230 



Bulletin 230. 



of the soil. Nine per cent of the plants planted at a depth of two 

 inches bore tubers upon the stem above ground, while none were 

 thus borne by those planted at depths of four and six inches. 



It will be observed that the majority of tubers were produced at a 

 depth of two to five inches, and these were also of most desirable 

 shape and size. The tubers growing in depth from two to five 

 inches are superior in quality to those shallower or deeper. Those 

 found nearer the surface than two inches were usually of inferior 

 color and were elastic and tough in their texture, remaining soggy 

 and heavy after boiling. Those deeper than four inches were often- 

 times watery and seemed to be immature both in regard to starch 

 development and cellular structure. By average, they were also 

 smaller. 



It should be noted further that the plat upon which tubers were 

 planted at six inches in depth yielded best, both as regards number, 

 size, shape and weight of large tubers. It is true, too, that the 

 tubers of this plat were superior in quality, as is shown by the table 

 below. 



Our investigations have not yet gone far enough to enable us to 

 say what is the optimum temperature, either in the soil or in the air, 

 for the best growth and development of the potato. The experiments 

 seem to bear evidence, however, that the temperature of the soil in 

 which the potatoes grow has some influence upon the quality. The 

 ratings of quality, the number, weight and percentage of potatoes 

 planted at different depths, are shown in the following table: 



Table Showing Degrees of Quality According to Depth Planted. 



