48 



ELEMENTS OF AGRICULTURE 



FIG. 28 



Section of a bean- 

 seed showing the coty- 

 ledon, plumule and cau 

 licle which constitute 

 the embryo. Food 

 stored in the cotyledons. 



weeks without having to prepare much food for itself. 

 As the seedling develops, it gradually makes more and 

 more of its own food, until finally the stored food is no 

 longer needed. 



46. Importance of Vigorous Germina- 

 tion. The vigor of the embryo often lim- 

 its the crop that is to be grown. Some 

 kernels of corn germinate promptly and 

 vigorously, others germinate slowly and 

 form weak plants, others fail to germi- 

 nate at all. Often a seed will have vigor 



enough to start germination, but not enough to be able 

 to establish itself in the soil. It is not enough that a seed 

 germinate; it should germinate vigorously. 



47. Germination Tests of Seed Corn. The Iowa Ex- 

 periment Station examined 3,300 samples of seed corn 



for farmers in 1905. Of this number, 

 an average of 19 per cent of the seed 

 was entirely dead, and 21 per cent 

 more was so weak as to be useless, 

 leaving only 60 per cent of good seed. 

 In the same year, counts of the number 

 of stalks per hill were made in over 

 one thousand corn fields. These showed 

 an average of 66 per cent of a stand. 1 

 This may have been an unfavorable 

 season, but every year there is an 

 enormous loss in yield of corn because 

 of dead seed or weak seed. 



The kernels on an ear of corn are usually about equally 



Uowa Bulletin No. 77 



Coafs 



FIG. 29. Section 

 of a kernel of corn. 

 Food is stored in the 

 cotyledon and in the 

 endosperm which sur- 

 rounds the embryo. 



