Plant Growth and Development Overview

Overview of Plant Growth and Development

• Plant growth involves size increase, cell division, and cell enlargement; development refers to growth, differentiation, and maturation of cells, tissues, and organs.
• Both processes are regulated by genetics, environmental factors, and hormones.

Key Concepts in Plant Growth

• Growth

  • Measured by increases in height, leaf area, root length, or biomass.
  • Influenced by internal genetics and external conditions like light, water, temperature, and nutrients.

• Development

  • Progresses from germination to maturity involving the formation of roots, stems, leaves, and flowers.
  • Controlled by hormones and environmental factors including temperature, light, and water availability.

• Morphogenesis

  • Biological process responsible for developing plant shape and structure from the embryo.
  • Defines the mature plant architecture through differentiation of leaves, roots, and stems.

• Life Cycle

  • Includes all stages from seed to reproduction and eventual death.
  • Key stages: germination, vegetative growth, flowering, pollination, seed formation, and seed dispersal.

Stages of Plant Growth

• Embryogenesis

  • Begins at fertilization, transforming the zygote into a seedling with roots, shoots, and cotyledons.
  • In dicots, results in two embryonic leaves; in monocots, results in one.

• Seed Germination

  • Consists of three phases:
    • Imbibition: Seed absorbs water, swells, and activates digestive enzymes.
    • Dormant: Breakdown of stored food into simpler sugars to support growth.
    • Growth: Mature seedling develops, strengthens its structure, and prepares for flowering.

• Vegetative Development

  • Focuses on growth of non-reproductive plant parts (roots, stems, leaves).
  • Involves cell division and elongation influenced by light, water, and nutrients.

• Reproductive Development

  • Involves flower, fruit, and seed production critical for species survival.
  • Influenced by photoperiod, temperature, and water availability.

Mechanisms of Plant Growth and Development

• Control Mechanisms

  • Regulated by hormones like auxins, gibberellins, cytokinins, abscisic acid, and ethylene.
  • Hormones influence cell division, elongation, flowering, fruiting, and aging processes.

• Regulation

  • Manages plant growth rates and developmental stages for optimal survival.
  • Internal signals (hormones) and external cues (environmental conditions) guide adaptations (e.g., slowing growth during drought).

• Adaptation

  • Plants undergo changes to survive environmental challenges (structural, physiological, biochemical).
  • Examples include developing thicker leaves for drought resistance or altered growth patterns in response to temperature changes.

Key Factors Influencing Plant Growth

• Environmental Factors
  • Light: Vital for photosynthesis; duration affects flowering and development.
  • Water: Necessary for photosynthesis, nutrient transport, and overall plant health.