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13. PLANT GROWTH AND DEVELOPMENT

The chapter focuses on plant growth and development, highlighting the processes of growth, differentiation, and their interrelation. It discusses the phases of growth, the role of meristems, and the impact of environmental factors and plant growth regulators (PGRs) on plant physiology. The chapter emphasizes the significance of both intrinsic and extrinsic factors in achieving optimal growth outcomes in plants.

Sections

PLANT GROWTH AND DEVELOPMENT

This section discusses the processes of plant growth, differentiation, and development, along with the intrinsic and extrinsic factors that influence these processes.

13 Section Overview

Start current section content and materials

13.1 Growth

This section covers the fundamental concept of plant growth, its measurement, phases, and the intrinsic and extrinsic factors influencing it.

13.1.1 Plant Growth Generally is Indeterminate

Plants exhibit indeterminate growth, facilitated by the presence of meristems, allowing for continuous addition of new cells throughout their life.

13.1.2 Growth is Measurable

Growth in plants is an irreversible increase measured through various parameters such as weight, length, and cell number.

13.1.3 Phases of Growth

Plant growth is categorized into three main phases: meristematic, elongation, and maturation, each characterized by specific cellular and structural changes.

13.1.4 Growth Rates

Growth rate measures the increase in size or number of organisms over time, which can be classified as arithmetic or geometric.

13.1.5 Conditions for Growth

This section discusses the essential conditions that facilitate plant growth, including water, nutrients, oxygen, temperature, and environmental signals.

13.2 Differentiation, Dedifferentiation and Redifferentiation

This section discusses the processes of differentiation, dedifferentiation, and redifferentiation in plants, highlighting their significance in plant growth and the functional specialization of cells.

13.3 Development

Development encompasses all changes an organism undergoes from seed germination to senescence, integrating growth and differentiation.

13.4 Plant Growth Regulators

This section discusses the characteristics, discovery, and physiological effects of plant growth regulators (PGRs), highlighting their roles in plant development and responses to environmental factors.

13.4.1 Characteristics

Plant growth regulators are crucial small molecules that control various growth and developmental processes in plants.

13.4.2 The Discovery of Plant Growth Regulators

The discovery of plant growth regulators unfolded through a series of accidental findings related to plant behavior and physiology.

13.4.3 Physiological Effects of Plant Growth Regulators

This section discusses how various plant growth regulators (PGRs) influence plant growth, development, and physiological processes.

13.4.3.1 Auxins

Auxins are plant hormones that play a crucial role in regulating growth and developmental processes in plants.

13.4.3.2 Gibberellins

Gibberellins are crucial plant growth regulators that promote growth, mainly by stimulating stem elongation and influencing various developmental processes.

13.4.3.3 Cytokinins

Cytokinins are plant growth regulators that play a crucial role in promoting cell division and influencing various growth and developmental processes in plants.

13.4.3.4 Ethylene

Ethylene is a gaseous plant growth regulator that influences various physiological processes including fruit ripening, senescence, and abscission.

13.4.3.5 Abscisic Acid

Abscisic acid (ABA) is a crucial plant growth regulator involved in growth inhibition, stress response, and seed dormancy control.

13.5 SUMMARY

Growth in plants is an irreversible increase in size and complexity, influenced by both internal and external factors, including plant growth regulators.

13.6 EXERCISES

This section presents exercises related to plant growth, differentiation, and development, focusing on key concepts and terms.

Learning Objectives

  • Growth is an irreversible increase in size and can be measured in various parameters.

  • Plants have distinct phases of growth: meristematic, elongation, and maturation.

  • Plant growth regulators play a crucial role in regulating growth and development processes.

Key Concepts

Growth

An irreversible permanent increase in size of an organ or an individual cell.

Differentiation

The process by which cells mature to perform specific functions.

Dedifferentiation

The process where mature cells regain the ability to divide.

Redifferentiation

The process by which dedifferentiated cells mature again into specialized cells.

Meristem

Regions of plant tissues that are capable of cell division and contribute to growth.

Plant Growth Regulators (PGRs)

Chemical substances that regulate physiological processes in plants.

Practice Exercises

Total Questions

3

Estimated Time

6 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting