Plant Growth and Development

Plant Growth and Reproduction

Vegetative Growth

• Allows plants to increase in size and biomass
• Occurs through the production of new cells in meristematic regions (apical and lateral)
• Types of vegetative growth:
  • Primary growth: occurs at the tips of stems and roots, increases plant height and depth
  • Secondary growth: occurs in woody plants, increases stem and root diameter

Cell Division and Differentiation

• Cell division: occurs in meristematic regions, resulting in new cells
• Cell differentiation: new cells mature and specialize into different cell types (e.g., xylem, phloem, epidermis)
• Hormones regulate cell division and differentiation, promoting growth and development

Hormonal Regulation

• Plant hormones (e.g., auxins, gibberellins, cytokinins, ethylene) regulate growth and development
• Auxins (e.g., IAA) promote cell elongation and differentiation
• Gibberellins promote stem elongation and seed germination
• Cytokinins promote cell division and differentiation
• Ethylene promotes fruit ripening and senescence

Environmental Factors

• Light: affects phototropism, promoting stem elongation towards light sources
• Temperature: affects growth rate, with optimal temperatures varying among plant species
• Water: essential for growth, with drought limiting growth and reproduction
• Nutrients: essential macronutrients (e.g., N, P, K) and micronutrients (e.g., Fe, Zn) support growth and development

Plant Growth and Reproduction

Vegetative Growth

• Plants increase in size and biomass through vegetative growth
• New cells are produced in meristematic regions, which include apical and lateral regions
• Two types of vegetative growth:
  • Primary growth: occurs at stem and root tips, increasing plant height and depth
  • Secondary growth: occurs in woody plants, increasing stem and root diameter

Cell Division and Differentiation

• Cell division occurs in meristematic regions, resulting in new cells
• New cells mature and specialize into different cell types, such as xylem, phloem, and epidermis
• Hormones regulate cell division and differentiation to promote growth and development

Hormonal Regulation

• Plant hormones regulate growth and development, including:
  • Auxins (e.g., IAA): promote cell elongation and differentiation
  • Gibberellins: promote stem elongation and seed germination
  • Cytokinins: promote cell division and differentiation
  • Ethylene: promotes fruit ripening and senescence

Environmental Factors

• Light affects plant growth, promoting:
  • Phototropism: stem elongation towards light sources
• Temperature affects growth rate, with optimal temperatures varying among plant species
• Water is essential for growth, with drought limiting growth and reproduction
• Nutrients are essential for growth and development, including:
  • Macronutrients: N, P, K
  • Micronutrients: Fe, Zn

Plant Reproduction

Flowering

• Flowers contain reproductive organs and are composed of four main parts: sepals, petals, stamens, and carpels.
• Sepals protect the flower bud, while petals attract pollinators.
• Stamens produce pollen, which contains male reproductive cells.
• Carpels contain ovules, which contain female reproductive cells.

Pollination

• Pollination is the transfer of pollen from the anther to the stigma, allowing fertilization to occur.
• There are two main types of pollination: self-pollination (within the same flower or plant) and cross-pollination (between different flowers or plants).
• Pollinators include insects (bees, butterflies, moths), animals (birds, bats), and wind.

Fruit Formation

• Fruit formation occurs when the ovary of a flower develops into a fruit, which contains seeds.
• Fruits are formed from the ovary wall and can be classified as simple fruits (e.g., bananas), aggregate fruits (e.g., raspberries), or composite fruits (e.g., pineapples).

Vegetative Propagation

• Vegetative propagation is the process by which plants produce new individuals from vegetative parts (leaves, stems, roots).
• Methods of vegetative propagation include leaf cuttings, stem cuttings, root division, and layering.

Growth and Asexual Reproduction

• Growth refers to the increase in size and complexity of a plant.
• Asexual reproduction is the production of new individuals from vegetative parts without the involvement of gametes (sex cells).
• Types of asexual reproduction include the formation of rhizomes (e.g., ginger, potatoes), tubers (e.g., potatoes), bulbs (e.g., onions, garlic), and runners (e.g., strawberries).