High levels of salt concentration can have detrimental effects to the plants that are growing there. Rising salinity levels is one of the biggest attributes to the lack of growth within a plant population (Qados 2011). Salt concentrations in soils worldwide create problems each year and lead to loses of crop or even single plants (Garcia, Dattamundi, Chanda, Jayachandran 2019). Salt collects in soils that are artificially watered and once evaporation takes place there is a residue left behind (Breakthrough c.2019). The residue left behind is full of salts that continue to increase the levels of salinity (Breakthrough c.2019). Salinity causes extensive problems within plants not only the growth but also with biological issues (Garcia, Dattamundi, Chanda, Jayachandran 2019). The problems that salinity causes are plentiful, and they harm certain plant types more than others.
Bean plants are highly susceptible to damage that salinity causes as they can only withstand very small levels of salt (Garcia, Dattamundi, Chanda, Jayachandran 2019). Beans are one of the most reactive to rising salinity levels because of the way that they grow (Cook 2017). The long stems of the beans require water to act as a hydrostatic skeleton, adding salt to the water needed in the plant drives out the water causing the plant to dehydrate (Cook 2017). After the plant becomes dehydrated the effects are poor, and usually lead to death and loss of yield in crop (Cook 2017). Many new agricultural practices have been performed to lessen the bean plant’s sensitivity to salt in order to build a tolerance (Qados 2011). Creating a tolerance will help to create better bean plants for future use.
The experiment that was conducted looked at how different levels of salinity affected the growing of plants. There was prior knowledge that high salt concentrations had negative effects on the growing of a green bean plant but not directly about the effects that would take place. The salt levels were only slightly increased to make sure that there was not too much salt to completely overpower the growth of all of the plants. The purpose was to see if the salt would affect the growth according to inches of the green bean plants that were planted. The hypothesis of this experiment was that the three plants that were watered with the highest salinity level would show the least amount of growth out of all of the plants.
In this project, two packets of Harvester green beans were self-germinated. To germinate the seeds, a warm moist paper towel was placed on the bottom of a shallow Tupperware container. The beans were then taken out of the package and spread out on the first moist paper towel. Once all of the seeds were placed on the paper towel another warm, moist paper towel was laid on top of the seeds. The lid of the Tupperware was then placed on the container and placed in a warm space on the countertop. The seeds were checked daily, and the paper towel was rewet to ensure that the seeds were getting the warmth and moisture necessary to germinate. After four days of germination in the Tupperware container the seeds were opened up and sprouted and they were ready to be transferred to the soil.
There are nine cups involved in the experiment; three cups are used for each of the different levels of salinity used. Each of the 9 cups were filled ¾ of the way full of versatile indoor-outdoor planting soil. Then holes were made in all of the soil of each of the cups 1 ½ inches deep and two of the germinated Harvester bean seeds were placed and then covered.
The salinity solutions were then made for the dependent variables of the experiment. For the control group 0 tsp salt spring water was used to water the plants. For the first test group 1 tsp of salt was added to 500 mL of 0 tsp spring water and mixed well. For the second test group 1 ½ tsp of iodized salt was added to a bottle of 0 tsp spring water and mixed well. The plants were then all watered based off of their salinity level with ¼ cup of room temperature solution.
The plants were then placed in a moderately sunny area. After the planting and initial watering, the plants were checked daily. The plants were watered every 2 to 3 days based off of the level of water left in the soil. When the soil started to feel dry to the touch the plants were watered with 1/8 cup of solution. Every day the plants were checked for growth in the afternoon between 1-4 pm with an exception of a few days. After there were sprouts on the outside of the soil, I used a standard ruler and measured the growths by inches. I then took the reading of the height of the plant and marked it down in a notebook. The measurements were taken every day after the first time until the end of the experiment. The data was then put into Microsoft excel and made into a bar graph.
After examining the height, in inches, that the plants grew over eleven days there was a common trend that stayed almost constant between them. It shows the trend that the plants presented through their growth. The control group had (0 tsp salt), Group 1(1 tsp salt), and Group 2 (1 ½ tsp salt). While monitoring the growth, the plants that received high salt (1 ½ tsp) of Group 2 showed absolutely no growth and had no columns present on the graph. The Control groups 1-3 (0 tsp salt) had the most overall growth with the highest columns as well as the most abundant columns on the graph. Group 1 (1 tsp of salt) had mediocre growth as only Group 1-1 had plants grew showing one column on the graph. Group 1-1 had a drop around day 8 as the averages caused the height to decrease. Overall the Control group had 100% growth, with the tallest plant average being 12.09, Group 1 had 33% growth with the tallest plant average being 6.84, and group 2 had 0% growth.
Once all the data was collected the determination was that the hypothesis that the higher level of sodium, the less plant growth that will occur was accepted. The results were that the subgroups within the control all had the most successful growth, with the largest height and the most plants that sprouted. This was because they were watered with no sodium so the watered was soaked up into the roots and the plant did not go through any dehydration. Group 1 that received 1teaspoon of salt had slightly less growth. The height of the plants was a little lower, but only 2 out of the 6 plants sprouted. This was most likely caused by slight dehydration to the plants causing the stalk not to get too tall to where it could not create the hydrostatic skeleton that is needed to nourish the plant. Group 2 that was watered with 1 ½ teaspoon of salt showed absolutely no growth most likely related to severe dehydration. These results are slightly different than a similar experiment that was conducted: in that experiment the plants that were considered the control has lower growths than both of the mediocre salt concentrations, but the highest salinity matched with the lowest growth (Qados 2011). The results differed in another way too as all of the plants showed a height unlike this experiment that was conducted that showed absolutely no height in a lot of the groups (Qados 2011).
The results in this experiment could have been caused by a slight complication on the second day of planting. The cups were knocked over by a dog and cat and scattered among the floor. The seeds were picked up and replaced in the soil, but this could have affected the growing process causing so many of the plants not to grow at all. Another factor that could have messed with the data was that although all nine of the. Cups were placed in the same spot, some may have received more direct sunlight than others, helping with the growths of the front plants.
The data that was concluded from this experiment is very important to science. It could lead to many agricultural advancements to better understand how salinity affects the bean plant after a numerous amount of days (Qados. 2011). This data is also very important to science because it further provides data for not only just how salinity effects the bean plant, but instead how different levels cause different effects.
- Breakthrough: How Salt Stops Plant Growth. c2019. Washington DC: Carnegie Institution for Science; [accessed 2019 Nov 17]. https://carnegiescience.edu/news/breakthrough-how-salt-stops-plant-growth
- Chanda S, Dattamundi S, Garcia CL, Jayachandran K. 2019. Effect of Salinity Stress and Microbial Inoculations on Glomalin Production and Plant Growth Parameters of Snap Bean (Phaseolus vulgaris). Agronomy 2019, 9(9):545.
- Cook E. 2017 Sep 21. How Salt Tolerant Is a Bean Plant. Gardenguides.com. [2019 Nov 17]. https://www.gardenguides.com/131773-salt-tolerant-bean-plant.html
- Qados AA. 2011. Effect of salt stress on plant growth and metabolism of bean plant Vicia faba (L.). Journal of Saudi Society of Agricultural Sciences, 10(1):7-15.