1. Serial Dilutions

2. Cut piece of paper towel and insert into bag
Get 2 x 3 inch jewelry bags
jewelry supply store.  See product # on second
Cut piece of paper towel and insert into bag
Staple across the bag such that there is space for roots to grow
Add 10 to 15 seeds to each bag

3. Make a 0.2-g/mL NaCl STOCK solution
- Add 2 g of sodium chloride to beaker and add water to 10 mL
0.2 g/mL NaCl
Stock Solution

4. Get as many test tubes (minus two controls) as you have plastic jewelry bags for your experiment

5. Add 5 mL of water to each of you test tubes

6. Add 5 mL of Stock Solution to first test tube.

7. Mix the first Tube

8. Take 5 mL of first tube and add to second tube

9. Mix

10. Repeat and remove 5 ml from last tube and discard

11. Using a 5mL disposable pipette, add 3 mL from stock solution to a bag, 3 mL of water to a bag, and the 3 mL from each test to its respective bag

12. Stock Solution

15. Water

18. 0.1 g/mL Solution

21. 0.05 g/mL Solution

24. Etc.

25. Put all the bags upright in the beaker that had the stock solution.
Put in dark area for one about one week
Determine the percent dead for each concentration.
Graph with the % dead on the y-axis and concentration on the x-axis.
Determine the LD50 or the concentration where 50% of the seeds did not germinate

26. Percentage of population killed by a given dose
100 75 50 25 2 4 6 8 10 12 14 16
Percentage of population killed by a given dose
Dose (hypothetical units) LD