RELEVANCE – UPSC GS PRELIMS & GS MAINS –III
First go through the text (given after the questions) and then attempt the questions.
UPSC PRELIMS 2018
QUES . Which of the following statements best describes “carbon fertilization”?
(a) Increased plant growth due to increased concentration of carbon dioxide in the atmosphere
(b) Increased temperature of Earth due to increased concentration of carbon dioxide in the atmosphere
(c) Increased acidity of oceans as a result of increased concentration of carbon dioxide in the atmosphere
(d) Adaptation of all living beings on Earth to the climate change brought about by the increased concentration of carbon dioxide in the atmosphere
ABOUT CARBON FERTILIZATION
The enhancement of the growth of plants as a result of increased atmospheric CO2 concentration is known as carbon fertilization .
The atmospheric carbon-dioxide concentration has been rapidly rising since 1959 . If such rising trend continues, by the end of twenty first century the atmospheric concentration of CO2 shall increase to a level between 540 and 970 ppm.
Depending on their mechanism of photosynthesis, certain types of plants are more sensitive to changes in atmospheric CO2 concentration.
Positive effects of increased CO2 on plants
More growth in C3 plants
When the CO2, concentration of the atmosphere is more or less doubled, the growth of many plants i.e., C3 plants in particular, under favourable conditions of water, nutrients, light and temperature, could increase by about thirty per cent on average, in the short term of few years or so.
Plants could grow in regions of water scarcity
Due to increased carbon-dioxide concentration, the rate of photosynthesis also increases, and the stomatal conductance decreases due to partial closure of stomata. Hence, the transpiration rate reduces, and water-use efficiency increases. Such effect allows many species to grow successfully in regions of water scarcity.
Plants could grow in poor soils
Under higher atmospheric carbon dioxide concentrations, plants allocate, a greater proportion of photosynthate to roots. However, greater root production increases development of mycorrhiza and fixation of nitrogen in root nodules, thus, makes possible the plants to grow in soils which are poor in nutrition.
Negative effects of increased CO2 on plants
However, in natural conditions the beneficial effects of increased carbon dioxide may not be there because of negative effects of global warming.
There is no real-world situation, in which only CO2 increases, all else remaining equal. Those other effects of increased atmospheric CO2, namely increased temperatures and altered moisture regimes, generally have adverse effects on growth.