12 



MASS. EXPERIMENT STATION BULLETIN 432 



Havana K2 was bred and developed in Massachusetts. The original cross 

 from which it was obtained was a cross of regular Havana Seed known locally as 

 the Sandman strain onto Havana 2n. Havana K2 (see figure 2) was developed 

 from a selection made from the backcross of first generation plants of the original 

 cross and the regular Havana Seed parent. Havana 211 is resistant to black root 

 rot. The Sandman strain of regular Havana Seed was highly acceptable in t\pe 

 and qualitx'. 



In niaking comparative studies of the plant type of Havana 211 and the strains 

 used as controls, twenty plants per strain were measured during each of two years. 

 The plants were topped at the internode just below, the lowest leafless sucker or 

 spike and allowed to mature for harvest. The leaves were counted later. Three 

 leaves were taken from the corresponding middle part of the plants of each strain 

 for measurement of leaf shape. The remaining leaves were removed and measure- 

 ments nuide ol the standing stalks. 



The average measurements of different characteristics of plant type of Havana 

 211, Havana 142, and regular Havana Seed (Brown Strain) are given in Table 2. 



Table 2. — Aver.a,ge Measurements of Characteristics of Plant Type 

 OF Regular Havana Seed (Brown Strain), Havana 211, and Havana 142. 



The measurements for comparing average leaf shapes of the different strains 

 were made by using a measuring board constructed specially for the purpose. 

 The plan of the board consisted of a horizontal a.\is from whose center radii were 

 drawn at angles of 5, 10. 15, 20, 25, 30, 45, 65, 90, 115, 135, 150, 155, 160, 165, 170 

 and 175 degrees. In using this board, the midrib of the leaf was held on the 

 horizontal axis of the board with the center of the mitlrib at the center of the axis, 

 and measurements were taken from the center to the outside edge of the leaf 

 along each of the sexenteen radii. Three other measurements were made of each 

 leaf: length along the midrib, width at the place of greatest width, and width 

 ol the butt. 



The diagrams of the comparative leaf shapes of Havana 211 and a strain of 

 regular Havana Seed (Brown Strain) were plotted from proportionate reductions 

 of average measurements of leaf characteristics. (See Diagrams 1 and 2.) 



