56 CORN 



"Well matured corn two years old is very slightly weakened if kept 

 in cool dry storage. Corn four years old shows very weak germina- 

 tion, much of it failing to grow at all."* 



MOISTURE. A dry seed is usually hardy. It withstands the 

 extremes of heat and cold. The structure of a matured corn kernel is 

 conducive to the absorption of water, the first process in the awaken- 

 ing of the embryo. Water has four distinct functions in germination. 



(1) It softens the covering of the seed. It penetrates the minute 

 cells of the seed coat, enters the larger cells within, and by swelling 

 them causes the entire seed to increase in size and ruptures the 

 softened covering. 



Kernels of corn placed in water at a temperature of 70 degrees 

 Fahrenheit will absorb 15 per cent of their original weight in 52 

 hours. The rapidity of absorption depends upon the maturity of the 

 corn and temperature of water. Kernels with a Jarge amount of flinty 

 starch and covered with a thick coating of horny gluten, which acts 

 as a sealing wax, require considerable time and a higher temperature 

 to induce penetration of moisture. Starchy kernels of an open cellular 

 structure admit the soil moisture very readily. This accounts for the 

 rotting of immature kernels when placed in the ground early in the 

 spring, ac which time it is cold and wpt. 



(2) It dissolves the plant food. The parent bequeaths to the 

 ripened ovule a store of starch, fat, sugar, and protein before the 

 seed is cast off. Of these substances the sugar and allied compounds 

 are soluble in water; before the remainder can be utilized they must 

 be digested or rendered soluble. This digestion takes place, how- 

 ever, only in the presence of water. This fact is well illustrated by 

 the rapid germination of immature kernels of corn. The sugar which 

 would later have been changed to starch and stored in the kernel, is 

 readily soluble in the water which first enters. Tests have shown 

 that corn which was picked early, germinated in a shorter time than 

 that p^athered in the husking season. However, it must be borne in 

 mind that there is a smaller reserve of plant food in such a kernel t*^ 

 continue the germination. Therefore, the soil must be warm and 

 rich in order that the young rootlets may begin immediately to draw 

 from outside sources. 



(3) It carries the plant food to the growing embryo. A con- 

 tinual supply of available nutriment is demanded by the young plant. 

 The presence of water insures its transportation to every growing 

 point. The scutellum acts as an absorbing organ for the plant food 



*Classbook of Botany. Wood. 



