, Rhizobium. Symbiotic nutrition also lies between plants and animals such as Zoochlorella and Hydra. Symbiotic nutrition is of two types:

(1) Mutualism: When two plants live in close association for mutual benefit in obtaining their nutrition, the type of nutrition is known as mutualism. e.g. Lichen. This formed between algae and fungus whereas the fungus extracts in carbohydrate type of food matters and oxygen from the algae. In this case, the fungus protects the algae from drying up.

(2) Commensalism: When two plants living together to obtain their nutrition independently then the type of nutrition is known as commensalism. This type of plants does not affect their hosts as they are capable of preparing their own food. e.g. Ficus (Banyan tree).

Plant Nutrients

Plants nutrients are the chemical substances which are essential for the proper growth of the plant. It is divided into two types on the basis of requirements by the plants such as macro- and micronutrients. There are many factors which influence the uptake of nutrients for plants. Plants receive mineral nutrients by absorbing with the help of roots as ions in soil water. Each of the nutrients plays an important role in plant health and growth.

Essential elements which are required in large amounts are called macroelements. Whereas the elements which are required in minute quantities or traces are called trace elements. These elements help the plants for proper growth and nutrition. In the absence of any of nutrient elements, normal growth of the plant is disturbed and different deficiency symptoms are exhibited by the plants. Plants require about 90 nutrient elements. Among them, 16 elements are distinguished as essential for plants.