Carbon dioxide in the atmosphere
Rain water is slightly acidic in nature. The pH of the rain water ranges between 5.6 to 7.0 due to the fact that carbon dioxide in the atmosphere get mixed with the water as it falls down. The human interventions like burning of fossil fuels and industrial process increase the quantity of acid in the rain water (McColl & Jhonson, 1983). Due to the above factor the acid rain has become a crucial environmental factor. The problem of acid rain was limited to some European and North American countries by the 1970's but to rapid increase in urbanization and industrialization in other parts of the world has raised the concerns in other parts of the world. The countries like China, Pakistan and Malaysia are among the highest receivers of the acid rains (McColl & Jhonson, 1983).
The effect of acid rains on the crop growth and output has been studied for a while now. The studies started almost 20 years ago. The study of adverse effects was conducted using both glasshouse and field experiments. Acid rain is simulated and its effects on the plant growth are measured. The most common effect on the plant growth is injury to the foliage. The reduction in seeding growth and emergence is also noted in some of the experiments. To reduce the adverse effects of acid rain on the plant growth continuous experimentation is required to formulate protection measures for the plants.
Germination and plant growth
To study the adverse effects of the acid rain present experiments were conducted. The variables under study were seed germination and plant growth. The plant selected for the study was rice plant as it one of the most cultivated crop in the world especially in Asia. The type of rice plant selected for the experimentation is known as MR84 (Johnson et.al, 1983). It is the most frequently cultivated plant in the world. The assumption was to study the adverse effects of the acid rain on the plant growth and seed germination. It is believed that the acid rain negatively impacts the both selected variables.
In a dry sagebush steppe in Oregon (USA), 4 medicines or circulations (control, regular conveyance, winter and spring appropriation) were thought about (Johnson et al, 1983). The winter treatment got 80% of its water amongst October and March; in the spring treatment 80% of water was connected amongst April and July; and the common appropriation treatment got a precipitation coordinating the site's long haul (50 years) conveyance design. At long last, a control outside the safe houses got normally happening precipitation. The primary critical changes in the surviving plant group happened 4 years after the start of the trial, when profitability was most noteworthy in the spring treatment, which concentrated 80% of the mean yearly precipitation in that season (Johnson et al, 1983). The deferred reaction confirms the solid strength of this parched framework to changes in precipitation (Johnson et al, 1983).
Six rainout asylums were built up in a semi-parched field in the Santa Rita Experimental Range (Arizona, USA) on two unique soils; three on sandy-topsoil and three on clayish soils Yu et al. (2002). A few reactions were tended to in this framework. Yu et al. (2002) examined the impact of soil sort and grass species on soil dampness; Yu et al. (2002) measured net environment trade (NEE) of CO2 and evapotranspiration (ET); Yu et al. (2002) examined the progression of leaf photosynthesis and water status in local and non-local grass species, and Resco et al. (2009) examined obliges to leaf gas trade after precipitation beats.
Simulated Rain Water Solution
The above table shows the components present in an acid rain. A stock solution was prepared according to the compositions present in the table. The stock solution contained a mixture of several chemicals prepared in the one liter solution. The acid rain solution was then adjusted to the desire pH levels by using sulphuric acid. The pH values selected for the experiment were 3.5. 4.0, 4.5, 5.0 and 5.6.
Experiment 1: Effects on the Seed Germination
Rice seed were sown in the depth of about 1 cm and 3 cm apart in a plastic tray. Three trays were selected replication of each other to test the effect of various pH values on the rice seeds containing 100 seeds. The pH solutions were sprayed on the trays manually to keep it in the wet condition. The seed germination was noted every two weeks. This variable was noted when the plants appeared above the surface of the soil.
Experiment 2: Effect on the Plant Growth
Rice seedlings were studied in the plastic tray for 21 days. The pots in which these plants were studied were filled to about 5.6 cm to the top. The plants were managed according to reliable agricultural methods for rice cultivation. The acid rain was applied to the plants using a specified rain simulator. The rain simulator system included a water pump, polypipes, nozzles, and a controller. The rain was dispersed almost 1m above the plants. The rain was applied for almost 20 mins. The quantity of rain was estimated according to the average rain fall received by the rice plants in a real time scenario.
The data obtained from both experiments was efficiently randomized. The obtained data was observed for variance, and the treatment of plants was compared using S.D test
Independent Variables: Seed growth, plant growth, effect of pH on the plants.
Dependent Variables: Temperature, amount of water absorbed by the plants, height of the plants at different pH levels.
Human activities and Effect on Seed Germination
Human activities have affected this planet in an adverse manner. Today air and water pollution have their impacts on the fundamental ecology of the planet earth. It is a challenge for the environmental professionals to highlight the problems and their solutions to make this world a better place for human beings and future generations. Acid rain is a problem which is directly or indirectly caused by the human activities. The use of industries and automobiles is not only affecting the ozone layer in a negative manner but also having adverse affects on the growth of plants and agriculture output of different countries. The reason for the selection of this experiment is to study the impact of the acid rains of seed life and plant growth.
Most of the seed germination happed on the 7th day and 10th day of sowing. With the decrease of pH level the germination of seeds also decreased. This decreased in the level was ranged between 89% and 94%. It was minimum for the pH 3.5 as it decreased the rate by 3% to 5%. No significant difference was noted for germination between pH 4.0 and 4.5. However, a note able difference was noted for pH 5.0. Some sort of germination was shown at each pH level.
Data gathered from the experiments showed that the acid rain had no significant negative effect on the plant growth and height. However, it was noted that the height was a bit taller in case of lower pH. The results are summarized in the following figures:
Figure: Effects of Acid Rain on Plant Growth (Johnson et.al, 1983).
As shown from the above diagram number of tillers for the pH 5.6 was greater than number produced for the treatment on Ph 3.5. This number was significantly decreased at the time of the harvest. From 45th day to 75th day this rate of decrease was noted to be faster. The number of leafs at each plant was also not affected by the acid rain treatment of the rice plants. Maximum number of leafs were attained at 75th day (Johnson et.al, 1983). Number leafs ranged from 99 to 108 per plant. As the plants reached maturity the number of leafs decrease due to the natural process. The difference in the number of leafs was also due to difference in tiller number.
From the results of the experiment it is clear that the variables like seed germination, tiller number and number of leafs were negatively affected by application of simulated acid rain. On the other hand, the height of plants showed no significant difference on the application of acid rain. The heights remain same at each level of experimented pH. Earlier studies conducted on the rice plants observed that the plant showed variable growth rates on the application of the acid rain. These positive and negative effects on the plants on the application of simulated acid rain might be due to the fact the sulphate component in such rains is higher as compared to natural rain (Johnson et.al, 1983).
In present experimental study nor injury was observed on the plants due to the acid rains which increased its validity. However, one might argue that the reduced leaf numbers are due to some sort of injury. In the rice plants, there is no visible injury to the plants on the applications of the acid rains but there is also evidence suggesting that plant suffer from injuries on the application of dry SO2. Moreover, the affects of the acid rain also dependent on the acidity of the natural rain. The results of the present experiments are also supported by several authors including Yu et.al (2002) and Singh and Agrwarl (2004). The results of this study like earlier show that acid rain having pH 3.5 can significantly affect the growth of rice plants (Johnson et.al, 1983).
As stated in the previous section, the experiments were performed by different researchers on different plants. The experiment conducted in this report can be repeated by anyone to study the results and variables selected for the study. The experiments were conducted on using the same parameters for wheat plant earlier. Rice plants were selected for this study as they are the second most cultivated crop in the world after wheat.
McColl,T J.T G., & Johnson,T R. (1983). Effects of simulated acid rain on germination and early growth of Douglas-fir and ponderosa pine.T Plant and Soil,T 74(1), 125-129. doi:10.1007/bf02178747
Qiu,T D., Liu,T X., & Yu,T S. (2002). EFFECTS OF SIMULATED ACID RAIN ON LONGAN PHOTOSYNTHESIS.T Acta Horticulturae, (558), 301-304. doi:10.17660/actahortic.2001.558.49
Singh,T B., & Agrawal,T M. (2004). Impact of Simulated Acid Rain on Growth and Yield of Two Cultivars of Wheat.T Water, Air, & Soil Pollution,T 152(1-4), 71-80. doi:10.1023/b:wate.0000015331.02874.d
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