Conditions for Growth

Growth in plants depends on a combination of environmental and physiological conditions acting together. Water is essential both as a component of protoplasm and to maintain the turgidity that drives cell enlargement; it also serves as the medium in which biochemical reactions of metabolism take place. A steady supply of nutrients -- both the microelements and macroelements described later in the chapter (Section 7.12) -- is equally essential for normal growth. Temperature must remain within an optimum range, generally between 25 degrees C and 35 degrees C, outside of which growth processes slow down or stop. Oxygen is required for respiration, which releases the energy that powers growth. The ratio of carbon to nitrogen available to the plant also influences the balance between vegetative and reproductive growth. Light is essential both for seed germination and for photosynthesis, which supplies the organic material growth is built from. Finally, gravitational force he …