8 BULLETIN 1014, U. S. DEPARTMENT OF AGRICULTURE. 



In 1920 eight varieties were grown. The dates of seeding were 

 April 20, May 20, June 24, and July 20. The different seedings were 

 made in single rows 66 feet long and 3.3 feet apart on uniform re- 

 claimed river land that had been cropped to corn the previous year. 

 The stands varied from one plant every 10 inches for the smaller 

 varieties to one plant every 16 inches for the larger varieties. 



A summary of the data obtained from the experiments conducted 

 in 1915, 1917, 1919, and 1920 is shown in Table 2. Data from the 

 experiments conducted in 1916 and 1918 are not included in this 

 summary, as only three seedings were made in 1916, and in 1918 two 

 of the seedings were made in May. 



RESULTS OBTAINED. 



In all the experiments there was a consistent decrease in the 

 number of days from seeding to emergence as the date of seeding 

 was delayed, although frequently the June and July seedings showed 

 such slight differences that they were not recorded. The number of 

 days from emergence to silking and from emergence to ripening 

 consistently decreased except in the July seedings, which tended to 

 show increases as compared with the June seedings. The maximum 

 heights of most of the varieties were attained in the June seedings. 

 The May seedings ranked second, the July seedings third, and the 

 April seedings fourth in height of stalks. 



EFFECTS ON GERMINATION. 



When sown early the short-season northern varieties came up 

 sooner than the varieties from the Central and Southern States. 

 When sown later the differences in this respect usually were not 

 apparent; where differences occurred the early-maturing northern 

 varieties were found to be the first to come up. The results indicate 

 that these northern-grown varieties are capable of starting growth 

 at lower temperatures than the later maturing varieties of the Cen- 

 tral and Southern States. Germination, as would be expected, was 

 much more rapid from the later than from the earlier seedings. 

 Seeds sown in April required an average of 17 days to come up to a 

 stand, whereas those sown in July were as far advanced 6 days after 

 seeding. 



EFFECTS ON HEIGHT AND RATE OF GROWTH. 



The average height of stalk and the average daily increase in height 

 in the different seedings are shown in Table 3. 



The total height and the daily increase in height were greatest from 

 the June seeding. The total height was greater from the May seed- 

 ing than from the July seeding, but the rate of growth was slower. 

 The least height and the slowest rate of increase resulted from the 

 April seeding. 



