Yujin LeePeriod 7

24 January 2012

Salinization Lab Group #6

Purpose: The salinization lab simulates how the salinity affects the germination and growth of black eyed peas by using serial dilution, determining what the LC-50 would be.

Hypothesis: If the black-eyed beans successfully germinate in some bags with different concentration of salt (NaCl), then when we collect the data of the growth and number of germinated beans in the bags, we will find that the beans will mostly germinate in bags with lower concentration (Bags #7-#10) of salt (NaCl).

Materials: Salt (NaCl), black-eyed beans, paper towels, Ziploc bags, glass stirrer, graduated cylinders, two 50-mL beakers, eight test tubes, test tube rack, weighing dish, balances, disposable pipette, tweezers, stapler, distilled water, Sharpie, and labeling tape.

Procedure: First, our group measured 2 grams of salt (NaCl) on the balances using weighing dish, inserted the salt into one of the 50-mL beaker, added 10 mL of distilled water, and stirred the stock solution (20%) with the glass stirrer until the salt dissolved thoroughly. Then we labeled ten Ziploc bags one through ten, cut ten same pieces of paper towels, damped each paper towel equally, and inserted paper towels into each one of the bag. After, we stapled across each of the bags horizontally such that there is enough space for roots to grow but beans don’t fall through the line of staples. Then, we added ten black-eyed peas to each of the bags, making sure all the beans were not damaged. We gathered eight test tubes and added 5 mL of distilled water to each of them. After, we added 5 mL of the stock solution (20%) and mixed the first tube. Then afterward, we got 5 mL from the first test tube and added it to the second test tube and mixed the two different solutions completely. We continued this process and repeatedly removed 5 mL of mixed solution from the previous test tube and placed in the next test tube. In the last test tube, with the 5 mL of extra solution, we discarded it. After mixing all of the saline solutions, using the pipette, we added 5 mL of stock solution to Bag # 1 (20 %), 5 mL of distilled water to Bag # 10 (0 %), and 5 mL of mixed solutions from each of the eight test tubes to the corresponding, labeled bags (#2-#9). After we put all the solutions into its corresponding bags, we sealed the bags completely, and placed them in dark area. Then our group would check the beans periodically to count the number of germinated beans, measure the growth of the beans, and record all the data into the chart.

Standards: Size and type of black-eyed beans, size and type of bags, volume and type of water, type of salt (NaCl), size, type, and moistness of paper towels, and classroom temperature and location of the bags.

Controls: Bag #1 (20% stock solution) and Bag #10 (0% distilled water solution)

Variables: Concentration of Salt (%)

Data Tables:

Day 0: Day 1:

Bags (#)

Salt Concentrati

on (%)

Germinated Beans (#)

Growth (cm)

1 20 0 02 10 0 03 5 0 04 2.5 0 05 1.25 0 06 0.625 0 07 0.3125 0 08 0.15625 0 09 0.078125 0 010 0 0 0

Day 2: Day 7:

Bags (#)

Salt Concentration

(%)

Germinated Beans (#)

Growth (cm)

1 20 0 02 10 0 03 5 0 04 2.5 0 05 1.25 0 06 0.625 0 07 0.3125 0 08 0.15625 0 09 0.078125 0 010 0 0 0

Graphs:

Bags (#)

Salt Concentration

(%)

Germinated Beans (#)

Growth (cm)

1 20 0 02 10 0 03 5 0 04 2.5 0 05 1.25 0 06 0.625 0 07 0.3125 2 1.48 0.15625 2 1.79 0.078125 5 3.610 0 4 3.6

Bags (#)

Salt Concentration

(%)

Germinated Beans (#)

Growth (cm)

1 20 0 02 10 0 03 5 0 04 2.5 0 05 1.25 4 4.36 0.625 9 37.17 0.3125 2 85.38 0.15625 2 76.19 0.078125 5 84.110 0 4 72.8

Analysis Questions:

1) What relationship is there between the number of seeds that germinated and the salt concentration of the water? The relationship is that if the salt concentration of the water is higher in the bags, the number of germinated beans is lesser. The bags with higher salt concentration (#1-#4) didn’t have any germinated seeds, but the bags with lower salt concentration (#4-#10) had at least two germinated seeds or more.

2) What is the effect of salt concentration and overall growth? The effect of salt concentration is that if the salt concentration of the solution is higher, the overall growth would be lower or there would be no growth at all. For example, the last data our group collected shows that there was no growth for Bags #1-#4 (20%-2.5% NaCl solution), but starting from Bag #5, the growth significantly increased as the salinity of the solution decreased.

3) Are your results applicable to “real life”? Why or why not? Yes, my results are applicable to real life because this lab demonstrated how the salinity affects the farming and how much salt concentration would allow the crops to grow; therefore, for humans’ survival, we need successful farming in order to produce enough food or crops. The result also indicates that even small amount of salt concentration can decimate the growth of the plants; therefore it is necessary for farmers to prevent the future damaging of soil so that we can promote better seed germination.

Conclusion: From this lab, I learned that the soil salinization becomes a serious threat to agriculture because when a field is irrigated with water containing dissolved water, much of the water evaporate, leaving the salts behind as a thin layer on top of the soil. Eventually, salts will build up on field overtime until the soil is so damaged that seeds will no longer germinate in the soil. The lab results prove my hypothesis to be partly true. My hypothesis was that beans will mostly germinate in bags with lower concentration of 0.3125% to 0% (Bags #7-#10) of salt (NaCl); in fact, the beans germinated in bags containing salt concentration of 1.25% to 0% (Bag #5-Bag #10). Also, the lab helped the understanding of the LC-50, the lethal content at 50%, meaning the level of salinity lethal to half of the sample population (black-eyed beans). The errors that might have occurred during the lab are process of dilution and soaking paper towels. While we were diluting, there might have been some inaccuracy in the amount of solution into the beakers because of the pipettes. Also, once we put the solution from the test tubes onto already soaked paper towels, the salt concentration would have decreased significantly, even if the concentrations of solution in the test tube were correct. In order to improve future lab, we should not soak the paper towel so that the salinity levels would not vary. This lab helped me to understand the importance and effects of soil salinization; the society should conserve our soil to prevent soil salinization so that we can prevent further damages of soil, which can lead to less germination of seeds.