Detailed Summary
Growth is a key characteristic of living organisms, defined as an irreversible increase in size that can be measured through fresh weight, dry weight, length, area, volume, and cell number. Plant growth is particularly unique due to its indeterminate nature, allowing plants to grow continuously throughout their lives, primarily thanks to meristems located at various sites in the plant.
Phases of Growth
Growth can be divided into three main phases:
1. Meristematic Phase: This phase consists of actively dividing cells rich in protoplasm, located in areas like root and shoot apices.
2. Elongation Phase: Cells begin to elongate, leading to an increase in size and volume.
3. Maturation Phase: Cells achieve full size and become specialized to perform specific functions.
Growth Measurement
Measuring growth typically involves parameters such as length, area, or cell number due to the difficulty in quantifying protoplasm directly. Two types of growth rates are discussed: arithmetic, where one daughter cell divides while the other differentiates, and geometric, where both retain the ability to divide, leading to exponential growth. These growth rates can be captured through sigmoidal curves, demonstrating various growth stages.
Conditions for Growth
Crucial conditions for plant growth include the availability of water, oxygen, nutrients, and an optimal temperature range. Environmental factors like light also contribute to different growth and development stages.
Understanding these aspects of growth sets the foundation for comprehending plant differentiation and development in subsequent sections.