EXERCISE 52 



A STUDY OF THE POTATO 



Fig. 67. Desirable and undesirable types of tubers 



Note the sunken eyes, peaked ends, and irregular forms of the lower 

 line of tubers in contrast with the regular outline and smooth sur- 

 face of those in the upper row. (Courtesy of the Pennsylvania 

 State College) 



Statement. Some plants store most of their food in the seed, as in the case of wheat or corn ; others 

 in the stem, as the sugar cane ; others in the leaf, as the cabbage ; others in the roots, as the sugar beet or 



the sweet potato ; others in enlarged underground 

 stems called tubers, as in the Irish potato. 



Object. To study the growth and habits of the 

 potato and to learn how to select and care for seed 

 potatoes. 



Materials. A supply of potato tubers ; a box or 

 pot of potatoes growing from cuttings planted 

 four weeks previously ; some potatoes which have 

 been allowed to sprout in a damp, partially lighted 

 cellar or the school basement. 



. Directions. 1 . Make a study of buds (eyes) and 

 determine if there is a scale or leaf-like structure 

 at the sides of the buds; note its position; note 

 whether the buds are arranged in any regular order ; 

 whether they are equally abundant at both ends 

 of the potato. Make a cross section of the potato 

 and observe the smaller cells which represent the 

 woody stem tissues. Note the arrangement of the 

 starch grains in the tubers. Examine the sprouts 



and the planted potato cuttings; determine, and make sketches showing, how new potato plants 



grow from old ones, and where the young plant obtains its sustenance. 



2. Keep one lot of half a dozen tubers in a warm cellar so that by planting time they have produced 

 long sprouts and keep another lot of similar tubers in a cool cellar so they will remain dormant. Expose 

 the dormant tubers to the light until 

 short sprouts appear. Plant the lots 

 alongside of each other and note which 

 produces the earliest plants, the most 

 vigorous growth, and the largest yield. 



3. Make a collection of the varieties 

 of potatoes commonly grown in the 

 community and grade them according 

 to the commercial grades. Have stu- 

 dents judge them according to the fol- 

 lowing score card. 



Questions. Are the tubers used for 

 planting in your locality home-grown ? 

 If not, where do they come from and why are they the best to plant ? Do the farmers use certified 

 potato seed and why? Where does the potato come in the local crop rotation and why? What fertili- 

 zers are best for potatoes in your locality and what amount should be applied per acre ? 



References. Potato Culture, Extension circular 45, Pennsylvania State College, State College, Pennsyl- 

 vania. Commercial Handling, Grading, and Marketing of Potatoes, Farmers' Bulletin, 753, United States 

 Department of Agriculture. 



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Fig. 68. Potatoes at the time of planting 



The proper condition of the tubers at the time of planting is shown by the speci- 

 mens on the plate at the right ; the vitality of the tubers on the plate at the left has 

 been lowered by the growth of the sprouts. (Courtesy of the Pennsylvania State 



College) 



