The document discusses two main types of pollination: autogamy (self-pollination) and allogamy (cross-pollination). Autogamy occurs when a pollen grain is transferred from the anther to the stigma of the same flower and is promoted by traits like bisexuality, homogamy, cleistogamy, and chasmogamy. Allogamy involves transfer of pollen between different plants and is encouraged by dicliny, dichogamy, heterostyly, herkogamy, and self-incompatibility. The mode of pollination influences plant breeding by affecting gene action, genetic constitution, adaptability, genetic purity, and gene transfer.
Pollen pistil interaction
Types of Incompatibility in plants
Methods to overcome Incompatibility
Prepared by
Dr. T. Annie Sheron
Assistant Professor of Botany
DEPARTMENT OF BOTANY
KAKATIYA GOVERNMENT COLLEGE, HANAMKONDA
The modes of reproduction in crop plants may be broadly grouped into two categories: asexual and sexual.
Sexual reproduction involves the fusion of male and female gametes, whereas in asexual reproduction new plants may develop from vegetative parts of the plant (vegetative reproduction) or may arise from embryos that develop without fertilization (apomixis).
Pollination, transfer of pollen grains from the stamens, the flower parts that produce them, to the ovule-bearing organs or to the ovules (seed precursors) themselves. In plants such as conifers and cycads, in which the ovules are exposed, the pollen is simply caught in a drop of fluid secreted by the ovule. In flowering plants, however, the ovules are contained within a hollow organ called the pistil, and the pollen is deposited on the pistil’s receptive surface, the stigma. There the pollen germinates and gives rise to a pollen tube, which grows down through the pistil toward one of the ovules in its base. In an act of double fertilization, one of the two sperm cells within the pollen tube fuses with the egg cell of the ovule, making possible the development of an embryo, and the other cell combines with the two subsidiary sexual nuclei of the ovule, which initiates formation of a reserve food tissue, the endosperm. The growing ovule then transforms itself into a seed.
Apomixis in flowering plants is defined as the asexual formation of a seed from the maternal tissues of the ovule, avoiding the processes of meiosis and fertilization, leading to embryo development.
Pollen pistil interaction
Types of Incompatibility in plants
Methods to overcome Incompatibility
Prepared by
Dr. T. Annie Sheron
Assistant Professor of Botany
DEPARTMENT OF BOTANY
KAKATIYA GOVERNMENT COLLEGE, HANAMKONDA
The modes of reproduction in crop plants may be broadly grouped into two categories: asexual and sexual.
Sexual reproduction involves the fusion of male and female gametes, whereas in asexual reproduction new plants may develop from vegetative parts of the plant (vegetative reproduction) or may arise from embryos that develop without fertilization (apomixis).
Pollination, transfer of pollen grains from the stamens, the flower parts that produce them, to the ovule-bearing organs or to the ovules (seed precursors) themselves. In plants such as conifers and cycads, in which the ovules are exposed, the pollen is simply caught in a drop of fluid secreted by the ovule. In flowering plants, however, the ovules are contained within a hollow organ called the pistil, and the pollen is deposited on the pistil’s receptive surface, the stigma. There the pollen germinates and gives rise to a pollen tube, which grows down through the pistil toward one of the ovules in its base. In an act of double fertilization, one of the two sperm cells within the pollen tube fuses with the egg cell of the ovule, making possible the development of an embryo, and the other cell combines with the two subsidiary sexual nuclei of the ovule, which initiates formation of a reserve food tissue, the endosperm. The growing ovule then transforms itself into a seed.
Apomixis in flowering plants is defined as the asexual formation of a seed from the maternal tissues of the ovule, avoiding the processes of meiosis and fertilization, leading to embryo development.
Plant breeding methods of vegetatively propagated crops Roksana Aftab Ruhi
Vegetatively propagated crops are bred by intentionally crossing of closely or distantly related individual to produce new crop varieties or lines with desirable traits. Breeding of vegetative crops have successfully improved quality, yield, tolerance of crops to environmental pressure. Breeding helps in producing crops that are resistant to viruses, fungi and bacteria and helps in longer storage period for the harvested crop.
Pollination : Types and significance.
The Seminar presented by Biswajit Das
L.T.K. College, Department of Botany.
In order that a plant is able to produce seeds, the male and female gametes must come together.
The male gamete is produced by the androecium within the pollen grain, while the female gamete is produced by the gynoecium within the ovule.
Pollination is the process that helps in bringing male and female gametes together.
Self-pollination and cross-pollination are two major ways. Flowering plants are adapted to use vivid agents, like biotic and abiotic.
.............................................................. Thank You.
Pollination Detailed Explanation with examples Sumita Sinha
Pollination and Its types with examples.Contrivances of self - Pollination and Cross - Pollination.Agents of Pollination is also clearly mentioned.The topic is clearly explained with relevant images for better understanding.
Modes of Pollination.pptxhsbsbshshs hdhjZackAbukar
Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspect
Plant breeding methods of vegetatively propagated crops Roksana Aftab Ruhi
Vegetatively propagated crops are bred by intentionally crossing of closely or distantly related individual to produce new crop varieties or lines with desirable traits. Breeding of vegetative crops have successfully improved quality, yield, tolerance of crops to environmental pressure. Breeding helps in producing crops that are resistant to viruses, fungi and bacteria and helps in longer storage period for the harvested crop.
Pollination : Types and significance.
The Seminar presented by Biswajit Das
L.T.K. College, Department of Botany.
In order that a plant is able to produce seeds, the male and female gametes must come together.
The male gamete is produced by the androecium within the pollen grain, while the female gamete is produced by the gynoecium within the ovule.
Pollination is the process that helps in bringing male and female gametes together.
Self-pollination and cross-pollination are two major ways. Flowering plants are adapted to use vivid agents, like biotic and abiotic.
.............................................................. Thank You.
Pollination Detailed Explanation with examples Sumita Sinha
Pollination and Its types with examples.Contrivances of self - Pollination and Cross - Pollination.Agents of Pollination is also clearly mentioned.The topic is clearly explained with relevant images for better understanding.
Modes of Pollination.pptxhsbsbshshs hdhjZackAbukar
Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspects of that system, such as its structure, leadership, program, methods and techniques, resources, and linkages.Definition: Extension approaches can be defined as a style of action, embodying the philosophy of an extension system which, by and large determines the direction and nature/style of the various aspect
For CBSE class 10th and 12
Have you ever wondered why bees are attracted to flowers? Flowers look beautiful and are fragrant, but there is a reason behind this – flowers actually help plants to reproduce. Flowering plants have seeds, carry the genetic information of the parents and develop into a new plant.
Explore pollination notes provided here to learn about the process and types of pollination.
Table of Contents
Pollination
Process
Types
The process of pollination begins when the pollen grains from the respective flowers lands on the stigma and form a pollen tube with the style length, which connects both the stigma and ovary. After the completion of the pollen tube, the pollen grain starts transmitting sperm cells from the grain to the ovary.
Later the process of fertilization in plants will take place when the sperm cells will reach the ovary and egg cells. The seed is then released from the parent plant and making it able to grow into a plant and continue the reproductive cycle with the use of the pollination method.
Pollination in plants is the process where pollen is transferred from the anther, the male part of a flower, to the stigma, the female part of a flower. Pollen can be transferred to one plant or even a nearby plant so that they can get fertilized and make more flowers. This happens in plants that have flowers called angiosperms.
In this lesson you will learn about :
1) What is Pollination?
2) Types of Pollination
3) Self-Pollination
- Adaptations for Self-Pollination
- Advantages and Disadvantages of Self-Pollination
4) Cross-Pollination
- Adaptations for Cross-Pollination
- Advantages and Disadvantages of Cross-Pollination
5) Agents of Cross-Pollination
- Entomophilous
- Anemophilous
- Hydrophilous
6) Artificial Pollination
I hope this document is helpful to you. Please share the document with your friends if you think this will benefit them. Get ready for the next lesson. Thanks.
Hello our respected institutions and faculties
if you want to buy Editable materials (6 to 12th/Foundation/JEE/NEET/CET) for your institution
Contact me ... 8879919898
*CBSE 6 TO 10 TOPICWISE PER CHAPTER 100 QUESTION WITH ANSWER MATHEMATICS & SCIENCE & SST (Biology,Physics,Chemistry & Social studies)* Editable ms word
# *Neet/JEE(MAINS) PCMB*
# *IIT ( advance) PCM*
# *CET (PCMB) level with Details solutions*
(All jee,neet,advance,cet mcq's Count 1 lakh 50k ) data of all subjects*
*TOPICWISE WISE DPP PCMB NEW PATTERN AVILABLE*
Or also study material for *neet and jee* and *foundation* new Material with solutions
Like
*👉🏽Foundation( Class 6th to 10th) Editable Material Latest Available 👇..*
1. VMC - All Subjects
2. Carrer Point(Kota) - All Subjects
3. Bansal Classes - All Subjects
4. Narayana - All Subjects
5. Mentors - All Subjects
6. Brilliants - All Subjects
7. Resonance - All Subjects
8. Motioniitjee - All Subjects
9. Rao(Kota) - All Subjects
10. Insight - All Subjects
11. Allen - All Subjects
12. FITJEE - All Subjects
13. Abhyas Gurukul - All Subject
14. Parth Ashram - All Subject
Many Other+++
*👉🏽All IIT-JEE & NEET Coachings Editable 📚Study Material Latest Available..👇🏼*
1. Narayana - PCMB
2. Etoos India - PCMB
3. Brilliant- PCM
4.Career Point(Kota) - PCMB
5. Bansal - PCMB
6. Resonance - PCMB
7. Sri Chaitanya - PCM
8. Aakash(Delhi) - PCMB
9. Fitjee - PCM
10. Mastermind - PCMB
11. Mentors - PCB
12. Allen - PCMB
13. Plancess - PCMB
14. VMC - PCM
15. Motioniitjee - PCM
16. Nishith - PCM
17. Arride (Kota) - PCM
18. Rao IIT Acad. - PCM
19. Pulse - PCB
20. Abhyas Gurukul - PCMB
21. Drona - PCMB
22. Active Site - PCMB
23. Vision - PCM
24. Parth Ashram - PCMB
25. Brainsmiths - PCM
26. Infinite - PCM
27. Ekalavya - PCM
28. Trick Based - PCM
...
& Many Other Institute Complete Material Available ++.. Also Editable Books 📚 Available
⬇️⬇️⬇️⬇️⬇️⬇️⬇️⬇️⬇️
👉 *Teaching Notes & PPTs (PCMB Editable) are Available in colourful*
**New material Exchange offer also available **
*Those who want Pls contact us...*
or also have {All Etoos, Akash(i-tutor) Digital, Allen, NeetPrep Digital, neuclion, Neuclius Education ,Plancess, SSC, Airforce, CAT, GATE IIT-JAM, NIMCET, IAS pre + mains (RAS Pre + Mains), UPTET,CTET,STET, vedio lacture *(also KG TO 12th Animated video Lecture Language English & Hindi)*} contact with us........👇
For Sample Massage me .
Explain a) advantage of promoting outcrossing in plants and preventi.pdffasttrackcomputersol
Explain a) advantage of promoting outcrossing in plants and preventing self-fertilization, explain
b) two (2) neat/cool mechanisms you learned on how plants pollinate others. Make sure you
provide enough detail showcasing your understanding of those processes.
Explain a) advantage of dispersing seeds, andexplain b) two (2) neat/cool mechanisms you
learned on how disperse their seeds. Make sure you provide enough detail showcasing your
understanding of those processes.
Solution
Advantages of promoting outcrossing in plants and preventing self-fertilization:
Adding genetic diversity to the species,
It will add resistant to diseases,
It will help in production of hybrid plants and flowers, which keeps the species strong,
It will help in production of large number of viable seeds.
There is a possibility to add new desirable characters,
Yield of crop can be maintained,
It helps in evolution,
Undesirable characters of the plant can be eliminated.
Mechanisms you learned on how plants pollinate others:
1. Imperfect (or unisexual) flowers and monoecy.
The separation of the male sexual part (stamen) and the female part (pistil) into two separate
flowers eliminates intrafloral pollination and favors outcrossing. In monoecy (adj. monoecious),
or monoecism, both imperfect flowers are borne on the same plant.e.g. pumpkin and squash,
melons
2. Imperfect flowers and dioecy.
The natural occurence of individual plants bearing either staminate or pistillate flowers ensures
cross-pollination. This phenomenon is called dioecy (adj. dioecious). e.g. papaya
3. Dichogamy.
Opposite of homogamy, the stamen and the pistil mature at different periods. There are two
main types: protandry and protogyny.
In protandry, the stamens or anthers develop ahead and the pollen grains mature and are shed
before the pistils or the stigma become mature and receptive. Eg: Asteraceae
In protogyny, the pistils or stigma mature ahead of the stamens or anthers. e.g. Suaeda; Simpson
4. Chasmogamy.
Opposite of cleistogamy, pollen is shed, the stigma becomes receptive, and pollination occurs
when the flower opens The opening of the flower exposes the stigma to pollen from other
flowers.
5. Hercogamy (or herkogamy).
This is the spatial separation of the male (stamens) and female (stigma) sexual organs within a
flower. In one type of hercogamy called heterostyly, the heights of stigmas relative to the
stamens vary from flower to flower.
6. Self-sterility or self-incompatibility.
Self-sterility is the inability of a plant to form functional gametes or sexual structures while self-
incompatibility is a condition in which fertilization fails to occur between gametes from the same
individual. In both cases, self-pollination does not form a seed and thus seeds that are formed
necessarily arise from cross-pollination.
ACCORDING TO CHEGG GUIDELINES WE HAVE TO ANSWER ONE QUESTION AT A
TIME. POST THE REST AS SEPERATE QEUSTION, THEN I CAN HELP YOU..
From the forgoing presentation, it can be concluded that breeding characters viz., flowering period, inflorescence, time of flower opening, time of anther dehiscence, time of stigma receptivity, pollinating agent ,time of visitor of pollinating agent and fruit set (%) in tropical species are required to be studied as they are vital for any improvement and eco-environmental planning purposes. It also throws light on how species adopts itself along with the phenomenon of speciation and reproductive isolation. From these characters we can introduce new variety which is essential for further evaluation and also the identification of the interactions between biological factors, such as animal, plant species, and non-biological factors, like temperature, RH, rain and wind, helps us to elaborate management and conservation plans for the ecosystems of the planet, which have become more and more necessary due to highly increased rate of deterioration of different ecosystems during the last few decades.
Micro RNA genes and their likely influence in rice (Oryza sativa L.) dynamic ...Open Access Research Paper
Micro RNAs (miRNAs) are small non-coding RNAs molecules having approximately 18-25 nucleotides, they are present in both plants and animals genomes. MiRNAs have diverse spatial expression patterns and regulate various developmental metabolisms, stress responses and other physiological processes. The dynamic gene expression playing major roles in phenotypic differences in organisms are believed to be controlled by miRNAs. Mutations in regions of regulatory factors, such as miRNA genes or transcription factors (TF) necessitated by dynamic environmental factors or pathogen infections, have tremendous effects on structure and expression of genes. The resultant novel gene products presents potential explanations for constant evolving desirable traits that have long been bred using conventional means, biotechnology or genetic engineering. Rice grain quality, yield, disease tolerance, climate-resilience and palatability properties are not exceptional to miRN Asmutations effects. There are new insights courtesy of high-throughput sequencing and improved proteomic techniques that organisms’ complexity and adaptations are highly contributed by miRNAs containing regulatory networks. This article aims to expound on how rice miRNAs could be driving evolution of traits and highlight the latest miRNA research progress. Moreover, the review accentuates miRNAs grey areas to be addressed and gives recommendations for further studies.
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Venturesgreendigital
Willie Nelson is a name that resonates within the world of music and entertainment. Known for his unique voice, and masterful guitar skills. and an extraordinary career spanning several decades. Nelson has become a legend in the country music scene. But, his influence extends far beyond the realm of music. with ventures in acting, writing, activism, and business. This comprehensive article delves into Willie Nelson net worth. exploring the various facets of his career that have contributed to his large fortune.
Follow us on: Pinterest
Introduction
Willie Nelson net worth is a testament to his enduring influence and success in many fields. Born on April 29, 1933, in Abbott, Texas. Nelson's journey from a humble beginning to becoming one of the most iconic figures in American music is nothing short of inspirational. His net worth, which estimated to be around $25 million as of 2024. reflects a career that is as diverse as it is prolific.
Early Life and Musical Beginnings
Humble Origins
Willie Hugh Nelson was born during the Great Depression. a time of significant economic hardship in the United States. Raised by his grandparents. Nelson found solace and inspiration in music from an early age. His grandmother taught him to play the guitar. setting the stage for what would become an illustrious career.
First Steps in Music
Nelson's initial foray into the music industry was fraught with challenges. He moved to Nashville, Tennessee, to pursue his dreams, but success did not come . Working as a songwriter, Nelson penned hits for other artists. which helped him gain a foothold in the competitive music scene. His songwriting skills contributed to his early earnings. laying the foundation for his net worth.
Rise to Stardom
Breakthrough Albums
The 1970s marked a turning point in Willie Nelson's career. His albums "Shotgun Willie" (1973), "Red Headed Stranger" (1975). and "Stardust" (1978) received critical acclaim and commercial success. These albums not only solidified his position in the country music genre. but also introduced his music to a broader audience. The success of these albums played a crucial role in boosting Willie Nelson net worth.
Iconic Songs
Willie Nelson net worth is also attributed to his extensive catalog of hit songs. Tracks like "Blue Eyes Crying in the Rain," "On the Road Again," and "Always on My Mind" have become timeless classics. These songs have not only earned Nelson large royalties but have also ensured his continued relevance in the music industry.
Acting and Film Career
Hollywood Ventures
In addition to his music career, Willie Nelson has also made a mark in Hollywood. His distinctive personality and on-screen presence have landed him roles in several films and television shows. Notable appearances include roles in "The Electric Horseman" (1979), "Honeysuckle Rose" (1980), and "Barbarosa" (1982). These acting gigs have added a significant amount to Willie Nelson net worth.
Television Appearances
Nelson's char
UNDERSTANDING WHAT GREEN WASHING IS!.pdfJulietMogola
Many companies today use green washing to lure the public into thinking they are conserving the environment but in real sense they are doing more harm. There have been such several cases from very big companies here in Kenya and also globally. This ranges from various sectors from manufacturing and goes to consumer products. Educating people on greenwashing will enable people to make better choices based on their analysis and not on what they see on marketing sites.
Artificial Reefs by Kuddle Life Foundation - May 2024punit537210
Situated in Pondicherry, India, Kuddle Life Foundation is a charitable, non-profit and non-governmental organization (NGO) dedicated to improving the living standards of coastal communities and simultaneously placing a strong emphasis on the protection of marine ecosystems.
One of the key areas we work in is Artificial Reefs. This presentation captures our journey so far and our learnings. We hope you get as excited about marine conservation and artificial reefs as we are.
Please visit our website: https://kuddlelife.org
Our Instagram channel:
@kuddlelifefoundation
Our Linkedin Page:
https://www.linkedin.com/company/kuddlelifefoundation/
and write to us if you have any questions:
info@kuddlelife.org
Natural farming @ Dr. Siddhartha S. Jena.pptxsidjena70
A brief about organic farming/ Natural farming/ Zero budget natural farming/ Subash Palekar Natural farming which keeps us and environment safe and healthy. Next gen Agricultural practices of chemical free farming.
Diabetes is a rapidly and serious health problem in Pakistan. This chronic condition is associated with serious long-term complications, including higher risk of heart disease and stroke. Aggressive treatment of hypertension and hyperlipideamia can result in a substantial reduction in cardiovascular events in patients with diabetes 1. Consequently pharmacist-led diabetes cardiovascular risk (DCVR) clinics have been established in both primary and secondary care sites in NHS Lothian during the past five years. An audit of the pharmaceutical care delivery at the clinics was conducted in order to evaluate practice and to standardize the pharmacists’ documentation of outcomes. Pharmaceutical care issues (PCI) and patient details were collected both prospectively and retrospectively from three DCVR clinics. The PCI`s were categorized according to a triangularised system consisting of multiple categories. These were ‘checks’, ‘changes’ (‘change in drug therapy process’ and ‘change in drug therapy’), ‘drug therapy problems’ and ‘quality assurance descriptors’ (‘timer perspective’ and ‘degree of change’). A verified medication assessment tool (MAT) for patients with chronic cardiovascular disease was applied to the patients from one of the clinics. The tool was used to quantify PCI`s and pharmacist actions that were centered on implementing or enforcing clinical guideline standards. A database was developed to be used as an assessment tool and to standardize the documentation of achievement of outcomes. Feedback on the audit of the pharmaceutical care delivery and the database was received from the DCVR clinic pharmacist at a focus group meeting.
2. The process by which pollen grains are transferred from anthers to stigma is referred as pollination. Pollination is
of two types: viz. 1) Autogamy or self pollination and 2) Allogamy or cross pollination.
I. Autogamy
Transfer of pollen grains from the anther to the stigma of same flower is known as autogamy or self pollination.
Autogamy is the closest form of inbreeding. Autogamy leads to homozygosity. Such species develop
homozygous balance and do not exhibit significant inbreeding depression.
Mechanism promoting self-pollination
1. Bisexuality. Presence of male and female organs in the same flower is known as bisexuality. The presence of
bisexual flowers is a must for self pollination. All the self pollinated plants have hermaphrodite flowers.
2. Homogamy. Maturation of anthers and stigma of a flower at the same time is called homogamy. As a rule,
homogamy is essential for self-pollination.
3. Cleistogamy. When pollination and fertilization occur in unopened flower bud, it is known as cleistogamy. It
ensures self pollination and prevents cross pollination. Cleistogamy has been reported in some varieties of
wheat, barley, oats and several other grass species.
4. Chasmogamy. Opening of flowers only after the completion of pollination is known as chasmogamy. This also
promotes self pollination and is found in crops like wheat, barley, rice and oats.
5. Position of Anthers. In some species, stigmas are surrounded by anthers in such a way that self pollination is
ensured. Such situation is found in tomato and brinjal. In some legumes, the stamens and stigma are enclosed
by the petals in such a way that self pollination is ensured. Examples are greengram, blackgram, soybean,
chickpea and pea.
Mode of pollination
3. II. Allogamy
Transfer of pollen grains from the anther of one plant to the stigma of another plant is called allogamy or cross
pollination. This is the common form of out-breeding. Allogamy leads to heterozygosity. Such species
develop heterozygous balance and exhibit significant inbreeding depression on selfing.
Mechanism promoting cross-pollination
1. Dicliny. It refers to unisexual flowers. This is of two types: viz. i) monoecy and ii) dioecy. When male and
female flowers are separate but present in the same plants, it is known as monoecy. In some crops, the male and
female flowers are present in the same inflorescence such as in mango, castor and banana. In some cases, they
are on separate inflorescence as in maize. Other examples are cucurbits, grapes, strawberry, cassava and
rubber. When staminate and pistillate flowers are present on different plants, it is called dioecy. It includes
papaya, date palm, spinach, hemp and asparagus.
2. Dichogamy. (from the Greek dikho-apart and gamous-marriage) It refers to maturation of anthers and stigma of
the same flowers at different times. Dichogamy promotes cross pollination even in the hermaphrodite species.
Dichogamy is of two types: viz. i) protogyny and ii) protandry. When pistil matures before anthers, it is
called protogyny such as in pearl millet. When anthers mature before pistil, it is known as protandry. It is
found in maize, sugarbeet and several other species.
3. Heterostyly. When styles and filaments in a flower are of different lengths, it is called heterostyly. It promotes
cross pollination, such as linseed.
Distyly: Primose ( Primula vulgaris) – Two types of flowers
1. Pin – eyed or long – styled flowers 2. Thrum- eyed or short- styled flowers
Tristyly: ex. Lythrum and Oxalis
5. 4. Herkogamy. Hinderance to self-pollination due to some physical barriers such as presence of
hyline membrane around the anther is known as herkogamy. Such membrane does not allow the
dehiscence of pollen and prevents self-pollination such as in alfalfa.
5. Self incompatibility: The inability of fertile pollens to fertilize the same flower is referred to as
self incompatibility. It prevents self-pollination and promotes cross pollination. Self
incompatibility is found in several crop species likeBrassica, Radish, Nicotiana, and many grass
species. It is of two types sporophytic and gametophytic.
6. Male sterility: In some species, the pollen grains are non functional. Such condition is known as
male sterility. It prevents self-pollination and promotes cross pollination. It is of three types:
viz. genetic, cytoplasmic and cytoplasmic genetic. It is a useful tool in hybrid seed production.
Study of floral biology and aforesaid mechanisms is essential for determining the mode of
pollination of various crop species. Moreover, if selfing has adverse effects on seed setting and
general vigour, it indicates that the species is cross pollinated. If selfing does not have any
adverse effect on these characters, it suggests that the species is self-pollinated.
The percentage of cross pollination can be determined by growing a seed mixture of two different
varieties together. The two varieties should have marker characters say green and pigmented
plants. The seeds are harvested from the recessive (green) variety and grown next year in separate
field. The proportion of pigmented plants in green variety will indicate the percentage
of outcrossing or cross pollination.
6. Significance of pollination
The mode of pollination plays an important role in plant breeding. It has impact on five important aspects : viz.
1) gene action 2) genetic constitution 3) adaptability 4) genetic purity and 5) transfer of genes.
17. A flowering twig of Ophrys speculum, pollinated by hairy wasp, Colpa aurea.
18. Humming birds, sun-birds
and honey –eaters most
visiting birds
Eg. Strelitzia reginae by sun-
birds
Ornithophily
19. Cheiropterophily
•Occurs only in tropics
•Eidolon helvum, vegetarian bat- visits the flowers of Adansonia digitata to
extract nectar
• In Kigelia africana, pollination by micropteris pusillus