30 ELEMENTS OF AGRICULTURE 



saved for seed. These will have to be raised another 

 year before there will be enough for a field. The process 

 may be repeated for further improvement. 



30. Other Self -fertilized Plants may be improved in 

 the same manner: 



(1) Select the best. 



(2) Test the yielding power. The seed from those 

 that yield most is saved for field planting. 



Wheat, rice, peas, beans, are commonly self-fertilizing. 



31. Potatoes are propagated by cuttings. The potato 

 tuber is a much-enlarged underground stem. The eyes 

 are really buds. Propagation in this way is asexual. When 

 a good potato is secured, it is multiplied from cuttings. 



The only satisfactory way to improve potatoes by selec- 

 tion is by hill selection. What is necessary for a good yield 

 is good hills. If a large potato is selected from a bin of 

 potatoes, it may have been the only good potato in the 

 hill. If potatoes are dug by hand, the best hills may be 

 saved while digging. If they are dug with a machine, 

 the most promising hills may be dug by hand before dig- 

 ging the field. The ones that produce the largest yield 

 of desirable potatoes are saved for seed. Enough may be 

 saved in this way so that they will produce seed for the 

 entire field the second year following. It is also desirable 

 to keep each hill separate and to plant separately. In this 

 case, the ones that yield most are kept for the breeding 

 plot. 



32. How Often Do Potatoes Need to Be Grown from the 

 Seed-ball? Potatoes also reproduce by seeds from the 

 seed-balls. But the number of these seeds is now small. 

 Probably, the potato that produced fewest seeds has been 



