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AGRICULTURE HANDBOOK 495, U.S. DEPT. OF AGRICULTURE 



of varieties will probably continue eases, and low in anthocyanin 



to confound. coloration. Tubers should be short, 



Although there is regional dis- compact, uniform in shape, smooth 



agreement about what traits a skinned, and free of large roots, 



good variety should have, the f ol- Flesh should be essentially free of 



lowing characteristics would gen- pigments, low in oxidation tend- 



erally be considered desirable. The ency, and uniform, with a very fine 



foliage should be vigorous, rela- granular structure. After cooking 



tively resistant to leaf -spot dis- the color should be white or cream, 



Table 1. — Suggested characters for D. alata analysis 



Character Method of rating^ 



Plant characters: 



Anthocyanin in old stem^ 0 to 6. 



Anthocyanin in lower petiole^ 0 to 6. 



Anthocyanin in upper petiole^ 0 to 6. 



Angle of basal veins Estimated, 15° intervals. 



Widest region of leaf Observed. 



Green color intensity of leaf 1 to 6. 



Rugosity of leaf 1 to 6. 



Development of spines 0 to 6. 



Development of wings 1 to 6. 



Petiole length Measured. 



Leaf blade length Measured. 



Width /length ratio of leaf Calculated. 



Presence of aerial tubers 0 to 2. 



Tuber characters: 



Average weight Weighed. 



Type 1 to 5, solitary to multiple. 



STiape 1 to 4, spherical to long. 



Tendency to have neck 0 to 3. 



Tendency to branch 0 to 5. 



Site of branching 0 to 5, head to tip. 



Length Measured. 



Diameter /length ratio Calculated. 



Pinkness of cortex, stem end 0 to 6. 



Anthocyanin2 0 to 6. 



Yellow color 0 to 3. 



Tendency to oxidize 0 to 3. 



Grainy appearance 0 to 3. 



Sting of flesh 0 to 3. 



Acceptability after cooking (appearance) • 0 to 3, not acceptable to pleasing. 



Erosion in cooking 0 to 3. 



Flavor 1 to 3, poor to excellent. 



1 In the numeric scales indicating range of variation within a character, 0 

 designates none or not present and 1 designates lowest or least, unless otherwise 

 specified. 



- Judged by red color. 



