Material. Seeds of the honey locust, asparagus, wheat, barley, oats, rye, radish, cabbage. 5, 10, and 50 per cent and concentrated sulphuric acid, saturated solution of limewater, 2 per cent solution of iodine, saturated solution of chlorine water, 1 per cent monobromide of camphor.

Apparatus. 100-cc. wide-mouthed bottles, Geneva seed-tester, sprouting-chamber.

The treatment of seeds with chemicals has long been known, but definite information concerning the exact effect of such treatment on germination is meager and based on three hypotheses.

Hypothesis 1. If seeds are treated with acids, the hard seed coat is loosened, which makes possible the more rapid imbibition of water.

Count out five lots of ten seeds each of the honey locust and asparagus and proceed as follows: Place the seeds of each lot in a small, wide-mouthed bottle and immerse four of them each respectively in 5,10, and 50 per cent dilutions of sulphuric acid and in the concentrated acid for thirty minutes. Place them in the Geneva seed-tester and germinate. Use one lot untreated to serve as a check. Tabulate the results every twenty-four hours on both treated and untreated seeds. Describe what action the acid of different strengths has on the seeds. What per cent of acid gives the best result? What per cent solution would you advise? Are both kinds of seed acted upon alike by the same solution? Plot a curve showing the increase in the time of germination over the nontreated seed. Use colored inks to show the difference in the time.

Hypothesis 2. If the evolution of carbonic acid gas can be hastened by the use of chemicals, germination will be facilitated.

Count out ten lots of one hundred seeds each of wheat, barley, oats, and rye. Place one lot of each seed in a 100-cc. wide-mouthed bottle, cover the seeds with a saturated solution of lime-water, and allow them to remain immersed for thirty minutes.

Seeds Treated With Chemicals To Hasten Germination. Student's Notes And Report

Curve tor Acid Treatment

No. of seeds

100 90 80 70 60 50 40 30 20 10 0

Days

1

2

3

4

5

6

7

8

9

10

Curve for Limewater Treatment

No. of seeds

LOO 90 80 70 60 50 40 30 20 10 0

Days

1

2

3

4

5

6

7

8

9

10

Note. Use colored inks, as, for example, red ink = canna seed, black ink = asparagus, blue = check; or use the following symbols:____= canna seed,----------= asparagus,-----------= check, etc.

Now place the seeds in a Geneva seed-tester and germinate. The second lot of seeds should be germinated untreated in the same tester, under the same conditions, to serve as a check. Tabulate your results and describe fully what takes place. Plot a curve to show the increase in germination of seed that has been treated over seed that has not been treated.

Hypothesis 3. If you can set oxygen free, to unite with the carbon of the seed and thus form carbonic acid gas, which must pass off, germination will be hastened.

a. Count out one hundred seeds each of the radish, cabbage, and onion, and place each in a wide-mouthed bottle. Now cover them with a 60 per cent alcoholic solution of iodine (approximately 1.1 per cent solution) and allow the seed to soak or be kept moist with the solution until germination begins. Note the time of sprouting. Tabulate your results to show the increase in time. Discuss.

b. Count out four lots of one hundred seeds each of the radish. Place each lot in a bottle and keep the first moist with pure water, the second with a 60 per cent alcoholic solution of iodine, the third with a saturated solution of chlorine water (approximately 1.8 per cent), and the fourth with a 1 per cent solution of monobromide of camphor. Describe fully what takes place and tabulate your results. Plot a curve to show what effect the different chemicals have on the germination of the radish seeds.

Seeds Treated With Chemicals To Hasten Germination. Student's Notes And Report

curve to show Radish Germination

No. of seeds

100 90 80 70 60 50 40 30 20 10 0

Days

1

2

3

4

5

6

8

9

10

Note. Use different-colored inks or different symbols to represent the different solutions.