FIELD CORN IN MASSACHUSETTS 3 



Corn Varieties 



There are two large groups of corn \arietie.s, one comprising the older, open- 

 pollinated varieties, and the other including the more recently developed hybrid 

 varieties. These two groups differ not onl\- in the manner by which they were 

 developed but also in the methods to be followed in producing stock seed from 

 \ear to year. Most open-pollinated varieties were developed by practical corn 

 breeders who selected the seed from what the}- considered to be the best plants 

 from year to >ear. During the early period of varietal improvement, a consid- 

 erable amount of natural crossing took place between different varietal types. 

 Later on, the breeders began to make careful selection for uniform and productive 

 lines, and gradually developed a large number of varieties with fairly well-defined 

 identifying characteristics. Many of these varieties were outstanding in per- 

 formance, and man}- of them are still being grown. 



It should be pointed out, however, that varietal strains abound which may 

 haxe lost some of the identifying characteristics of the original strain from which 

 they were selected. The relative ease by which the characteristics of an open- 

 pollinated variety may be changed by different growers consistently selecting 

 for different strain types has resulted in the isolation of innumerable strains within 

 all important varieties. Some of these strains may be true to type as well as 

 productive; others may be neither. For example, as shown in Table 2, seven 

 different strains of the variet}- Minnesota 13 were grown at the college in a }-ield 

 trial. There was a difference of two weeks in the time of maturity between the 

 earliest and the latest strains and a difference of 34 bushels per acre in yield 

 between the poorest and the best strains. Growers who want to grow a particular 

 open-pollinated variety should bear these considerations in mind when buying 

 new seed. Unless a reliable, economical seed source is available for the particular 

 strain they wish to grow, the home selection of seed is strongly recommended. 



Table 2. -Performance of Seven Different Strains of Minnesota 13 

 AT Amherst in 1937 



A 

 B 

 C 

 D 

 E 

 F 

 G 



Hybrid corn varieties were developed by men with a scientific background who 

 applied the principles of genetics to the problem of improving corn varieties. 

 In a fairly short time, these men have produced varieties of corn which, under 

 satisfactory growing conditions, surpass open-pollinated strains in productive- 

 ness, uniformity, resistance to disease, resistance to drought, ability to withstand 

 ^ wind, and other important characteristics. New and continually better hybrids 

 2 are being introduced, and it is probable that most of those which are now offered 

 1 for sale will soon be replaced by still better ones. In the light of present knowledge 

 1^ of genetics, the improved corn varieties of the future will be hybrids. 



The term"hybrid" does not refer to a cross between different varieties of corn, 

 ;~ but to a cross between inbred lines or combinations of such lines. A large number 



