Effect of Various Concentrations of Sulphur Dioxide Pollution on Chlorophyll Pigment of Pisum sativum L. (PEA)

The undesirable changes in composition of environment regarding the physical, chemical and biological characteristics of air, soil and water is known as pollution. The air pollutants include CO, NOx and SO₂. Out of these gases sulphur dioxide is a major air pollutant. It is an acidic in nature. It is colorless and soluble in water. The melting point of sulphur dioxide is -72^oC while the boiling point is - 10^oC. Sulphur dioxide is really offensive and overpowering in its odour. The burning of fossil fuels produces sulphur dioxide, a significant phytotoxic and oxidation of sulphur containing raw materials (Iqbal, M. et al., 2015). The SO₂ dissolves quickly in water and, because to this features it forms sulphuric acid. This sulphuric acid comes on earth in the way acid rain is formed. The acid rain was a major cause of harmful for natural as well as crop vegetation’s. The Sulphur dioxide present on leaf surface enters in to leaves through stomata. When it reaches to leaf tissue and gets converted into sulphite ions and these product affect the metabolism of plant resulting to the plant damage. The sulphuric acid has deleterious effects on growth, productivity, morphology and photosynthetic pigments of plants. After entering in to leaves the Sulphur dioxide ends up in the cells of the mesophyll plant. It has The buildup of sulphur dioxide in chlorophyll cells leads to both short-term and long-term damage. Acute damage alters metabolism, which in turn causes interveinal or marginal necrosis. Plants experience persistent harm from concentrations of SO₂.

In their study, Verma and Agrawal (2000) found that photosynthetic pigments in wheat decreased as a result of the combined effects of SO2 and mineral nutrient availability on wheat output. Results showed that Raphanus sativus chlorophyll-a and chlorophyll-b concentrations, as well as the chlorophyll a/b ratio, were significantly reduced after exposure to SO2. Published by Govind et al. in 2002.    The impact of SO2 on Oryza sativa growth and photosynthetic contents was discovered by Singh L.P. (2002). Observed a marked decrease in total chlorophyll contents as well as chlorophyll a and b concentrations as a result of SO2's impacts on Zea mays seedling development. (Kumari & Jayabalan 2007). In their study, Singh and Javid (2003) found that when exposed to concentrations of 0.1 and 0.2 ppm SO2, the chlorophyll contents of Vigna mungo significantly decreased. When exposed to SO2, Muriefah and Al-Jwaizea (2004) discovered that it had an effect on in wheat and barley seedlings and discovered reduced levels of protein, chlorophyll, and carotene. The effects of sulphur dioxide on mustard and wheat plants were investigated by Joshi and Chauhan (2009). Ascorbic acid, carotenoids, total chlorophyll, chlorophyll-b, and wheat and mustard plants showed a considerable decline in these biochemical markers. The effects of air pollution on biological components of Eucalyptus camaldulensis were investigated by Seyyednejad and Koochak (2011). Plants at polluted sites showed increased solubility of two biochemical contents: protein and carbohydrates. When exposed to SO2, certain trees' photosynthetic pigments changed, according to Chauhan (2010). His research showed that both Ficus relegiosa and Mangifera indica have lower chlorophyll a and b levels in their leaves. In their study on the biochemical characteristics of spinach (palak), Irshad & Ahmad Fayz (2011) found that sulphur dioxide reduced the levels of photosynthetic pigments and amino acids. Studying how air pollution affects Cajanus cajan and documenting the results Meerabai and Ramana (2012) found a significant decline in the levels of chlorophyll, ascorbic acid, and relative water content. Research by Padhi and Dass (2013) examined the impact of different amounts of sulphur dioxide on Lycopersicon esculentum growth characteristics, and they discovered a notable shift in chlorophyll content. The 2014 study by Agabire and Akporhonor looked at affects the biochemical and physiological pigments of some plants caused by SO2. Total chlorophyll, ascorbic acid, and proline concentration were found to be lower. In their study on the effects of varying concentrations of sulphur dioxide on the growth and biochemical parameters of Vicia faba L., Sharma & Sharma (2014) found that sulphur dioxide had a negative connection with biomass, shoot growth, and chlorophyll content.

D.S. College Aligarh was the site of the probe in 2021 and 2022. A company in New Delhi called PUSA supplied the pea seeds. Polythene bags of precisely the right size were used for spreading these seeds. The plants were fumigated with varying concentrations of sulphur after they had germinated for 20 days parts per million, namely 0.1, 0.2, 0.4, and 0.6 ppm. Fumigation of the plants was done in a fumigation chamber that was constructed using aluminium sheets and coated with Perspex. Rao and LeBlanc Method (1966) were used to produce sulphur dioxide. Arnon method (1949) used for evaluation determine the amounts of chlorophyll a and b. One set served as a control, while the other four were subjected to varying concentrations of sulphur dioxide in order to ascertain their effects.

The amount of chlorophyll in the leaves decreased as the SO2 concentration increased. At the 60-day mark after fumigation, chlorophyll-a concentration reductions of up to 23.81% are considered. Plants' chlorophyll a level drops more precipitously as they mature. The chlorophyll content decreased with increasing SO₂ concentration. At the same age, the chlorophyll b concentration of a plant may drop as much as 6.16 percent, with a minimum drop of 4.01%. When exposed to SO2 at 0.7 ppm, plants have a maximum loss of 15.01% in chlorophyll b after 60 days of age. By the 60-day mark, total chlorophyll had dropped by 20.42 percent.

Sodium bicarbonate is a significant phytotoxicant and dangerous for plants. The biochemical parameter is most important for plant growth. Keeping this view in mind in present study was to evaluate the results of sulphur dioxide on biochemical parameters of Pisum sativum. They results found loss in chlorophyll a and chlorophyll b due to higher concentrations of sulphur dioxide.

Table -1 Changes in chlorophyll content as a function of sulphur dioxide concentration in Pisum sativum.