Agriculture notes prepared by IAS Topper for all agriculture based competitive exams-Physiology-Transpiration

Transpiration

Difference between Transpiration and Evaporation……………

Difference between Transpiration and Gutation………………..

Transpiration is Unavoidable: Transpiration is incidental because of presence of stomata, which are important for gaseous exchange. So for photosynthesis and respiration to happen in plants, transpiration has been an added phenomenon.

Transpiration is Dangerous: Loss of water does not serve any good purpose in plant life. Many plants die due to over transpiration. Unnecessary energy consumption by the plant due to transpiration and water absorption by roots is also a undesirable effect.

Transpiration is Necessary: Chief function of transpiration is dissipation of canopy heat, which is absorbed by plant from sun. Therefore, transpiration avoids sunburn injury to plants.

Transpiration is advantageous to plan:

• For Ascent of sap in taller plants
• Absorption of water and minerals by root
• Evaporation of excess water
• Translocation of food materials in plants
• Maintenance of suitable temperature of leaves
• Bring out opening and closing of stomata and therefore indirectly controlling photosynthesis and respiration.

How stomata open and close?

The most accepted theory is proton transport and hormonal regulation

Opening of stomata:

Influx of proton ions inside the guard cells increases the osmotic concentration of guard cells. The osmotic entry of water from outside results in turgidity thereby the stomata open. The entry of potassium ions is balanced by outflow of hydrogen as well as equal negative charges inside. It is provided by the organic acids resulted out of physiological mechanism in guard cells. Therefore possible pathway is

Light-Malic acid production from starch---Dissociation into malate ion and H---influx of potassium ions and outflow of H---transport of potassium malate into vacuoles---osmotic entrance of water into guard cells---increase in turgor pressure-opening of stomata

Closing of stomata

Abscisic acid is responsible for the closing of stomata. This growth retardant inhibits potassium uptake by changing the diffusion and permeability of guard cell. Potassium moves out of the guard cells followed by lowering down of PH of the cell by ABA mediated acidification. Therefore osmotic concentration in guard cell reduces, and water moves out of the subsidiary cells. Therefore stomata become flaccid and remain closed.

Factors affecting rate of transpiration

a) External factors

• Water vapour saturation deficit
• Temperature
• Wind velocity (mild wind increases transpiration)
• Light increases the leaf temperature and also controls the opening and closing of stomata
• Atmospheric pressure increases transpiration as it decreases
• Water supply to the plant

b). Internal factors

• Stomatal frequency – No. of stomata per unit area of leaf surface. Stomatal Index is used as a reference for calculating stomatal frequency

  S

I =

            E+S

 I - Stomatal Index

S - No. of stomata/unit area,

E - No. of epidermal cells/unit area

• Structural peculiarities as the No. of stomata and their distribution differs from plants of xerophytes to hydrophytes. Ex. Sunken stomata

 Gutation…………………..

Fatty Acid Metabolism

Lipid=Fatty acid=Glycerol

So three important events are important for synthesis of lipids

a). Synthesis of Fatty acid

Basic Material: Acetyl COA

Other Factors: Biotin, Mn++, ATP and CO2

Addition of two carbons at a time to a carbon skeleton, because Acetyl COA is added at every step during Fatty acid synthesis. That is why fatty acids have carbon atoms even in number.

Steps

 

Agriculture notes prepared by IAS Topper for all agriculture based competitive exams-Physiology-Respiration

Respiration

Formation of Glycerol

Basic material: Dyhydroxy Aceton Phosphate

DHAP---Glycerophosphate---Glycerol

Condensation

During this process, COA plays an important role.

Fatty acid + COA---- FA-COA complex

FA-COA complex + Glycerol------------Lipid + COA

 Lipase

Catabolism

Saponification: The reverse process of condensatin, where in the lipid is degraded into fatty acid and glycerol. Then fatty acid and glycerol undergoes oxidation separately

Fatty acid Oxidation: it happens in three different ways

1. Beta-oxidation
2. Alpha-oxidation
3. Peroxidation

Beta-oxidation is the most important process of all these above process. Let us see it to some extent

Mechanism: COA plays important role in the oxidation of fatty acids. Its addition with a lipid molecule and repeated hydration and dehydration results in separation of one acetyl COA at each cycle.

            COA

Lipid---- ----- ----- ----- ----- ----- Acetyl COA

            H2O/-H2O

Glyoxylic acid cycle

Once acetyl COA if formed, the energy is obtained by following steps.

Acetyl COA-------- Succinic acid

Succinic acid-------- Oxaloacetic acid

Ocalo acetic acid-------- Sugar/Sucrose

Sugar/sucrose----------- Energy

These steps clearly show that the process is just a reverse of the Glycolysis and Kreb cycle.

Agriculture notes prepared by IAS Topper for all agriculture based competitive exams-Physiology-Nitrogen Cycle

Nitrogen Availability in soil and atmosphere (N2 cycle)

(Nitrogen Cycle)

Sources:

• Volcanic soil contains minerals of nitrogen which degrade and become available in the soil after weathering and soil forming process are over
• Electrification and photochemical fixation of atmospheric nitrogen
• Atmospheric nitrogen fixation by the symbiotic and non-symbiotic organisms
• Decay of dead organic matter and excretion

 Process involved in nitrogen cycle

• Nitrogen fixation by biological organisms and lightning-freely available nitrogen in the atmosphere is converted into ammonia by physical and bio-chemical process

N-N-------N+N----------2NH3

• Ammonificaiton-conversion of organic matter into ammonia/ammonium

Dead organic matter------------ Ammonia

• Nitrification-conversion of ammonia/ammonium into nitrite/nitrate

Ammonia---------------Nitrite (by nitrosomonas)

Nitrite-------------------Nitrate (by nitrobacter)

• Denitrification-conversion of nitrite/nitrate into gaseous nitrogen

Nitrite/Nitrate-------------Ammonia-----------Nitrogen

Biological Nitrogen fixation

Symbiotic fixaton:

It is grouped into two groups

Fast growers:  Rhisobium legunimosarum

                        Rhisobium meloloti

                        Rhisobium trifoli

Slow growers: Rhisobium japoinicum

                        Rhisobium lupinii

Nodule formation

a). Host recognition: It is controlled by a specific protein in the host called lectin, which interact selectively with microbial cell carbohydrate (glycoprotein) present in capsule of bacteria. Calcium ions also plays a crucial role in modifying the ability of root to absorb Rhizobia.

b). Nodulation: 

• Rhizobium does not have cellulose, therefore it enters through tip of root haris which is not having any cellulose. Plant releases the tryptophan into soil, which is absorbed by bacteria and metabolize it to produce Indole Acetic Acid.
• Rhizobium produces root hair culing factor which deform and twist root hair after penetration. Root hairs are subsequently penetrated by large number of Rhizobia, root hair curls and converted into an infection thread lined by cellulose which is provided by the host cell. This thread releases its content (bacteria) into cortical cells. Liberated Rhizobia may be in polyploid single or in small groups enclosed by a membrane.
• Bacteria assumes a pleomorphic shape and are called as baceroids. They induce polyploid cells and diploid cells of cortex and others to undergo multiplication (IAA). Thus nodules are formed.
• Legheamoglobin is a pink pigment produced only in host Rhizobial interaction which is important for providing anaerobic condition.

Nitrogenase enzyme

• Function: Provides surface for attachment of nitrogen and fixes atmospheric nitrogen into ammonia
• Substrates: Atm. N2, N2O and acetylene
• It consists of two protein components
• Mo-Fe protein component contains one Mo for every 2-3 lakh units
• Fe protein component, has molecular weight of 55,000 to 65,000 Dalton 

• Enzyme is very sensitive to oxygen and higher oxygen content in the atmosphere denatures the enzyme. Therefore, plants have evolved Leghaemoglobin and heterocysts. Enzyme also undergoes confirmational changes so that it becomes insensitive to oxygen content or the excess oxygen is utilized for oxidation of other substrates.
• Functions of Leghaemoglobin:
• Removal of oxygen to provide anaerobic condition
• Provide oxygen to bacteroid for ATP production which in turn generate electron for fixation

Mechanism: Atmospheric nitrogen attaches/binds on enzyme surface and is not released until it is completely reduced to ammonia.

N-N ---------- bond broken N+N ------------------- NH3

Reaction: There are three important conditions required for this process

• Availability of ATP through respiration of bacteroids
• Availability of reduced substrate, Glucose-6-phosphate from host and reduced NADP together ferredoxin (electron carrier)
• Enzyme nitrogenase for fixing of N2 on its surface

Steps:

• Glucose-6-phosphate provide hydrogen for the reaction. ATP interacts with non-haeme iron protein (NHI) component of nitrogen and brings about confirmational changes to convert it to powerful reductants so that they are capable of transferring electron to reduce nitrogen NH3

Note: Six electrons are needed to reduce one molecule of nitrogen to produce 2NH3. Therefore tow electron release, 4ATPs required. At least 12 ATPs are required to reduce one molecule of nitrogen into two NH3

Nitorogen cycle Flow diagram………………………………………………

Agriculture notes prepared by IAS Topper for all agriculture based competitive exams-Physiology-Types of Stomata

Types of Stomata

 Based on distribution of stomata

• Apple/Mulberry type = hypostomatic
• Wild lilly type = epistomatic
• Oat type = amphistomatic and Isostomatic
• Potato type = amphistomatic and anisostomatic
• Potamogeton type = astomatic

 Based on stomatal clock

• Equisetum type
• Alfalfa type
• Potato type
• Barely type

 Based on movement

• Photoactive stomata
• Skotoactive stomata
• Hydroactive stomata
• Automatic stomata
• Active and passive stomata

 Based on subsidiary cells arrangement

• Anomocytic type : Ex. Ranunculaceae
• Anisocytic type : Ex. Cruciferae, Solanaceae
• Paracytic type : Ex. Rubiaceae, Magnoliaceae
• Diacytic type : Ex. Caryophyllaceae
• Actinocytic type
• Cyclocytic type

 Based on ontogeny

• Haplocheilic type - guard cells and subsidiary cells originate separately
• Syndetocheilic type – guard cells and subsidiary cells originate from same mother cell

Agriculture notes prepared by IAS Topper for all agriculture based competitive exams-Physiology-Growth Regulators

Growth regulators

Bioassay for different growth regulators

 Auxin:

• Split pea test
• Avena coleoptile test
• Rice root inhibition test

 Gibberellin

• Barely endosperm test (production of reducing sugars)
• Elongation of dwarf seedlings

 Cytokinin

• Chlorophyll retention test
• Root inhibition test

 Abscisic Acid (ABA)

• Inhibition of alpha amylase enzyme
• Rice seedling growth inhibition test

 Ethylene

• Triple pea test (special thickening, horizontal nutation, rate of reduction of elongation)
• Pea stem swelling test

 Senescence

“The process of deterioration that accompany aging and that lead to death of an organ or organism are called as senescence”. Meristematic regions do not senesce but non-meristematic regions senesce

Ex. Decidous plants drop old leaves every year

Reason:

Senescence occurs due to loss of chlorophyll, RNA and proteins including many enzymes. This is brought out by two ways,

• Slower synthesis of vital plant components due to diversion or deficiency of nutrients
• Breakdown of vital components by hormone induced process or by any means

 Role of hormone in Senescence

• ABA and Ethylene induce senescence
• Cytokinin, givverellic acid and auxin prevent senescence.

Therefore the change in the status of these hormones affects the onset of senescence.

 Advantages of senescence

• Fruit: dispersal of seeds
• Flower: prevents diversion of excess nutrients to flower, avoid shadding and new infection sources.
• Leaves: reduce transpiring surface and more nutrients are diverted to fruits and other vital parts of the plant

• me mother cell

Agriculture notes prepared by IAS Topper for all agriculture based competitive exams-Physiology-Fruit Ripening

 Fruit Ripening

 Changes during fruit ripening

 Bio-chemical Changes:

a). Softening: Cell wall degrading enzymes become active and degrade the cell wall of the fruit tissues. Pectinases, polygalacturanase, cellulase, hemicellulase etc. are some of the enzymes found more active during this phase of fruit ripening.

b). Hyderolytic conversion of reserve food materials into edible sugars like fructose, glucose etc.

c). Change in pigments and flavour: In presence of light and phytochrome, chlorophyll is degraded by chlorophyllase, thereby changing the colour of the fruits. Many of the phenolic and other astringent materials disappear and fruits become edible

Respiratory climatric:

During ripening of fruits, respiration rate increases and based on it, fruits are grouped into climatric and non-climatric fruits.

The most important hormone involved in regulation of fruit ripening is Ethylene. The amount of this hormone increases as the fruit advances to ripening.

Agriculture notes prepared by IAS Topper for all agriculture based competitive exams-Physiology-Dormancy

Stress physiology

 Dormancy

Dormancy is a special adaptation to overcome unfavorable condition. Dormancy is a temporary suspension of physiological activity or growth, though conditions are favourable for normal growth and developments. There are three types of dormancy

1. Imposed dormancy due to the physical condition like deep sowing of seeds.
2. Innate Dormancy is by the nature of the material undergoing dormancy
3. Secondary or induced dormancy means artificial induction of dormancy

 Bud dormancy

 Induction of bud dormancy

Bud is unexpanded leaf primordial covered by stipules or leaves. Mostly in woody plants, located in temperate regions in late summer or autumn, the whole plant enters resting. In tropical plants both dormant and active buds.

 Reason for bud dormancy

• Due to change in day length
• Role of phytochrome in regulating the dormancy
• Exhaustion of nutrients
• Presence of chemical inhibitors like ABA

 Removal of bud dormancy

• Treatment of plant buds with winter chilling at 1-10oC for a period of 260 to 1000 hours
• Transferring seeds from short day to long day condition
• Use of chemicals like ethylene chlorhydrin, thiourea and dinitrophenol to break the dormancy
• Providing warm bath to dormant buds at 40oC
• Application of gibberellins found to break the dormant buds

 Seed Dormancy

Dormancy of seeds depend upon three main factors

• Stage and nature of development of seed embryo
• Seed coat permeability to
• Imbibition of water to activate enzymes and others so that stored food is utilized and germination process initiated.
• Permeable to oxygen to initiate respiration, so that more energy is supplied to embryo

Mechanism of Seed dormancy

 Two schools of thoughts

1. Interference with gaseous exchange by seed coat and other structures even it may be a barrier for imbibition of water.
2. Seed dormancy due to immature embryo: Seeds are shed with immatured embryo which needs after ripening period to complete development
3. Hormonal control: Deficiency of some essential growth promoting substances such as gibberellins result in seed dormancy. However, gibberellins found to replace the chilling requirements thereby breaking the dormancy. Active inhibitors like dormin or abscissin promote seed dormancy.
4. Light: Red light found effective against seed dormancy but infrared light induce dormancy

Overcoming seed dormancy

a). Hard seed coat:

• Seed scarification- mechanical scarification with abrasive materials
•  Soaking of seeds in water to soften the seed coat
• Washing seeds with sulphuric acid and then soaking in water to remove the acid
• Microbial decomposition of seed coats

b). Immature embryo

• Storing of seeds for some period of time until embryo completely develops

c). Chemical inhibitors

• Chilling or heat treatment of seeds to inactivate/destroy the chemical inhibitors responsible for seed dormancy
• Seed stratification (placing seeds in different layers of soils) to wash out the chemical inhibitors and also to stimulate synthesis of growth promoters

d). Light sensitivity: use of red and infrared lights according to the requirements

e). Chilling treatment done for temperate plants

Cold tolerance

Low temperature causes damages to plants in three ways

1. Presences of water in inter cellular space freezes at low temperature. As the temperature goes down drastically, the water freezes into crystals. These inter cellular crystals pulls the protoplasmic water of cells, leading to dehydrations.
2. Dehydration of cells results in increased of salt concentration of the plant. Both the dehydration and increase in salt concentration denature vital preoteins and active enzymes.
3. Ice crystals enlarge in intercellular spaces and break the cellular membranes

 Overcoming cold stress

• High cell wall permeability
• Increased free proteins and enzymes provide resistant to dehydration and low temperature

 Salt tolerance

 Problems

• Most important problem at high soil concentration is the water regulation. Since the water concentration is high on outer environment, plant has to pull water against negative water potential. So plants will suffer from physiological dryness.
• Accumulation of high concentration of Na+, SO4- and Cl- will be toxic to plants
• Absorption of K+ becomes critical as Na+ competes better than it.

 Overcoming salt tolerance

• Accumulation of more solutes in cells further reduces the water potential, so that water can be absorb ed from soil with ease.
• Synthesis of large quantity of amino acid, Proline, other important amino acids and organic compounds involved in osmoregulations.
• Salt regulators/succulents tide over the high salt concentration by maintaining low salt concentration
• Exudation of excess salts to avoid accumulation of salts to toxic concentration

Quotable Quote-Message of the Day

A friendless Life is like a flowerless garden. But I have a beautiful garden with wonderful flowers. One of my flowers is reading this message…

Quotable Quote-Message of the Day

As a believer in God you can confidently say, “Although I don’t know what the future holds, I know who holds the future!”

Free essays for Competitive Exams-NCC: Grooming tomorrow’s Leaders

NCC: Grooming tomorrow’s Leaders

The foundation of the National Cadet Corps (NCC) on 16 July 1948 under an Act of Parliament was perhaps the finest event for the student community of India. The aftermath of the Kashmir war in 1948 taught a very important lesson that freedom needs to be protected by a strong Armed Force. It’s immediate manifestation was appointment of Kunzru Committee based on whose recommendations a draft bill was placed before the Constituent Assembly on 13 March 1948 which evoked great interest and enthusiasms amongst all members. After due deliberations and amendments the Bill was passed by the Assembly on April 8, 1948. The Central Government accepted the opinion of the provincial Government for the formation of a Cadet Corps which was to be later named as ‘National Cadet Corps’ as recommended by the Kunzru Committee. The bill received the assent of the Governor General on 16 April 1948 and thus, National Cadet Corps came into being.

Evolution & Growth

  The NCC has evolved over the years. Initially NCC Rifles was raised on the lines of an Infantry Battalion but was later amalgamated into normal units. In the after math of Chinese aggression, NCC was made compulsory in 1963 for all students where in the Cadets strength reached 17.16 million. This large strength was later found to be unsustainable and hence voluntary enrolment was recommended in 1969 and is followed till date.

  The NCC is a Tri-Service Organisation, headed by a Director General of the rank of Lieutenant General of the Army. There are 17 Regional Directorates controlling the training and administration of NCC units under them with each headed by an Additional Director General or Deputy Director General of the rank of Major General or Brigadier or equivalent ranks of the Navy and Air Force. At present there are 96 NCC Group HQs and 800 units located throughout the country providing NCC coverage to 633 districts.

  Today NCC India is the largest volunteer uniformed youth organisation in the world and 13.4 lakh strong. The Government has ordered increase in enrolment to 15 lakhs by the year 2015. Many nations have emulated the Indian model successfully and have regular cadet exchange under the Youth Exchange Programme (YEP). Indeed the sight of proud and smartly turned out NCC cadets marching past the President on Republic Day  on the Rajpath brings joy and pride to every Indian and reassures them the bright future and greatness of our nation.

NCC Motto-Unity and Discipline

A person’s character is made in the formative years of his life. The young can be compared to wet clay which can be moulded the desired way, provided right training and directions are given. In ancient India young boys stayed with great saints, sages & pundits and specialized in various branches of knowledge. They learnt a lot from each other. They also learnt the art of corporate living and to fend for themselves in inhospitable surroundings. On similar analogy to impart right direction to the youth of our country, enrolment in the NCC takes place at a time when entrants are in their most formative years. At this stage National Cadet Corps plays the role of a friend, philosopher and guide channelizing their immense talent in the right direction and grooming them to become tomorrow’s leaders. The NCC training not only directs their energy into constructive channels but also inculcates in them the traits and qualities of resourcefulness, positive thinking, moral courage and humaneness – so that they can live up to the motto of the NCC, “Unity and Discipline”.

The current aims of the NCC emphasize on harnessing the youth into potential leaders, patriotic citizens who are well motivated to opt for a career in the Armed Forces. Keeping the current aims in view, the training activities of the NCC have been clearly formulated into four broad categories, namely, Institutional Training, Social Service, Community Development Programmes and Youth Exchange Programme.

Facets of Training

Institutional Training is conducted at the college and school levels. This is the mainstay of NCC training and is conducted by Associate NCC officers and Armed Forces personnel drawn from the three services that is Army, Navy and Air Force (under deputation in the NCC).

Camp Training: The aim of this training is to expose the cadets to a regimented way of life.  In addition to Annual Training camps, cadets are also sent on national level camps like the Special National Integration camps, National Integration camps and Leaderships Camps etc. where they meet and interact with cadets from all states and Union Territories and have their team and leadership skills.

Social Service & Community Development: Participating in campaigns, like Adult Literacy Promotion, Anti-Polio Drive, Rural Development Trial Project, AIDS Awareness, Tree plantation and Anti-Drug programme etc. aim to inculcate in cadets the moral and social obligations to fellow citizens and to ‘Nation Building’.

Youth Exchange Programme: Selected cadets are given an opportunity to visit foreign countries as their State Guests and as the ‘Brand Ambassadors’ of our nation.

Adventure Based Learning: The cadets are also exposed to a number of adventure activities that enable them to improve their life and leadership skills. Mountain Treks & Expeditions, Parasailing & Jumping, Sailing Expeditions and Micro lite flying are some of the events conducted regularly by the NCC.

Sports: NCC teams regularly excel in National level events like Subroto Cup Football, Nehru Cup Hockey, and National Shooting Championships.

Personality Development: The revised training philosophy of the NCC specifically aims to add value to the cadets’ life skills and enable them to excel in all walks of life.

How NCC Helps

In Defence Services- Vacancies reserved for commission in the three services for NCC ‘C’ certificate holders are as follows:

·         Army: At Indian Military Academy (IMA) Dehradun 32 vacancies per course through UPSC and SSB Interview.

OTA Chennai & Gaya- 50 vacancies every year for short service commission in Non - Technical categories. The candidates come through SSB interview only.

·         Navy: Six vacancies per course. Selection is through SSB interview. Two years age relaxation for NCC ‘C’ Certificate holders.

·         Air Force: 10% of vacancies in all courses including flying training course. Selection through SSB interview.

For Other Ranks (OR), Sailors & Airmen- 5 to 10% bonus marksare awarded for recruitment.

Others

Para-Military Forces Recruitments- 2 to 10% bonus marks are awarded for recruitment.

Deptt. of Telecommunications: Special Bonus marks are awarded for recruitment.

In NCC: Preference is given to ‘C’ certificate Holders for appointment as Civilian Gliding Instructors/Girl Cadet Instructors / whole time lady officers in NCC.

In State Government: Preference for State Services particularly in Police, Admn, Forest, Excise and Transport department.

Scholarships:  NCC cadets are eligible for scholarships ranging from Rs 6000/ to Rs 30,000/ through cadet welfare society and Sahara Scholarships.

Sports: Attractive cash awards to teams and individuals for showing excellence in national and international competitions / championships.

  The NCC, the largest organised youth force in the world has, over a period of time earned a niche for itself as a unique organisation in ‘ Nation Building’ and grooming the youth of our country. The organization through its multifarious innovative training curriculum and conduct of a large number of national integration camps has made invaluable contributions towards achieving national integration. History shows that, over the years the NCC has groomed many a youth into leaders of repute and eminence whose, deeds are worth emulating. The pioneers being Netaji Subhas Chandra Bose, Air Marshal Subroto Mukherjee, former Chief of Air Staff, Gen T. N. Raina and General Deepak Kapoorboth former Chiefs of Army Staff, Marshal of the Air Force Arjan Singh, Admiral Nirmal Verma, former Chief of Naval Staff, Dr. M.S Gill, former Chief Election Commissioner, Ms Jaya Bhaduri MP, noted film actress and best cadet of R. D Camp- 1966 and many more. Realising the crucial role of NCC, Ministry of Human Resources Development, in a pilot project has recently taken decision of introducing NCC as an elective subject in selected undergraduate institutions. This step will definitely give a boost to NCC‘s efforts.