Air Pollution and agriculture
The ubiquitous dispersion of pollutants and invasive by-products in the atmosphere is deemed to have a telling impact on the concept of agriculture; long term culpabilities of which sadly amount to destruction of the means to sustain livelihood, by way of floral and faunal deterioration. An assortment of symptoms ranging from certain indicative markings on the foliage and a gradual decline in the health status of the existing crop is often witnessed by major and irreversible crop failure. .
Increased urbanization and industrialization has compromised on the integral quality of air that facilitates plant growth by polluting it. While pollutants are defined as substances which in optimal concentrations produce a measurable effect on plant and animal life, they are broadly classified into either local or widespread based on their prevalence. Consequences of air pollution resulting in visible plant injury and reduced crop yields have been documented in many industrialized nations. .
The damages caused by air pollutants can be either acute resulting in necrosis of the leaf tissues or chronic where it slowly starts with the yellowing or chlorosis of the leaf. They may even go unnoticed due to lack of any visible manifestations and can be discerned only by means of impairment of growth or other physiological alterations like inferior quality biomass. While the damage caused by each pollutant is unique and indicative of the cause, it requires considerable knowledge and observation to appreciate the changes brought forth in order to facilitate restoration of crop health. .
Some of the pollutants creating crop failure include ozone, sulphur dioxide, nitrogen oxides, fluorides, ammonia and ethylene. These pollutants are known to cause cell damage and tissue regeneration due to structural and chemical cellular changes and altered enzyme and hormonal mechanisms resulting in stunted growth and hampered production. Apart from these, the suspended particulate matter in the atmosphere creates no lesser havoc by impairing respiration and photosynthesis mechanisms within the leaf. .
Ironically while air pollution has a marked impact on agriculture, agriculture operations are often claimed to affect air quality through emission of nitrogen compounds, particulate matter and other substances. .
The various crop breeding programmes aimed to boost production have the propensity to increase stomatal conductance for enhanced CO2 assimilation, which may inadvertently increase pollutant intake as well. Various studies conducted to investigate the consequences of air pollution on the existing crop has resulted in the calculation of dose-response relationships for individual pollutants against various crop species. This has led to the formulation of appropriate emission abatement policies for facilitating greater control over this menace of air pollution.