This experiment was conducted to assess how certain kinds of fertilizer affect plant growth. My partner and I focused specifically on using sugar as a fertilizer, to see how it would affect our bean plants. Our experiment consisted of a control group and an experimental group. Both plants had 10 mung beans as well as soil. The experimental group was given sugared water daily, while the control group was given tap water. Our hypothesis was that sugar would be detrimental to the plant, allowing it to stunt its growth, as well as limit it to grow fully. The hypothesis was not supported through our data and results. Possible explanations for our results are given in the discussion section.
Sugars are essential for many functions in live organisms. In plants, sugars provide a source of carbon that helps with sprouting and other growth functions (Paul & Van Dijck, 2011). The effects of sugar on a plant can be both positive or negative, however, and their metabolism must, therefore, be tightly regulated (Schluepmann, Pellny, Van Dijken, Smeekens, & Paul, 2003). The study of the use and regulation of sugar has important implications for the growth of plants, particularly for the production of crops (O’Hara, Paul, & Wingler, 2013).
The use of sugar as a fertilizer in plant growth can be both positive and negative to germination and plant growth. Sugar can either increase the length of stems by increasing their energy or can decrease the length of the plant as well (Blazquez, Green, Nilsson, Sussman, & Weigel, 1998). The study by Blazquez et al. (1998) was conducted to assess how the sugar sucrose affects the growth of the plant. The researchers found that the plant's growth was altered in length after sugar was added to the growth medium. The hypothesis in this study is therefore that the addition of sugared water will have a negative effect on the growth of Arabidopsis. This was tested by growing two plants, one of which was the control plant and the other of which was the experimental plant. The control plant was given only water, while the experimental plant was given water and sugar after it had a chance to grow during the first week with the control plant. The lengths of the stems of both plants were then measured to determine if there was a difference.
The experiment began with two pots of Arabidopsis thaliana shoots. One pot was designated the control plant while the other was designated the experimental plant. Plants were kept in a window side by side so that they received the same environmental conditions except for the water or sugar-water mixture. Over the first week of our experiment, we watered both plants equally ensuring the water quality was optimal. Both plants were given about a cup of tap water over 2-3 days, thus allowing them some time to grow before conducting our experiment with the sugared water.
During the second week of our experiment, the watering of the plants was done differently. One plant became our experimental group and was watered with one cup of sugared water every 2-3 days, while the other plant became our control group and was watered with the same cup of tap water every 2-3 days. The sugared water concentration was one teaspoon of sugar mixed and dissolved in one cup of tap water.
During the third week of our experiment, we continued to do the same routine as done in week 2. Around November 8, 2016, we had to return our plants to the lab. In this lab, we analyzed our plants, measured them, and wrote down our observations. The length of the stems of the plants was measured in centimeters, and data were recorded in the Microsoft Excel computer program. About our hypothesis, which we believed that sugar would stunt the growth of our plant, we conducted a t-test to see if we would accept our hypothesis and if there was a major significance in our results.
At the end of our third week in the experiment, the measurements in both our plants, the control and experimental group varied somewhat, as can be seen in Figure 1. The average value of the 5 stems pulled from the control plant was 13.34 cm, and the average value of the stems pulled from the experimental plant was 12.04 cm. After conducting the t-test, we found our p-value to be 0.331, which is not significant at the p < 0.05 level.
The hypothesis was not supported in this experiment, because the result of the t-test showed that there was not a significant difference in the growth of the two differently treated plants. Therefore, based on this study, we reject the hypothesis that the addition of sugar to the water will significantly negatively affect the plant’s growth. It is known that sugar affects plant growth in both negative and positive manners, and it is possible that the concentration of sugar in our experimental group was insufficient to affect the plant’s regulatory system (Schluepmann et al., 2003). It is also possible that the length of time that the sugar was added, or that the conditions of the light were not sufficient to alter the plant’s growth. Paul and van Dijck (2011) for example found that the plant’s growth was altered in conditions of darkened light as well as the addition of sugar. As well, there may not have been enough weeks elapsed to see the differences in growth of the plants – sugar may take more than a few weeks to affect the growth of a plant once it has already started as a shoot. Further experiments along these lines might, therefore, begin with plants as seeds, or be conducted over a longer number of weeks.
Blazquez, M. A., Green, R., Nilsson, O., Sussman, M. R., & Weigel, D. (1998). Gibberellins promote flowering of Arabidopsis by activating the LEAFY promoter. Plant Cell, 10, 791–800.
O’Hara, L. E., Paul, M. J., & Wingler, A. (2013). How do sugars regulate plant growth and development? new insight into the role of trehalose-6-phosphate. Molecular Plant, 6(2), 261–274.
Paul, M., & Van Dijck, P. (2011). How do sugars regulate plant growth? Frontiers in Plant Science, 2, 90. http://doi.org/10.3389/fpls.2011.00090
Schluepmann, H., Pellny, T., Van Dijken, A., Smeekens, S., & Paul, M. (2003). Trehalose 6-phosphate is indispensable for carbohydrate utilization and growth in Arabidopsis thaliana. Proceedings of the National Academy of Sciences, 100(11), 6849–6854.