Friday, 1 April 2016


Effect of climate change.

Sushree Shailani Suman

 1- Perishing green plants: Is global warming the cause?
Global warming is a growing concern worldwide with climate change being the most talked subject. Its effects are well known on plants and the photosynthetic process. The increased concentration of heat-trapping greenhouse gases such as carbon dioxide (CO2) and methane (CH4) has accelerated global warming in manifold and led to extreme events such as cyclonic storms, typhoons, drought, unseasonal rainfall, and heat waves.
2- How do plants deal with global warming?
The most surprising fact about CO2 is its ability to increase the rate of photosynthesis in green plants, particularly the C3 plants. Through photosynthesis, green plants absorb CO2 from the atmosphere and subsequently convert it into organic products (like carbohydrates, lipids, proteins, etc.) and byproducts (like oxygen). This process has been considered as a source of carbon dioxide sequestration. 
Elevated atmospheric CO2 levels lead to temperature rise with a concomitant increase in the rate of transpiration by the green plants. However, if the plant responds by stomatal closure, the rate of transpiration may decrease. This does not allow excess CO2 to enter the plant and results in an increased survival rate during water scarcity. The advantages are time bound. This also has several adverse effects on the photosynthetic process as absorption of less CO2 means stunted growth. Closed stomata for a longer duration may lead to starvation in plants. Due to less partial pressure of CO2, the stomata will be left open, resulting in rapid water loss along with CO2 intake. Subsequently, the plants wither, wilt and die, which may have huge social implications.
The decomposition of organic matter in the soil is also stimulated by the increased CO2 levels to be easily made available for the plants’ absorption, which in turn increases the rate of photosynthesis and carbon fixation.
Apart from the above-mentioned facts, the enhanced level of CO2 is also marked by increased plant growth that might sound good to the farmers. Conversely, the weeds surrounding the vegetation tend to grow at a faster rate in such environmental conditions.
But such responses by the photosynthetic plants are dependent on diverse environmental factors such as availability of water, moisture content of the soil, nutrient content, atmospheric temperature, and variable CO2 concentration, etc. Responses may be negative or positive depending on the exact nature of changes and the factors that initially limited the growth and rate of photosynthesis.


Green revolution and its loopholes

Sushree Shailani Suman

1- Green Revolution for Mass: The advanced Mexican agricultural technology introduced by Norman Borlaug made a way out for the evolutionary technology in India, which was initiated as a trial project by Dr. M.S. Swaminathan in the northern states of India, especially Punjab and Haryana. The technology received various approbations from the scientific circles: “Green revolution describes the spectacular increase that took place during 1967–1978, and is continuing in the production of food grains in India”- was cited by J.G. Harrar.

2- Advancements: Green revolution proved to be a track changer in the traditional farming techniques (introduction of tractors, thrashers, harvesters; use of chemical fertilizers, pesticides, herbicides, for instant increase in the yield, etc.) as well as replacing the traditional seeds with high yielding varieties or seeds with genetic superiority.

3- Prolonged Loopholes: Apart from the advantages, green revolution proved to be a bane in disguise for the farmers. It has over burdened them with the increasing costs of chemical fertilizers, pesticides as well as other chemicals. The technology aimed at increasing the production of only the staple cereal crops, like rice and wheat, that too only in the north Indian states. The technology was not well implemented or did not give a proceeding result in many parts of the country.

The genetically superior seeds demanded more water, fertilizers and other accessory chemicals, for their growth and development. The overuse of these chemical ingredients has led to the detoriation and deformation in the chemistry and structure of the soil. The natural soil microbiotas are kept aloof of the soil organic carbon content, which is their nutrition source. The unavailability of the soil carbon leads to a decrease in the concentration of the beneficial soil microbiota that plays an important role in maintaining the structure of the soil. Due to this, the soil particles are left apart and they become compact and lose the water holding capacity.

The depletion in the soil organic carbon leads to the decrease in the soil’s buffering capacity that in turn affects the pH level of the soil. Lowering in the pH level affects various parameters like the unavailability of phosphorus, magnesium, calcium, which in turn affects the physiology of the plants; stunted growth of the plants, decreased root biomass and length, etc. whereas high pH level leads to a decrease in the availability of micronutrients like copper, zinc, boron, etc., which also affects the overall growth and developmental process of the plant. Decrease in the buffering capacity also leads to an increase in the thatch layer, which in turn aggravates the pathogenic population in the soil. In order to kill these pathogens, it is needed to use chemicals that, on the contrary, kill the beneficial organisms in the soil too.

Apart from these drawbacks, the technology of green revolution has neither proved to be a long-term solution, nor has it ensured food security for the rising population of our country.


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