EXERCISE VII 



SEEDS TREATED WITH CHEMICALS TO HASTEN GERMINATION 



Material. Seeds of the honey locust, asparagus, wheat, barley, 

 oats, rye, radish, cabbage. 5, 10, and 50 per cent and concen- 

 trated 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, 

 sprou ting-chamber. 



The treatment of seeds with chemicals has long been known, 

 but definite information concerning the exact effect of such treat- 

 ment 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. 



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