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PLANT GROWTH AND DEVELOPMENT

  • PREPARE BY ITI MERAWI PGT BIOLOGY JNV DONGARGARH DIST- RAJNANDGAON ,CG

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CONTENT

  • INTRODUCTION
  • GROWTH
  • DIFFERENTIATION, DEDIFFERENTIATION AND REDIFFERENTIATION
  • DEVELOPMENT
  • PLANT GROWTH REGULATOR
  • PHOTOPERIODISM
  • VERNALISATION
  • SEED DORMANCY

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INTRODUCTION

  • All cells of a plant develops from the zygote.
  • Zygote produces a number of cells which orgnize in to tissues and organs
  • Development is the sum of two processes growth and differentiation.
  • During the process a complex body organisation is formed that produces root, leaves, branches, flower ,fruit ,and seeds and eventually they die

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GROWTH

  • Growth can be defined as an irreversible permanent increase in size of an organ or its parts or even of an individual cell.
  • Growth is accompanied by metabolic processes (both anabolic and catabolic), that occur at the expense of energy. Therefore, for example, expansion of a leaf is growth.

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FEATURE OF GROWTH

  • CELL DIVISION
  • CELL ELONGATION
  • CELLULAR DIFFERENTIATION

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GROWTH RATE

  • The increased growth per unit time is termed as growth rate.
  • The rate of growth can be expressed mathematically
  • Type of growth rate
  • GROWTH RATE

ARITHMETIC GROWTH

GEOMATRIC

GROWTH

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ARITHMATIC GROWTH

      • After mitotic cell division only one daughter cell continues to divide while the other differentiates and matures
  • Example – root elongating at constant rate

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Mathematical expression

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GEOMATRIC GROWTH

  • Initial growth is slow (lag phase ), followed by a rapid increase in growth (log /exponential phase ),and followed by a phase where growth slow down (stationary phase)

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MATHEMATICAL EXPRESSION

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ABSOLUTE AND RELATIVE GROWTH RATE

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DIFFERENTIATION,DEDIFFERENTIATION,REDIFFERENTION�

  • The cell derived from root apical and shoot apical meristem and cambium differentiate and mature to perform specific function.This act leading to maturation is termed as differentiation.
  • The living differentiated cells,that by now have lost the capacity to divide under certain condition.This phenomenon is termed as dedifferentiation.
  • Tissue once again loose the capacity to divide but mature to perform specific function get redifferentiation.

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DEVELOPMENT

  • Development is a term that includes all changes that an organism goes through during its life cycle from germination of the seed to senescence.

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  • Sequence of the developmental process in plant cell

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PLANT GROWTH REGULATOR

  • Plant growth regulators are chemical substance that influence the growth and differentiation of plant cell,tissue and plant parts.
  • It function as chemical messenger for intercellular communication.
  • It perform growth and development by coordinating to eachother

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PHYTOHARMONES

  • Auxin
  • Gibberllins
  • Cytokinins
  • Abscisic acid
  • Ethyline

GROWTH PRAMOTAR

GROWTH INHIBITOR

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AUXIN

  • IAA,IBA isolated from plant but NAA, 24-D are synthetic harmones
  • F.W.Went isolated auxin from the tip of coleoptiles of oat seedlings.
  • Auxin were discovered by Charles Darwin and Francis Darwin.

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FUNCTION OF AUXIN

  • Promote apical dominance
  • Initiate rooting in stem cutting
  • Prevent fruit and leaf drop at early stages
  • Induce parthenocarpy
  • Pramote abscission of older mature leaves and fruits
  • It perform as weedicides in monocot crop plants

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GIBBERLLINS

  • A Japanese scientist E Kurosawa identified gibberellins present in a fungal pathogen Gibberella fujikuroi.
  • It is isolated from infected rice seedling when treated with sterile filterate of fungus
  • It is isolated in the form of GA1,GA2,GA3.

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FUNCTION OF GIBBERELLINS

  • Elongation of stem
  • Bolting of rosette plants
  • Seed germination
  • Overcome the natural dormancy of bud,tubers,seeds

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CYTOKININS

  • It is discovered by Skoog and Millar.
  • They crystallised the cytokinesis pramoting active substance named it kinetin from corn-kernels and coconut milk.

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FUNCTION OF CYTOKININ

  • Delay the senescence of leaves,flower,fruit
  • It pramote lateral budding
  • It induce cell division

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ABSCISIC ACID

  • Frederick T. Addicott and his coworker identified Abscisic acid.
  • ABA was isolated from several abscission –accelerating substance from cotton plants
  • It is called stress harmones

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FUNCTION OF ABA

  • It is plant growth inhibitor
  • It induce seed and bud dormancy
  • It inhibit seed germination
  • Stimulate closure of stomata

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ETHYLENE

  • Causins confirmed the release of a volatile substance from ripened oranges that hasten the ripening of stored unripened bananas
  • The volatile substance was identified as ethylene.

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FUNCTION OF ETHYLENE

  • Pramote senescence and abscission
  • Inhibit elongation of stem roots
  • Induce fruit ripening
  • Break seed and bud dormancy
  • Initiate germination in peanut seeds

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PHOTOPERIODISM

  • Photoperiodism is the response of plants to the relative lengths of dark and light periods.
  • Some plants require periodic exposure to light to induce flowering.
  • Some plant require dark period to induce flowering

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VERNALISATION

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SEED DORMANCY

  • A resting period when seeds undergo no growth and have reduced cell activity or metabolism

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REFERENCE

  • NCERT Biology class XI
  • www.google.com
  • wikkipedia.com

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THE END