Photosynthesis (G.K. photo–light synthesis-production) is the anabolic process in which green plants produce their food in the presence of sunlight and chlorophyll and produce glucose and oxygen. The volume of oxygen. Released photosynthesis is coequal to the volume of carbon dioxide absorbed. The released oxygen is exclusively formed from water and not from carbon dioxide. The process of photosynthesis can be represented by the following chemical equation.
the overall reaction is not a single and simple reaction between carbon dioxide and water but a highly complex process in which a number of reactions occur. in it radiant energy absorbed by chlorophyll is transferred into chemical energy which is available for all vital activities of living cells. photosynthesis consists of oxidation. the overall process of photosynthesis is
- Light reaction or hill reaction.
- dark reaction or Blackman
Factors Affecting photosynthesis
Like another physiological process, photosynthesis is also affected by a number of factors. these factors are
- Temperature: When CO2, like and other factors are not limiting, the rate of photosynthesis increases with a rise in temperature, over a range from 6°C. to about 37°C. above this temperature, there is an abrupt fall in the rate and the tissue dies at 43°C, high temperatures cause the inactivation of enzymes and therefore affect the enzymatically controlled dark reaction of photosynthesis.
- Carbon Dioxide concentration: Nearly 0.0325% by volume of CO2 is present in the atmosphere and this low level it acts as a limiting factor. Under laboratory conditions when light and temperature are not limiting factors, an increase in CO2 concentration in the atmosphere from 0.03%-1% raises the rate of photosynthesis.
- Light: the photosynthesis active region of the spectrum of light is at a wavelength from 400-700nm. Greenlight (550nm) plays an important role in photosynthesis. Light supplies energy for the process. Light varies in intensity, quality, and duration.
- The concentration of oxygen: O2 has been shown to inhibit photosynthesis in C3 plants while C4 plants show little effect. It is suggested that C4 plants have photorespiration and high O2 stimulates it. The rate of photosynthesis increases by 30-50% when the concentration of O2 in the air is reduced from 20-0.5% and CO2 light and temperature are not limiting factors.
- Water: Water is an essential raw material in carbon assimilation. Less than 1% of the water absorbed by a plant is used in photosynthesis. The decreases in water contents of the soil from field capacity to the permanent wilting point results in the decreased photosynthesis.
- Minerals Elements: Several minerals are essential for plant growth. These include Mg, Fe, Cu, Cl, Mn, P and are closely associated with reactions of photosynthesis.
- Air pollutants: Gaseous and metallic pollutants decrease photosynthetic activity. These include ozone, SO2, Oxidants, hydrogen fluorides, etc.
- Chlorophyll Content: Chlorophyll is one of the important essential components required for the process of photosynthesis. It always takes place in a green part of plants but never in non-green parts.
- Anatomy of Photosynthetic parts: The rate of photosynthesis gets influenced greatly by the structure of photosynthetic parts. Just like the thickness of cuticle and epidermis, and distribution of stomata, chlorophyllous and non-chlorophyllous mesophyll tissues, etc. influence the rate of photosynthesis.
- Age of Leaf: The rate of photosynthesis increases up to the maturation of the leaf. But the rate of photosynthesis may decrease in an aging leaf.