EFFECT OF DATE OF SEEDING ON CORN. 9 



Table 3. — Total height and average daily increase in height of corn at the Arlington Ex- 

 perimental Farm, near Washington, D. C, when planted on different dates in 1915, 

 1917, 1919, and 1920. 





Emer- 

 gence 

 to full 

 growth 



(days). 



Height of stalks 

 (inches). 



Date of seeding. 



Total. 



Average 



daily 

 increase. 



Apr .19 



63 

 51 

 45 

 43 



75.6 



86.4 

 88.8 

 76.8 



1.20 



May 20 . ' 



1.69 





1.97 



July 20 



1.79 







EFFECTS ON DEVELOPMENT. 



The number of days from emergence to first silks decreased as the 

 date of seeding was delayed from April to July. The number of 

 days from emergence to ripening also decreased except in the case 

 of the July seedings. These showed an increase as compared with 

 the June seedings. Development to the silking stage was more 

 rapid as the date of seeding was delayed. The plants from the 

 April seeding required 63 days from emergence to reach the same 

 stage of development which those from the July seeding attained 

 in 43 days. 



The duration of the pollen-shedding period depended upon the 

 degree of inherent variation within the variety, the lack of uni- 

 formity in coming up, the amount of suckering, the variation in 

 the fertility of the soil, and weather conditions. How these various 

 factors might influence the duration of pollen shedding in a variety 

 is evident and need not be treated in detail. Except under unusual 

 conditions, the experiments indicate that the duration of this period 

 is longer in plants from the earlier seedings than in those from the 

 later seedings. The average for the plants from the April seedings 

 was 22 days; May, 19 days; June, 18 days; and July, 17 days. 



CORRELATION OF EFFECTS. 



It is of interest to know how closely the difference in number of 

 days between the dates of seeding corresponds with the differences 

 between dates of emergence, dates of first silking, and dates of 

 ripening. The average results from all the experiments are shown 

 in Table 4. 



As the date of seeding was delayed the differences in the time of 

 emergence, silking, and ripening more nearly approximated those 

 in the date of seeding. 



In the comparison of April and May seedings a difference of 32 

 days in time of seeding represents a gain of 14 days in time of ripen- 

 ing. May 20, however, is later than the usual date of seeding in 



