296 STATE BOARD OF AGRICULTURE. 



The standard variety or check occupies the real (interior) edges of each 

 section of the variety series, and is repeated on each fourth (or at least 

 fifth) plat throughout the series. 



At harvest time the yields are obtained carefully for each plat in the 

 series. The interpretation of these results depends upon the yields of 

 the standard, as found on the check plats, and as calculated for the other 

 plats by interpolation,' The coefficient of yield' (calculated for each plat) 

 is the quotient of the actual or found yield of the variety growing there 

 divided by the calculated yield of the standard for the same plat. Or. 

 considering the standard as 100% these coefficients of yield are the decimal 

 expressions of the per cents that the varieties in question bear to that 

 of the standard variety. An average is now taken between the two 

 duplicate coefficients of yield obtained for a variety, in the same year. 

 As these figures are based on unity, they are not influenced by the varia- 

 tions in the jdeld of the standard from year to year now on different soils. 

 This makes it possible to average the yearly results, as long as they run 

 without danger of obtaining a weighted average. 



In all this class of work, the series planted in the earlier years include 

 unimproved varieties of unknown value, but as time goes on the poor 

 yielders are excluded and little by little improved varieties take their 

 place. 



BEDS, CENTGENERS, AND INDIVIDUAL PLANT RECORDS. 



The individual seeds are planted far enough apart so that the roots 

 will not interlock during growth, and at approximately equal distances 

 that the individual plants may have equal chances to develop. In case of 

 corn and beans the seeds are dropped by hand in rows of the ordinary 

 field width. In the case of alfalfa the seed is planted in beds too thick 

 for more than six weeks development. The better plants are then trans- 

 planted to positions three by three feet in the nursery which is a centgener 

 in a plant-row series when the seed comes from a selected individual 

 plant. The difference between a bed and a centgener is that the bed is 

 planted from a lot of seed that is not a progeny. It may be commercial 

 seed. A centgener is a progeny plat planted from the seed of a single plant. 

 Beds and centgeners are planted by what is known as the centgener 

 method of planting. . ?>»<«» 



In the case of small grains, the seeds are usually dropped five by five 

 inches apart by means of a special centgener planter in belts twelve plants 

 (five feet) wide. 



The more promising plants are selected out of the beds to become 

 mothers of plant-rows, if they are homozygous, or they are planted in 

 centgeners if thought to be heterozygous. The seed of superior plant-rows 

 together with the centgeners, that did not segregate, are tested further 

 in variety series. 



Individual plant records are made with all of the plants in a perennial 

 nursery like alfalfa where the results are not obtainable in any one year 

 and selections can not be made until all of the results are together. 



In the case of centgeners originating from crosses, the plants are classi- 

 fied into their phenotypes and counted. Then the superior individuals of 

 each phenotype are tied up separate^'' and taken to the laboratory for in- 

 dividual plant notes. Sometimes the segregations are such that a full 

 classification can not be made until the plants are threshed individually 



