Factors Influencing Growth

1. Nutrient supply

• Green plants require several mineral ions and other essential elements for normal growth and development
• These nutrients come from the soil for manufacturing of food
• Growth ceases when the nutrient supply becomes limiting.

2. Water

• Water is a medium for all chemical reactions and physiological processes.
• Water is essential for photosynthesis
• Early growth which is due to the turgid conditions of the cells requires plenty of water
• Under conditions of water scarcity, plant growth is severely impaired
• On the other hand, excess of water in the soil may cause water logging, resulting anaerobic conditions in the roots whose growth is severely affected

3. Oxygen

• Oxygen is necessary for cellular respiration in the plants
• Food materials are broken down in the process of respiration and energy is released in the form of ATP molecules
• This is the utilizable form of energy for the living cells
• This energy is used for various activities of the cell and directly take part in the growth processes

4. Temperature

• Temperature also affects growth directly or indirectly, though growth occurs between the temperature of 4 °C to 45 °C
• Most plant species prefer temperature in the range of 20°C to 40°C
• At optimum temperature enzymes activity also become optimum
• Low temperature during night time reduces the rate of respiration and high temperature during day time increase photosynthesis activity
• Very low temperature causes freezing and chilling injury to many plants

5. Light

• Intensity of light, quality of light and duration of light affect the plant growth and development
• Light has great morphological effect on the leaves and stems of the plants
• Plants growing in darkness are characterzied by long, succulent weak stems
• The leaves become underdeveloped, pale, yellowish, chlorophyll deficient
• This is called etiolating variations in the intensity, quality and duration of light variously affect seed germination and flowering in different plants
• The effect of light on reproductive growth is called Photoperiodism

6. Growth regulators

• These are, otherwise, known as hormones, phyto hormones or bio regulators
• These have pronounced effect on the growth of the plants