EXERCISE VI 



THE EFFECT OF DROUGHT ON GERMINATING SEEDS 



Material. Seeds of clover, peas, beans, alfalfa, cowpeas, corn, 

 wheat, rye, and oats. 



Apparatus. Sprouting-chamber, Geneva seed-tester. 



Germination is often interfered with by the drying out of the 

 soil. The seeds of all dicotyledons suffer considerably from 

 drying out, while the cereals and, in general, the seeds of all 

 monocotyledons suffer but little. There are, however, a few 

 exceptions, as corn, clover, beans, peas, etc. 



1. Count out one hundred seeds each of clover, peas, beans, 

 alfalfa, cowpeas, corn, wheat, rye, and oats. Place them in a 

 Geneva seed-tester and allow them to germinate from twenty- 

 four to forty-eight hours. Now remove the tester from the 

 germinating-chamber, pour out the water, and spread the cloths 

 out so that the seeds will dry for twenty-four hours, or until they 

 are well dried, then pour water in the tester, and again wet the 

 seeds thoroughly and place them in the germinating-chamber. 

 Do this several times and note the results. At the same time 

 carry on a check for each seed which has been treated in the 

 normal way to compare with the others. What difference is seen 

 in the germination ? Do all the seeds respond alike ? If not, 

 why ? What seeds are injured the most by drying out ? What 

 ones are not injured ? Study carefully each sample and deter- 

 mine why some seeds are injured and some are not. Has the 

 construction of the seed anything to do with the drying out? 

 Tabulate and discuss your results fully. 



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