Investigations at Peru, Nebraska. 29 



from 0.5 to 4 inches in length. Infrequently, longer branches were found 

 near the surface, which sometimes had an extent of 1.3 feet. All of the lat- 

 erals were frequently rebranched. It should be noted in this connection 

 that the individual plants were quite variable, both in respect to the size of 

 the tops and the number and extent of the roots. 



This period was rather warm, with a slight excess of cloudiness and 

 humidity. The mean daily temperature was 75® F. and the average daily 

 evaporation 23 c. c. The rainfall for June, although nearly normal in 

 amount, was not well distributed, over half of it falling during the first four 

 days of the month. However, the plants did not lack water. On June 28 

 the available moisture to a depth of 5 feet was 11 per cent. The plants did 

 not recover entirely from the retardation in growth which they underwent 

 during the dry, cold month of May. This resulted in a yield of only 2 or 

 3 tubers per plant, and these were of small size, averaging not over 2 or 3 

 inches in diameter. The whole plat yielded at the rate of only 32 bushels per 

 acre. 



In its early growth the potato had a distinctly superficial system of roots. 

 After extending out horizontally to a distance of 1 to 2.2 feet or more, these 

 same roots then turned more or less abruptly downward and formed the 

 deeper penetrating portion of the system also. This left the subsoil area 

 directly below the plant practically free from its own roots. The individual 

 plants were more variable, both in respect to the size of the top and the num- 

 ber and extent of the roots than were any of the monocotyledonous crops. 



Earlier Investigations of Potatoes. 



Few investigations on the root development of potato are found in a 

 survey of the Hterature. Beckwith (1885) reported that at the New York 

 Experiment Station roots of the White Star potato reached a maximum depth 

 of 1.6 feet and that the horizontal roots were traced to a distance of 2.2 to 

 2.5 feet from the base of the plant. He concluded that most of the roots 

 lay within the first 1.2 feet of soil. Ten Eyck (1899) at Fargo, North Dakota, 

 working with Early Ohio potatoes, stated that the roots during 1898 were 

 few in number and did not penetrate deeply. He washed the roots out of 

 the soil with a jet of water on September 13, at a time when they were partly 

 decayed and, as he states, they made a "bad mess." In 1899 he examined 

 the Rural New Yorker No. 2 potato at the same station and concluded that 

 late-maturing potatoes, of which this variety is an example, "root more 

 freely and more deeply than early potatoes." In this instance he found that 

 the roots reached a depth of 3 feet and that the lateral roots were interlaced 

 between the hills, which were 3 feet apart. He stated that the roots were 

 very tender and were badly broken by washing. In 1900 he again investi- 

 gated the roots of Early Ohio potatoes at Fargo and found that 43 days after 

 planting they lay for the most part within the first 8 inches of soil. A few 

 penetrated to a depth of 1.5 feet and some of the horizontal ones reached a 

 length of 2 feet. Few fibrous roots were found. At maturity the roots had 

 penetrated to a depth of 2.5 feet. Rotmistrov (1909), working at Odessa, 

 Russia, stated that the potato, unlike most dicotyledons, has many main 

 roots, and again at the same station (1914) concluded that the root systems 

 of potatoes are very short, being approximately 2 feet. 



