Duisek Amanzhan crit B,C (seed growth)
RQ: To what extent the pH of the water (pH 3, 5, 7, 9 , 12) effects on the growth of a bean seeds?
Explanation of RQ: In general, plant growth is a complex process that is largely influenced by both environmental and chemical factors. In this investigation work I decided to use various values of pH of the water as the growing field for the bean seeds. I think that pH is a very essential chemical factor that can significantly affect on the growth of seeds due to its impact on the acidity of the growing conditions. The question is important, because agriculture has always played an important role in humanity, and an extensive and tested knowledge of factors that influence the success of plant growth certainly benefit and facilitate the progress of society and economy. The question will be answered by exploring the effect of pH on the height of bean seeds that will be germinated during a set time of 7 days. The value of height of the grown seeds will be the results of my experiment which are going to be tested and monitored. I am going to conduct 3 trials in 5 different samples of pH in order to get more accurate results.
Background: As stated by Education Science Tips (n.d.) the process of the growth of a seed into a small plant is called germination. These fundamental process has three main stages: Imbibition phase, latent phase and exponential growth phase. Based on the research, the pH could affect the germination at the very initial phase which is imbibition, because of the fact that pH of the surrounding effect on the enzyme’s’ activity. The water with pH 7 is the most efficient solution in order to activate the enzymes. This information is very important because it can significantly increase the efficiency of plants watering. Usually, people use rainwater as a source of watering for a long time in order to save money. However, nowadays due to the environmental problems, we do have acid rains which has high concentration of acid in water which can negatively influence on the plants. We know that acid rain has pH below 6. In my experiment I have such pH values (pH = 3 , pH = 5) and by conducting it, I can reveal and know exactly how does acid rain and acidic water influence on the plants growth. Moreover, the pH of the water also influences on the soil, thus effects on the soil prolificacy, ability of plants to absorb nutrients and efficiency of fertilizers. So this experiment will provide many useful answers in case of plant growing which could be practically implemented in order to increase the agricultural productivity.
Hypothesis: I assume to see the high growth at the pH=7. This expectation based on the background information where it is clearly seen that pH has important role at the imbibition phase and also on the enzyme activation. The research found that pure water is the most suitable watering for enzymes to work properly. A pH level that is too low may destroy the unstable structures of the young sprouts of the bean seeds during the process of germination, because the conditions will be too acidic and unsafe. Highly acid solutions may have a negative effect on the balance of such micronutrients as phosphorus or magnesium and also can cause inactivation of enzymes (Shoemaker & Carlson, 1990). So, the most efficient condition for bean seeds to grow was found in pure water.
Independent (including how these variables will be controlled)
pH of the water
I will pour different already prepared pH solutions (3, 5, 9, 12) and water into the 6 Petri dishes
Dependent (including how these variables will be controlled)
height of the bean
I will measure the height using ruler with uncertainty of 0.5 mm
Controlled (including how these variables will be controlled)
bean type, water amount, temperature
Bean type – red bean seeds only. Amount of water – 30 ml of the solution would be added using measuring cylinder with the uncertainty of 0.5 mm.
Temperature – room temperature 26 degrees.
Wear gloves and goggles
Be accurate with different pH solutions, use pipettes to grab them.
Measuring cylinder (uncertainty of 0.5 mm)
Petri dishes X 5
cotton pads X10
pipettes X 5
pH solutions 3, 5, 9, 12 (each 100 ml)
Pure water – 100 ml
Take measuring cylinder and measure 30 ml of solution with pH=3
Pour measured solution into the cotton pad
Take 3 seeds and separately from each other put them onto the the cotton pad
Accurately place the cotton pad with seeds into the petri dish
Cover the seeds with another cotton pad
Mark the petri dish with the title of pH – pH 3
Repeat all the steps from 1-6 with pH 5, 7, 9 and 12.
Processed data table
length of root / mm ±0.5mm
average length of root / mm ±0.5mm
Analysis and interpretation:
In the processed data table, I see that the results under the same pH value are not so far from each other, excluding the pH 5 solution. There are several reasons for such uncertainty, that is going to be discussed later. Still, there are 5 points of 5 different pH solutions on the graph. However, it doesn’t fit expected trend from my hypothesis. The graph demonstrates a downward trend in the relationship between the pH level and the length of bean roots, showing an indirect and negative linear correlation. As the pH increases, the length of the root decreases, and at the pH 9 and 12, the growth is the lowest ( 10 mm and 0 mm) . The best growth was revealed on the pH 3, which was not expected and the reasons for that will be mentioned below. There is also a big difference between the pH value at 5 and 7 (30 mm). The differences were also mentioned between the results of certain pH. For instance, pH 5 shew 70, 30 and 20 mm, which is actually big difference. Thus, it is evident that there are some outliers, specifically on the values of 7 and 9 in the levels of pH, if a linear fit is applied. These occurrences may be the result of flaws and limitations in the method that made the trend less consistent and stable.
Evaluation of Hypothesis
Eventually, the results of the experiment didn’t prove my hypothesis:
“I assume to see the high growth at the pH=7. This expectation based on the background information where it is clearly seen that pH has important role at the imbibition phase and also on the enzyme activation. The research found that pure water is the most suitable watering for enzymes to work properly. A pH level that is too low may destroy the unstable structures of the young sprouts of the bean seeds during the process of germination, because the conditions will be too acidic and unsafe. Highly acid solutions may have a negative effect on the balance of such micronutrients as phosphorus or magnesium and also can cause inactivation of enzymes (Shoemaker & Carlson, 1990). So, the most efficient condition for bean seeds to grow was found in pure water. ”
From the data results, I can see that the largest root was grown at the pH 5, which is 50 mm ±0.5mm. While, at the pure water- pH7, the maximum height is only 11 mm ±0.5mm only and the average is 10 mm ±0.5mm. That was totally unexpected result, because solution with pH 7 had to give better effect on growth and pH 3 no growth at all. As my control variables were weakly controlled, my hypothesis wasn’t confirmed. These results could also be explained not only by weakly controlled conditions, but also by the scientific reasoning explained in the background information. Given that the largest growth was achieved at the pH 3, it is reasonable to assume that low acidic concentrations may be beneficial for some plants, boosting the length of the roots. A connection with real life can be made, because the majority of agricultural entities apply fertilizers with acids to increase the output.
However, I still think that pure water is the most efficient environment for seeds as my hypothesis was based on scientific reasoning and strong background theory as well. The results of the experiment didn’t fit the actual hypothesis and claim that the best growth is under the pH5. Nevertheless, the hypothesis was partially correct, as the growth of bean seeds was not successful under extremely high pH conditions that are higher than 7, such as 9 or 12, as I stated in the hypothesis that 7 is the most effective pH value.
Evaluation of method
Considering the efficiency of method, I think that it was relevant and properly written, where variables could be manipulated. However, there were several weaknesses which decrease the preciseness of results. First, because of weekends and holidays, I didn’t water my seeds regularly. Moreover, I always used different volume of solutions in every watering. Also, I wasn’t sure about the accuracy of prepared pH solutions because I didn’t prepare them by myself due to the lack of time in experiment conducting. There is also a big probability of losing exact value of pH in solutions during the time because they were also used by the another students with their own pipets . These all reasons arouse uncertainties onto the final results because of different conditions and cause several difficulties for seeds growing. Because of difficulties in the performance part of method, the results weren’t so precise as they could be.
Generally, the idea and principles of method are valid. The problems were in the performance part which need few improvements. First, I suggest to organise a schedule of watering which should be strictly followed. The improvement of creating a schedule would enable consistency and reliability in results, as the amount of water and moisture will be controlled constantly and systematically. This improvement will certainly improve the outcomes of the experiment, because random errors will be minimized, and all samples would receive equal conditions.
Second, the pH solutions should be prepared and used only by myself. It would be more reliable to control the acidic levels independently. This improvement could be achieved by using one type of concentration of acid and then adjusting the pH level by mixing the acid with water to create concentrations of 50% or 75%, for example. Afterwards, the pH value of each concentration could be measured with the SPARK device for a more detailed and effective evaluation of the effect of a specific pH value range on the seed germination. Thirdly, each pH solution need to have its own pipettes in order to avoid mixing with other solutions. This improvement is vital in adjusting the method and reducing flaws, given that an undesired mixture of different solutions would result in invalid data, which will affect the reliability of gathered results. Fourthly, to use the exact, constant amount of the solution on watering which will be measured with measuring cylinder. Using a measuring cylinder is essential, because the experiment would not be “fair”, if the aspect of controlled variables, which include the amount of solution being used for watering, is not constant. All these mentioned improvements are given in order to decrease the uncertainties of the experiment and both random and systematic errors, making the results more precise; however, the experiment by itself is acceptable and valid, because the research question was answered. Even though the hypothesis was not verified, the effect of the pH of water on bean seed germination was identified and analyzed.
Germination of seeds and the 3 stages involved, (n.d.). Education science tips. Retrieved from http://www.rajaha.com/germination-seeds/
Lovejoy, R. (2017, November 21). How Does pH Affect Plants? Retrieved May 7, 2018, from http://homeguides.sfgate.com/ph-affect-plants-49986.html
Nitric Acid. (n.d.). Retrieved May 7, 2018, from http://www.casaleproject.cz/en/products/nitric-acid
Shoemaker, A., & Carlson, W. (1990). PH Affects Seed Germination of Eight Bedding Plant Species. Retrieved May 7, 2018, from http://hortsci.ashspublications.org/content/25/7/762.full.pdf