DEVELOPMENT OF TUBERS IN THE POTATO. 



23 



IX, particularly in the averages of the data obtained in 1917. The 

 variation in tuber production according to variety is there clearly 

 shown, the number of tubers per hill ranging from 3.8 in the Rural 

 New Yorker to 7.1 in the Charles Downing. The lowest average 

 weights per hill were produced by the two early varieties, Triumph 

 and Early Ohio, and the highest by the Pearl, which is a late variety. 



Table IX. — Effect of irrigation on the average number and the average weight of the tubers 

 of different varieties of potatoes grown at Greeley, Colo., in 1917 and 1918. 





Number of tubers per hill. 



Weight of tubers per hill (grams). 



Year and variety. 



No irri- 

 gation. 



First 

 irriga- 

 tion 

 after 

 tubers 

 had 

 begun 

 to set. 



Irrigation 

 started before 



tubers had 

 begun to set. 



Aver- 

 age. 



No irri- 

 gation. 



First 

 irriga- 

 tion 

 after 

 tubers 

 had 

 begun 

 to set. 



Irrigation 

 started before 



tubers had 

 begun to set. 



Aver- 





Medium 

 number 

 of irri- 

 gations. 



Many 

 irriga- 

 tions. 



Medium 

 number 

 of irri- 

 gations. 



Many 

 irriga- 

 tions. 



702.0 

 1,145.0 



811.3 

 1,137.7 



884.7 

 868.3 

 926.7 



age. 



Experiments in 1917: 



Triumph 



Early Ohio 



Charles Downing 

 Pearl 



4.4 

 3.2 

 5.1 

 5.3 



3.5 

 3.6 

 4.5 



3.9 

 4.2 

 7.1 

 5.1 



3.2 

 4.2 

 5.6 



7.8 

 6.3 

 9.4 

 6.2 



4.3 

 6.5 

 6.9 



,5.9 

 6.7 

 6.6 



7.7 



4.2 

 6.2 

 9.0 



.5.5 

 4.8 

 7.1 

 6.1 



3.8 

 5.1 



6.5 



459.8 

 413.0 

 446.3 

 528.0 



533.5 

 425.7 

 433.7 



697.2 

 712.3 

 830.3 



887.8 



759.8 

 826.7 

 867.0 



1,060.7 



928.3 



1,005.7 



1,036.3 



876.7 

 974.3 

 991.3 



729.9 

 730.6 

 773.4 

 897.5 



Rural New- 

 Yorker 



Russet Burbank. 

 Peachblow 



763.7 

 773.8 

 804.7 



Average 



4. 2 1 4. 8 



6.8 



6.6 





462.9 



797.3 981.9 



92.5. 1 





Experiments in 1918: 



Triumph 



Late Ohio 



Charles Downing 

 Pearl 



3.6 

 3.3 

 5.1 

 3.3 



3.4 



3.1 

 3.1 

 5.0 

 3.5 



3.8 



3.1 

 3.0 

 6.5 

 3.3 



4.3 



3.6 

 3.6 

 6.6 

 3.7 



4.0 



3.4 

 3.5 



5.8 

 3.5 



3.9 



269.0 

 374.2 

 342.9 

 399.2 



324.3 



266.3 

 482.2 

 420.5 

 490.3 



475.4 



317. 5 

 675.9 

 589.7 

 610.1 



645.5 



365.1 

 654.1 

 655.9 

 676.3 



652.3 



304.5 

 546.6 

 502.3 

 544.0 



R ural New 

 Yorker 



.524. i 



Average 



3.7 



3.7 



4.2 



4.3 





341.9 



426. 9 567. 7 



600.7 j 



CHARACTER OF SOIL AS RELATED TO TUBER PRODUCTION. 



In 1918 experiments were conducted for the purpose of determining 

 to what extent, if any, tuber production is influenced by the type of 

 soil. Two varieties, the Triumph and the Rural New Yorker, were 

 used for these studies. The seed for each variety, which was obtained 

 from a single source, was divided into three lots. One lot of each 

 variety was grown on the farm of Mr. W. M. Wilson,'* on a very heavy 

 clay soil classified as ''Billings clay loam (3) ;" a second lot was grown 

 on the experiment station farm on a clay-loam soil designated as 

 " Fort Collins loam (3) ;" the remaining lot was grown on the farm of 

 Mr. W. R. McClellan ^ on a sandy loam known as "Colorado fine 

 sandy loam (3)." 



The crops on all plats were grown under practical lield conditions, 

 the cultivation and irrigation practices following the methods in gen- 



*The writer is indebted to W. M. Wilson and W. R. McClellan for their cooperation in growing the 

 experimental crops produced on the heavy clay and fiue sandy loam, respectively. 



