Final Seed Germination Lab Report

1 The Effects of Four Salt Solutions on Buckwheat Seed Germination Abstract Diffusion involves the movement of particles from an area of high to an area of low concentration, and the type of diffusion relevant to the current experiment is osmosis. Osmosis is similar to diffusion but only regulates the movement of water, which in this case is inhibited by salt solutions. The purpose of the current experiment was to observe the effects of various salt concentrations on buckwheat seed germination. This was done by placing the seeds in a moist, sealed bag in a dark environment for a period of six days with daily observation. Afterward, the seeds were removed and both measured for radicle length as well as mass. The results revealed that out of KCl, NaCl, CaCl, and MgCl, KCl slowed germination the most. The lengths and masses were also the least in comparison with the seeds affected by the other salts. From these results, it can be concluded that not only does KCl have the most effect, but salinity inhibits seed germination. Introduction The germination of seeds depends on the diffusion of salts and the osmosis of water. It involves the growth of seeds as a form of reproduction. Seeds are essential to human life as they are needed for food. However, due to environmental conditions, the salinity of Earth’s soils is increasing, inhibiting the germination of seeds. In order to control the effects of salinity on seeds, today’s researchers are testing ways to improve salt tolerance in plants. Testing is done by observing the effects of different salts and salt concentrations on certain crops that are commonly used by humans such as quinoa. An example of a study conducted on various salts and their effect on plants is Panuccio’s experiment. (Panuccio et al., 2014) If research continues, it will significantly benefit the growth of plants, even with increasing global warming. Healthier plants would then improve the chances of life in the future since they are needed for life. 2 Generally, diffusion is the movement of particles such as solids and gases from a higher to lower concentration in any direction (Naqvi, 1974). Osmosis is a type of diffusion involving the movement of water at the cellular level. It is affected by the concentration gradient, moving from an area of high to low water concentration. This is the same for the flow of water from low to high solute concentration because water has a general tendency to flow where there is less water. Osmotic pressure competes with osmosis by interrupting the flow of water by forcing it to reach equilibrium and relates to the force of gravity since the pressure caused by gravity affects osmosis. (Ray, 1960) Both diffusion and osmosis can be associated with the process of seed germination for the reason that it involves the movement of water as well as a solution containing salt. The solution surrounding the seeds is absorbed, causing the seeds to either germinate or fail to do so due to the particular type of solution. Similarly, a study conducted by Panuccio in 2014 experimented the impact of various salt concentrations on halophytes, which are plants that can withstand salinity and quinoa as they are one of the most protein-rich crops grown for food. In the experiment, the researchers used petri dishes and pots to place the seeds and soaked them in 25%, 50%, 75%, and 100% molarity concentrations of KCl, NaCl, MgCl2, CaCl2, as well as diH2O. They hoped to find the effect of the salt concentrations on halophyte and quinoa seed germination by observing seed growth. Afterward, it was concluded that the seeds saturated in the lowest concentration germinated further than those at higher concentrations while the seeds in water germinated fully. Specifically, the tonicity or the possible impact of concentrated solutions on the seeds was tested to determine whether the effects were hypertonic (high solute and less water) or hypotonic (low solute and high water), revealing that the seeds were hypertonic as the concentration of salt dominated the concentration of water in the solution. 3 The methods of Panuccio’s study are comparable to the current experiment because seed germination in both studies was tested through observation of the effect of the salt solution on the seeds. Particularly, the importance of Buckwheat seeds was that it allowed for a rapid germination rate as observed in the experiment. It is also relevant to modern day crops since Buckwheat is used to make various breads, pastas, and other carbohydrate-rich foods as a healthier alternative to regular wheat (Skrabanja et al., 2001). Salt solutions are crucial on the seeds’ salinity tolerance since the diffusion of salts as well as the osmotic pressure within the seeds is dependent on the concentration. Salt causes germination failure in crops, which is why research is being done to find ways in which seed germination is optimized even in saline soils. According to the research discussed on seed germination, it is vital to ensure that seed growth is possible even in harsh conditions because the world is dependent on high yield crops as a source of food. As discussed in Panuccio’s article, global warming has caused an increase in soil salinity, causing many seeds to die and fail to germinate properly. The objective of the current study was to test the effect of various salt solutions on the germination of seeds by soaking Buckwheat seeds in various salt solutions over a six-day time period. It was predicted that by observing the effects of 0.2 M concentrations of CaCl, MgCl, KCl, and NaCl on the seed germination of Buckwheat seeds, KCl would inhibit germination the most. Methods and Materials Two dry paper towels were folded in half. Ten seeds of Fagopyrum esculentum (buckwheat) were carefully placed in each towel and spread to create spaces between the seeds. The towels were placed in separate Ziploc bags. The first bag was labeled as the “control”, while the other was labeled with “0.2 M concentration of NaCl”. The 4mL pipette was then used to drip 4mL of distilled water onto the paper towel in the “control” Ziploc bag. After the bag was 4 sealed, another 4mL pipette was used to drip 4mL of 0.2 M concentration of NaCl onto the paper towel in the other Ziploc bag, then sealed. Both sealed bags were placed in a dark area at an approximate temperature of 70° F. They were observed at exactly 9:00 p.m. EDT every day for a period of six days. Each day, data was collected on the date checked, the number of seeds germinated, the temperature as well as light, and observations. Following this germination period, the seeds were taken out of the bags and their growth was measured and documented in centimeters using a standard ruler. The seeds were separately weighed on a mass scale and the masses were recorded. Results In Figure 1, the number of seeds germinated over the six-day germination period is compared with the use of various salts. According to the graph, KCl had the most negative effect on seed germination while the diH2O (deionized water) allowed the most rapid seed germination. Specifically, the average number of germinated seeds for KCl amounted to about seven while all seeds germinated in the deionized water. 5 # of Seeds Germinated Seed Germination 12.00 10.00 8.00 6.00 4.00 2.00 0.00 Day 1 Day 2 0.2M CaCl 0.2M NaCl Day 3 # of Days 0.2M KCl diH20 Day4 Day 5 Day 6 0.2M MgCl Figure 1 Effect of various salt solutions and deionized water on number of seeds germination over time period of six days Table 2 exhibits the average lengths of the radicles formed following the germination process. According to the table, the radicle length of the seeds germinated in deionized water was longest (4.57 cm) while the average CaCl2 radicle length was the smallest (0.393 cm). However, KCl had the most negative effect on the number of seeds germinated on average, it had one of the largest average radicle lengths. This shows that even though not many of the seeds soaked in KCl solution germinated, the seeds that germinated grew to long lengths in comparison with the other tested salts. Table 1 Average length of radicle per salt solution and water following seed germination period of six days. Salt Solution (0.2 M) Average Radicle Length (cm) NaCl 0.394 CaCl 0.3925 6 MgCl 0.74 KCl 0.426 diH2O 4.57 As for Table 2, the masses of the germinated seeds were measured and averaged to reveal that the seeds germinated in diH2O weighed the most (1.05 g). The seeds grown in the salts were much lighter, which tells the reader that the salt hindered absorption. Table 2 Average mass of seeds per salt solution and water following seed germination period of six days. Salt Solution (0.2 M) Average Seed Mass (g) NaCl 0.504 CaCl 0.43 MgCl 0.54 KCl 0.428 diH2O 1.0505 Discussion According to the results of the experiment, out of KCl, NaCl, MgCl, and CaCl, KCl had the most negative effect on the germination of the buckwheat seeds. This supports the hypothesis since it was predicted that the KCl salt solution would result in the least number of germinated seeds as compared with the other salts. It also resulted in the shortest radicle lengths as well as the lightest seed mass. The reason why KCl hindered seed germination is that the effects of salts 7 on seed growth are shared. Since seeds normally intake water through osmosis and use it to increase growth, adding a salt solution results in shrinking cells within the seeds. Since a concentration gradient is formed when osmosis occurs, water flow is dependent on areas of high versus low water concentration. It typically travels where water is not as abundant. In this case, the salt solutions interrupted osmosis in the seeds, causing most of the water to flow out of the seeds and causing it to shrink. This is when the seeds lose water, causing germination failure. This is also supported in the study conducted by researchers on the effects of salt solutions on popular crops such as quinoa in Panuccio’s study. In the experiment, various concentrations of salts such as CaCl were used to soak the seeds of these crops. Results showed that as the concentration increased, the number of germinated crops decreased due to the loss of water. (Panuccio et al., 2014) Another similar experiment was done by Bojović and others in which various NaCl concentrations were tested on Brassicaceae and Solanaceae seeds to observe salt tolerance (2010). It was found that the seeds tested with the lowest NaCl concentration germinated while the others failed to germinate. One more experiment was conducted by Camlica and Yaldiz where salt concentrations ranging from 0 to 240 mM were tested on basil. Like buckwheat, basil is also an important crop in today’s world as it can be used in medicine as well as aroma. The results were observed and revealed that the highest salt concentration had the most negative effect on the basil germination. (2017) Both studies support the idea that higher salt concentrations lead to either slower or complete inhibition of seed germination. As for improvements within the study, I believe that it can be tested additionally along with a few changes. For instance, fluctuations in temperature could have affected the number of seeds that germinated. However, this can be controlled in future experimentations by either 8 placing the seeds in a temperature-controlled area or regular observations of temperature such as through a thermostat. Another change that can be made to benefit future research is using various concentrations of the salt solutions rather than only 0.2 M similar to the referenced study on quinoa and other seeds. In addition, since the germination period was set to be six days, future tests could increase the germination period for further observation. Based on the results of the experiment and the mentioned improvements that can be made for future research, understanding the effects of salts on the germination of seeds is essential for future crop growth. Furthermore, since the soil used to grow crops sometimes has high levels of salinity, it is important to develop ways to grow crops that thrive even in the harshest conditions.