Jennifer Sarmiento 12/2/17BSGE 11-1Internal Assessment Part 1:Question: What is the effect of salt concentration on the seedgermination of Barley (Hordeum vulgare)?Background Information: In order for a seed to germinate, there aremultiple stages that it goes through. First through imbibition, the seed takesup water, causing the seed to swell and soften. This is a necessary step inorder for the interim or lag phase to occur, in which the seed start to respireand go through life processes such as food metabolism and synthesis ofproteins.
Once the cells in the seed start to divide, the root and radiclesprout from the seed, which from there, the seed develops into a seedling,starting to sprout leaves as the root continues to receive enough water andnutrients (Stivers et.al). Typically, seeds are vulnerable to many factors that couldprevent the seed from going through imbibition or developing into a seedlingsuch as salt (NaCl). Under saline conditions, seeds require higher amount ofwater uptake during germination, since the accumulated amount of salt, asoluble solute, increases the osmotic pressure (Demir et. al). This means thatthe seed will not only be prevented from absorbing water due to the high soluteconcentration surrounding the seed, but it instead will also uptake a great numberof ions from the salt, which can be toxifying for the seed.
Studies have shownthat a high ion content in a plant cell causes changes in protein hydration which restrains enzymeactivity, impairs DNA synthesis and also interferes with mitosis, all of whichcan be harmful as the necessary life processes are being restrained (Waisel,1972). However, there are plants that are moreimmune and tolerant to salts as they have been more exposed to salts and haveadapted to these conditions. These plants are called halophytes, and they incomparison to glycophytes—or the non-salt tolerant plants–deal with the highconcentrations of salt in various methods, one method being able to rupture andrelease the salt back into the environment. One example of a halophyte plant isBarley (Hordeum vulgare) that is a member of the grass family (Poaceae) and it is known for having a high level of salt tolerance.Barley (Hordeum vulgare) is able to withstand a salt concentrationup to 10 g/l, which is considerably more than sensitive crops who can onlywithstand 2.5 g/l (Brouwer et. al).
Furthermore, Barley tends to grow well in cool, dry areas, however it can growin a hot climate, but is more susceptible to diseases and pathogens (Weibe,1979). Despite this, Barley is sensitive to low temperatures and will die ifthe temperature is below 17°F. To continue, Barley grows well between a pHvalue of 6.
0– 8.5 (Weibe, 1979).Statement ofPersonal Interest: I find this experimentinteresting because I want to find out the effectiveness of barley when dealingwith salt. Since I was younger, my mom was always interested in growing plantsand crops, having a skill for always keeping her plants healthy and beautiful.However, I was not the same, mainly because I was not informed of the differentgrowing conditions of plants. This experiment will allow me to continuelearning about this, and expand my knowledge on halophytes.
Independent and Dependent Variables: The independent variable in this experiment is theconcentration of salt in the water for the Barley seeds. This variable will bevaried in the mass of salt, which will be measured in grams, which will beapplied for the water amount, which will be kept constant at 10 ml. There willbe one group in which the salt concentration will be 0 and the other groupswill gradually increase in salt concentrations, up to a concentration of about15 g/l. The dependent variable is the seedgermination of Hordeum vulgare. This can be measured by counting the amount of seeds thatare germinated after 3 days. This then can be converted into a germinationpercentage by calculating the amount of seeds that germinated divided by thetotal number of seeds times 100.Controlled Variables: · Water content: The volume of water that eachseed will be placed in will be at 10 ml in the petri dish.
· Temperature: The seeds that will be germinatedwill be placed in a place at a temperature of 25 degrees Celsius. · Light: All the seeds being germinated will beplaced in a place where the same amount of light is hitting the petri dish.· The space between each seed germinated: Thisspace will be kept constant at 2 inches of space between each seed.
Hypothesis: It is predicted that as the salt concentration in thewater increases, the seed germination of Barley (Hordeum vulgare) will decrease, decreasing at a fasterrate once the salt concentration is higher. Since, under salineconditions, seeds require higher amount of water uptake during germination,since the accumulated amount of salt, a soluble solute, increases the osmoticpressure (Demir et. al). This means that the seed will not only be preventedfrom absorbing water due to the high solute concentration surrounding the seed,but it instead will also uptake a great number of ions from the salt, which canbe toxifying for the seed. This will then lead to a restraint in enzyme activity, impair in DNA synthesis andmitosis, affecting the necessary life processes are being restrained (Waisel,1972).
However, since Barley tends to grow in a drier area, its germinationrate is predicted to not be as low in comparison to other plants, since it doesnot need to absorb as much water as other plants. This means that the Barleyseed is not as likely to absorb as much of the ions from the salt, whichdecreases the chances of the Barley seed to be impaired in the life processesin comparison to other plant seeds. BibliographyBARLEY: Origin, Botany, Culture,Winter Hardiness, Genetics, Utilization, Pests. (n.d.). Retrieved December 2,2017, from https://naldc.nal.
usda.gov/download/CAT79716376/P Brouwer, C., Goffeau, A., &Heibloem, M. (1985).
Introduction toIrrigation (Provisional ed.). FAO Land and Water Development Division. Demir, I., & Mavi, K. (n.d.
).Effect of salt and osmotic stresses on the germination of pepper seeds ofdifferent maturation stages. Retrieved December 02, 2017, fromhttp://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132008000500004 Wiebe, G.A.
1979. Introduction of barley into the new world.In: Barley: origin, botany, culture, winter hardiness, genetics utilization,pests. USDA Agriculture Handbook 338. Washington, DC. Stivers, L., & Dupont, T.
(2017, November 13). Understanding Seeds and Seedling Biology. RetrievedDecember 02, 2017, from https://extension.psu.edu/understanding-seeds-and-seedling-biology Waisel, Y.
(2012). Biology of halophytes (1st ed.).Burlington: Elsevier Science.