Environmental factors influencing growth

(1) Light

• Indirectly： by photosynthesis and transpiration.
• Directly： A little flux of light can control the morphogenesis of the plant.

(2) Temperature—Three cardinal points:

• minimum, optimum, and maximum temperature for growth”
• optimum temperature for growth is the temperature at which a plant grows fastest but not strongest.
• The suboptimum temperature for growth is the temperature at which a plant grows slower strongest than at the optimum temperature.

(3). Water

• “Dry for root, wet for bud”. Root depends on cell division and bud does cell elongation.

(4) O2: enough O2 favors growth. 10-15% soil O2——tilling

(5). Mineral nutrition: Grow worse upon deficiency or toxification