Do different pH solutions affect the germination rate of mung beans, Vigna radiata?
The early growth of a seed is called germination. However, some seeds undergo what to be called a dormant period when it didn’t germinate even if the conditions are favourable to them. There are many factors affecting seed germination. These factors include water, oxygen, suitable temperature, light, pH and so on. If these are not optimal for a plant, then its ability to grow can be reduced. They can also be affected by abiotic factors such as pollution.
All seeds need water for germination. It is to hydrate them and supply a medium needed for active metabolism. There is a hormone present in some types of seeds which inhibits germination and therefore water is needed to wash it out of the since in order to germinate ?¹?. Moreover, the metabolic rate of a dormant seed is close to zero, but during germination, food materials are metabolised and synthesis of new materials takes place, thus water becomes a reactant in these chemical pathways ?²?.
Apart from these requirement, the process of germination and growth needs energy. The breakdown of organic molecules through aerobic cell respiration provides the ATP needed for the germination and growth processes ?³?. Therefore, a supply of oxygen is also another factor. Each plant species usually has an optimal temperature at which most of its seeds germinate.
Last, but most importantly, pH is also known to affect seed germination. pH refers to the ability of the solution to be more on the acidic side or more on the basic side of a pH scale. Pure water, as it is, is neutral, which has a pH level of 7. If solution is too acidic, it may damage the delicate structures of the seeds as they germinate, whereas if its too basic, it would expose the young plant to diseases that could be detrimental to their germination as a developing plant ???.
The soil’s pH is usually rated on a scale of 3.5 to 9.0 before putting the seeds, and most plants are found to do best in soil that tests within 6.0 to 7.0 – the neutral range. If the soil is tests to be higher or lower than this neutral range, growth may still occur but the improper balance of nutrients may exhibit through poor growth and development of the seeds ???. Thus, pH level in soil becomes a really important factor to be considered in the success rate of seeds in the germination process. Therefore, I conduct this particular experiment to observe the effect of pH on the germination rate of seeds by using mung beans, Vigna radiata.
?¹? “Damon, A., McGonegal, R., Tosto, P., & Ward, W. (2014). Pearson Baccalaureate Biology HL. Spain: Pearson Education Limited.”
?²? “Rashid, Kamaludin, et al. Comprehensive College Biology. SAP Publications SDN. BHD, 2016.”
?³? “Allott, A. (2001). Biology: IB Study Guides (Third ed., Ser. 2014). Oxford, England: Oxford University Press.”
???eNotes, 14 May 2012, https://www.enotes.com/homework-help/how-do-different-ph-levels-affect-germination-337812. Accessed 28 Feb. 2018.
??? “How Does pH Affect Plants?” Home Guides | SF Gate, homeguides.sfgate.com/ph-affect-plants-49986.html.
In this experiment, it is predicted that if the level of pH is too low it could hinder the growth of mung beans, similarly if the pH level is too high could also hinder the germination and growth of mung beans. It is because the difference in pH level affect the germination and growth of bean sprout.
(Independent, dependent, control variable) Likely impact upon investigation How the variable will be changed, measured or controlled?
– pH value of solutions By changing this variable, the dependent variable could be compared in order to see the differences in rate of reaction of pepsin enzyme that showed the efficiency of enzyme activity depending on the Ph value of the solutions containing 0.1 M of hydrochloric acid, distilled water, or a mixture of both. Different volume of 0.1 M hydrochloric acid and distilled water in each boiling tube were chosen which is a 20 ml of hydrochloric acid, 20 ml of distilled water, 15 ml of hydrochloric acid and 5 ml of distilled water, 10 ml of hydrochloric acid and 10 ml of distilled water, 5 ml of hydrochloric acid and 15 ml of distilled water. These differences in volume would produce different pH and have effect on the hydrolysis of albumen.
– Time taken for each pH group of mung beans to germinate This is a good measure to answer the research question because the independent variable would make differences in the time taken to hydrolyse albumen by calculating the time taken for biuret solution to change colour.
The measurements would be taken by calculating every 5 minute interval of the grooves that filled with violet coloured biuret solution in order to find the time taken for pepsin enzyme to hydrolyse albumen.
– Volume of different pH level solutions
– Temperature of surrounding
– Number of mung beans on each pH level group
– Amount of sunlight exposed
These variables might impact the data collected as the experiment would be repeated several times to make comparison between the pH and time taken to hydrolyse albumen. The volume of 0.5% pepsin solution and albumen would be kept constant which is 5 ml and 3 ml for each boiling tube. The time interval to observe the colour change of biuret solution must be 5 minutes using a stopwatch.
Table 1 – shows the independent, dependent, controlled and uncontrolled variables for the experiment, the likely impact of it on the experiment and the ways to control and measure it.
Paper towels 6
Paper plates 3
Table 2 – shows the apparatus needed in the experiment.
Mung beans 30
Distilled water 20ml
Diluted vinegar 10ml
Baking soda 2.0g
Table 3 – shows the materials used in this experiment
1. Put out three paper plates which are to place the mung beans on.
2. Next, dissolve 2g of baking soda in 10ml of distilled water to make a baking soda solution that represent an alkaline solution.
3. After that, dip two paper towel in each solution which are distilled water, diluted vinegar, and baking soda solution until it is completely wet.
4. Then place one wet paper towels of different pH, folded on each plate. Distilled water represents the control of the experiment.
5. Next, arrange ten mung beans on each paper towels and cover them with another paper towel which had been dipped in the same solutions.
6. Place the plates beside the window to ensure the beans get the constant sunlight and are under the same room temperature which is 25°C.
7. For every day in a week, observed the mung beans on each plate and record the observations.
8. When the beans are starting to sprout root and leaves, the top paper towel is to be remove.
9. The number of beans germinated and the time it takes for each mung beans following the different pH level of solutions they germinate on while maintaining other factors are recorded in a table.