418 FARM AND SCHOOL PROBLEMS. 



2. An investigation by the Ohio Experiment Station clearly demon- 

 strates the superiority of selected over unselected seed. High-yielding 

 plants were compared with low-yielding plants and unselected stock, and 

 the average yield from 100 hills during the three years of the experiment 

 resulted as follows: 



High-yielding seed 138 pounds 



Unselected seed 110 pounds 



Low-yielding seed 73 pounds 



What was the percent gain in yield of the high-yielding seed over 

 each of the other kinds? 



Exercises. 



PLAT WORK FOR SEED POTATO DEMONSTRATION. 



Plant at least twenty rows of potatoes of the same variety. 

 Number the rows from i to 20. Plant the small seed potatoes 

 in the odd numbered rows beginning with row number I. Plant 

 the large selected potatoes in the even numbered rows. Select the 

 small seed from the small irregular tubers. Select the large seed 

 potatoes from the same bin or basket containing the small ones 

 selected for the experiment. Cut the small tubers into as many 

 pieces as the large tubers are to be cut. A few rows may be 

 planted to small tubers cut in two pieces, to note difference if 

 any occasioned by the size of the cuttings. 



When the potatoes are ripe each row should be dug and the 

 tubers weighed separately. Compare the yield of rows planted 

 with small seed with yield of rows planted with large seed. 



Tabulate results as follows : 



(Taken from an actual experiment.) 



Seed Used. Yield. 



Row 1. Small seed, yield 127 pounds 132.3 bushels per acre 



Row 2. Large seed, yield 160 pounds 166.7 bushels per acre 



Row 3. Small seed, yield 131 pounds 136.5 bushels per acre 



Row 4. Large seed, yield 187 pounds 194.8 bushels per acre 



Points to be observed: 



1. Find the average yield of rows from large seed. 



2. Find the average yield of rows from small seed. 



3. Find the per cent of gain in favor of large seed using the yield of 

 small seed as a base. 



