58 PLANT BREEDING. 



florets are more often fertilized by pollen from neighboring plants than 

 by pollen from the tassel of the same plant, and the individual plants 

 of corn, being of mixed blood, vary greatly. Corn is easily improved, 

 selection and hybridizing being easily and very effectively applied in 

 making new varieties which will suit definite conditions. The care- 

 ful selection of seed in the field by our farmers is changing corn for 

 the better very rapidly. Experiment stations, seed firms, or farmers 

 who wish to enter upon more careful corn breeding, so as to get bet- 

 ter and more rapid results than usual, will find the following plans 

 helpful. 



SELECTING SEED CORN. 



The first selection of corn is made from the field containing the 

 varieties chosen for foundation stock. Since the plant is the unit in 

 breeding, ears are chosen from each of several hundred of the best 

 plants, and the shelled corn yielded by the plant is weighed. Where 

 practicable, nitrogen determinations of the grain from each plant may 

 be made, so as to eliminate in this first selection all those mother plants 

 which are low in their percentage content of protein compounds ; or 

 the percentage of nitrogen may be roughly determined by choosing 

 ears in which the grains appear glutinous rather than starchy when 

 cut across. 



Seeds from 100, more or less, of the best of these plants should be 

 chosen, and the second year a centgener plot should be planted from 

 each. The centgeners are planted in single rows placed side by side, 

 100 hills or more in each. The rows are planted 3^ feet apart, with 

 the hills a foot or more apart in the row. Two seeds are planted in 

 each hill, and when the corn is several inches high it is thinned to one 

 plant in the hill, thus providing each plant with the same room as 

 each other plant. At this point one of several plans may be followed. 



Plom No. 1. — When mature, all plants of each centgener are har- 

 vested and dried, the grain is shelled out, and the grain, cobs, and 

 stalks are separately weighed. These weights are divided by the 

 number of plants actually harvested, to get the average yield of the 

 plants from each mother plant. Notes are made of the character- 

 istics of the plants, as height of ear, height of plant, etc., and an 

 analysis of the mixed grain from all plants gives the yield of nitrogen 

 per plant of each stock; or inspection of the kernels, cut across, show- 

 ing the proportion of dark nitrogenous to white starchy substances, 

 gives a fair index of the content of protein. Only part of the seed 

 from each mother plant having been required for the centgener tests 

 the previous year, there is an abundance of seeds of each of those 

 mother plants which produced superior centgeners for again plant- 

 ing the third year. By planting the corn nursery the third year to 

 centgeners from these best plants the poo: ; ',^ood is discarded and 

 the blood of the best mother plants is i- d. To here further 



