Soil salinity affects the germination of agricultural plants such as beans and corn as salts accumulated in the soil affect the plants’ osmotic properties hence excessive accumulation of salts on agricultural farmlands may reduce water uptake in plants. Different plants have varying levels of tolerance to salts hence a certain level of salt accumulation might completely discourage the growth of some plants (Assouline et al 2015). The major impact of salts on agricultural soil is the reduction of water availability in the soil, which is essential for plant photosynthesis. The purpose of this experiment is to determine how different salt concentrations affect the germination of bean seeds by growing the same number of healthy bean seeds in different salinity concentrations while keeping other germinat0oion factors such as moisture and warmth uniform (Machado &Serralheiro 2017). The main question that the experiment intends to answer is, does the level of salt concentration affect the germination of healthy bean seeds? To what extent of salty conditions can germinating bean seeds tolerate? The hypothesis statement that guided the experiment was bean seeds sown petri dish containing 2% saline solution will show less vigorous to no germination at all as compared to those sown in Petri dishes containing 1.5%, 1%, 0.5%, and 0.0% saline solution. Also, there is a high number of germinated seeds in the petri dish containing 0.0% saline solution as compared to other Petri dishes.
| Salinity of Solution | 0.0% | 0.5% | 1% | 1.5% | 2% |
| # Germinated Day 1 and Observations | The bean seeds retained their whitish color. There was no germination yet. There was no change in size. There was no significant change in weight upon weighing. | The bean seeds retained their whitish color. There was no germination yet. There was no change in size. There was no significant change in weight upon weighing | The bean seeds retained their whitish color. There was no germination yet. There was no change in size. There was no significant change in weight upon weighing | The bean seeds retained their whitish color. There was no germination yet. There was no change in size. There was no significant change in weight upon weighing | The bean seeds retained their whitish color. There was no germination yet. There was no change in size. There was no significant change in weight upon weighing |
| # Germinated Day 2 and Observations | No seed germination. The seeds start increasing in size and the color of the beans begin to change from whitish to grey. | No seed germination yet. Seeds start increasing in size although the increase was smaller than in the previous petri dish. The seeds take up a brown-greyish color. | No seed germination yet. There was little seed imbibition. The change in mass was smaller than in the previous petri dish. The color changed from white to brown. | No seed germination yet. There was minimal increase in size and increase in mass was lesser compared to the previous petri dish. There was color change from whitish to brown. | No seed germination yet. There was negligible increase in both size and weight of the seeds in this petri dish. There was color change from white to brownish. |
| # Germinated Day 3 and Observations | 5 out of 10 seeds had sprouted while most of the rest were swollen. The color of the seed coat was grayish and there was a considerable increase in mass. | 4 out of the 10 seeds showed signs of sprouting while the rest showed imbibition. The weight difference was lesser than in the first petri dish. There was no significant color change. | 3 out of the 10 seeds showed signs of sprouting and the rest were swollen. There was no significant color change. Mass before and after germination varied slightly. | 2 seeds had germinated. No significant color change. Change in mass was negligible. The seeds had increased slightly in size. |
1 seed had germinated while the rest were still in the imbibition stage. The change in mass was negligible. There was a slight increase in size of the seeds due to swelling |
| # Germinated Day 4 and Observations | 7 seeds were fully germinated with shoots and radical while 3 were sprouting. There was a considerable increase in mass. The seeds had increased in size too. The color of germinated seedlings was green while the rest were greyish. | 5 seeds were germinated. There was an increase in mass in day 4 as compared to day 1. There was also increase in size of seeds. | 4 seeds had germinated while the rest remained swollen. There was slight increase in mass and size. There was no notable change in color of the seed coat. | 3 seed had germinated, 4 swollen while the rest showed no change. There was a slight increase in weight and size, though lesser than that in dish 3. There was no notable change in color. | 2 seeds had germinated. 6 seeds were swollen. There was a negligible change in size, weight, and color. |
| # Germinated Day 5 and Observations | 10 seeds were germinated. There was a significant increase in both mass and size of the seedlings. The color of the seedlings was mostly green. | 7 seeds were germinated and there was a considerable change in mass, size and color. | 6 seeds responded to germination while the rest were in the imbibition stage. There was a slight change in mass, size and color. The seed coats had changed from whitish to grey. | Only 4 seeds germinated. There was little change in mass and size as well as color. | 3 seed germinated. There was a negligible change in mass, color and size. |
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| Days | Salinity of the solution in % | ||||
| 0.0 | 0.5 | 1.0 | 1.5 | 2.0 | |
| Day 1 | 0 | 0 | 0 | 0 | 0 |
| Day 2 | 0 | 0 | 0 | 0 | 0 |
| Day 3 | 5 | 4 | 3 | 2 | 1 |
| Day 4 | 7 | 5 | 4 | 3 | 2 |
|
Day 5 |
10 |
7 |
6 |
4 |
3 |
Farmlands become salinized mainly due to continuous irrigation, especially in hot and arid areas due to rapid evaporation that leaves salts accumulated in the soil. Another reason for salinization in most farmlands is the removal of deep-rooted vegetation that covers the topsoil and shields the soil from excessive evaporation that leads to the accumulation of salts (Zhou et al 2017). Another cause for salinization is the salting of icy roads and the application of fertilizers which get leeched through the soil layers with time increasing the salts concentration. List three ways to slow or prevent the salinization of soils. Frequent monitoring of underground water and creating a balance between salts in water and adjacent land. Establishing more deep-rooted native vegetation to shield soil water from evaporation. Embracing drip irrigation rather than canal irrigation reduces the amount of water that is lost through evaporation otherwise reducing the rate at which salts are accumulated in the soils. This serves as a control experiment with no treatment to show the expected results if the seeds were not subjected to the high-concentration treatment.
Conclusion
From the experiment, the hypotheses stated earlier in the report are correct since the rate of germination in the petri dish with 2.0% concentration exhibited less rapid germination as compared to those seeds in the petri dish containing 0.0% salt concentration. This is because the excessive salt concentration in the last petri dish acted as a germination inhibitor hence affecting the osmotic properties of the germinating seeds. This reduced water uptake, which is a vital component in the germination of a seed. From the experimental data, only 3 seeds in the last petri dish containing 2.0% salt solution germinated, while the rest did not. Also, due to the minimal uptake of water and other growth nutrients, there was a negligible change in the size and mass of the seeds, measured over the growth period of four days. From the above lab session, it is evident that high levels of salt concentration in the soil reduce the growth rate of plants due to the inability of plant cells to uptake water and mineral salts due to the high osmotic gradient created by this high concentration. The levels of salinity should be frequently monitored to ensure a balance between the plants’ cell sap and the surrounding soil water. More efficient irrigation systems like the use of drip systems instead of the traditional canal systems can help minimize the amount of water that evaporates. This experiment is an illustrative model of how saline farmlands reduce crop yields by impeding plant germination.
References
Assouline, S., Russo, D., Silber, A., &Or, D. (2015). Balancing water scarcity and quality for sustainable irrigated agriculture. Water Resources Research, 51(5), 3419-3436.
Machado, R. M. A., &Serralheiro, R. P. (2017). Soil salinity: effect on vegetable crop growth. Management practices to prevent and mitigate soil salinization. Horticulturae, 3(2), 30.
Zhou, M., Butterbach‐Bahl, K., Vereecken, H., &Brüggemann, N. (2017). A meta‐analysis of soil salinization effects on nitrogen pools, cycles and fluxes in coastal ecosystems. Global change biology, 23(3), 1338-1352.
