Table 2. — Dioscorea rotundata and D. cayenensis characteristics 

 and rating system — Continued 



Number Characteristic observed Rating system Scale and extremes 



38 Reclassification of 



leaf type — Continued. 



Classified by a non- 

 linear system. 



39 Estimated potential as a 

 cultivated variety. 



Estimated visually 

 from vigor and 

 virus symp- 

 tomology. 



40 Number of tubers per plant • • Estimated as 



tendency towards 

 multiple tubers. 



41 Form of tuber Estimated visually ■ 



42 Tendency of tuber to branch do 



46 

 47 



48 



49 



50 



51 



52 



53 



54 



55 



43 Place where tuber branches Observed 



44 Uniformity of tuber shape 



45 Length of tuber 



Diameter of tuber 



Ratio of tuber diameter to 



tuber length. 

 Rugosity of the tuber 



surface. 

 Hardness of the cortex of 



the tuber. 



Estimated visually 

 when several are 

 compared. 



1 normal tuber, 

 measured. 



do 



Calculated 



Estimated visually 



7 = large but 

 ovate, 



8== long, typi- 

 cal ovate. 

 1 = poor potential, 

 5 - - high 

 potential. 



1 = tubers always 

 solitary, 5 = 

 tubers always 

 multiple. 



1 = spherical, 

 5 = long and 

 narrow. 



0 = no branching, 



5 = highly 

 branched. 



1 = uppermost 



part of tuber, 

 5 == lowermost 

 part of tuber. 



l = not uniform, 

 3 = very uni- 

 form. 



Centimeters. 



Do. 



A ratio usually 



less than 1. 

 1 = smooth, 



3 = rugose. 

 l = soft, 3 = hard. 



Roots on the surface of the 

 tuber. 



Average damage done to 

 tuber surface by insects. 



Intensity of yellow color of 

 cortex. 



Yellow color of flesh of 

 upper part of tuber. 



Yellow color of flesh of 

 lower part of tuber. 



Gradient of color difference 

 from top to bottom. 



Estimated by 



peeling with 



fungus nail. 

 Estimated visually • • 0 = none, 3 = 

 many. 



do 0 = none, 3 = 



extensive. 



do 0 = no yellow 



color, 3 = 

 maximum. 



do Do. 



do Do. 



do 0 = color uniform, 



3 = strong color 

 gradient. 



13 



