Effect on Carbon Dioxide Fertilization in Plants

The increasing abundance of greenhouse gases in the atmosphere has the following three main effects:

(i) CO2 fertilisation effect on plants

(ii) Global warming and

(iii) Depletion of ozone (O3) layer in the stratosphere.

Carbon dioxide (CO2) Fertilisation Effect on Plants:

The data produced in USA have shown that atmospheric carbon-dioxide concentration has been rapidly rising since 1959 as shown in the graph. 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.

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.

The response of plants to elevated concentrations of CO2, is called carbon dioxide fertilisation effect.

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.

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.

However, in natural conditions the beneficial effects of increased carbon dioxide may not be there because of negative effects of global warming.