TESTS IN MARYLAND. 11 



CROSSING THE VARIETIES. 



Selection 119, which has been undergoing improvement for 10 

 years by tlie ear-to-row method of breecHng and adaptation to con- 

 ditions of the Potomac River soils near Washington, was chosen as 

 the male parent, and the crossed seed was obtained by planting one 

 of the other varieties in every third row in a field of this variety 

 located 3 miles south of Washington, D. C, on a small tributary of 

 the Potomac. As soon as the tassels appeared they were removed 

 from all the varieties, so that no pollen matured in the field except 

 on the rows of Selection 119, which fertilized the silks of all the other 

 varieties, forming the supply of crossed seed, the productiveness of 

 which was compared in 1910 with pure seed of the parents. About 

 30 of the best ears from these detasseled rows were chosen as seed for 

 these tests. These ears were shelled, making a composite sample of 

 each crossj which was used in planting all of the tests. 



A supply of the original seed of all the varieties used in making 

 these crosses was retained in the seed-corn room of the Department of 

 Agriculture according to the best known methods of seed preservation. 



GROWING PURE-BRED SEED FOR COMPARISON. 



In order that the tests of productiveness might not be restricted to 

 the old seed of the parent varieties, isolated plats of eight of the 

 varieties, including the male parent — Selection 119 — were grown in 

 1909 from the original seed. These 1909 plats were grown in the same 

 localities and under the same conditions as the original seed. 



WORK OF 1910. 



LOCATION OP TESTS. 



Duplicate tests of productiveness were made at Derwood and at 

 Pike Crossing, Md. Derwood is located about 16 miles northwest of 

 Washington, where the soil is of a red-clay, flint-stone nature, and the 

 two tests were located on similar soil. Pike Crossing is situated about 

 5 miles north of Washington, where the soil is of a mica, red-clay 

 nature. At Pike Crossing the two tests adjoined, but the first test 

 was located on land that had been in sod for some 10 years or more, 

 while the duplicate test was located on impoverished soil that had 

 grown truck crops for fully as many years. At these points the 

 season of 1910 was unusually dry and unfavorable for com. 



ORDER OF PLANTING THE TEST ROWS. 



In order to have the means of comparing the productiveness of the 

 crossed seed grown in 1909 with seed of the parents grown the same 

 season and with the original seed of the parents used in making the 

 crosses, the plantings were made in the order shown in Table II. 



218 



