34 TOBACCO BREEDING. 



In all the varieties of tobacco which the writers have improved by 

 seed selection and breeding the internodes are short and the number 

 of leaves proportionally greater in the improved strains. In a care- 

 ful count of the number of leaves to the plant in a good field of 

 Sumatra tobacco the average was found to be between 19 and 20, 

 while the records made in the breeding plats of strains of tobacco 

 originally grown from the same seed as the general field where these 

 leaves were counted show that the number of leaves was increased by 

 two years' selection to an average of between 23 and 24. The breed- 

 ing plats and the general field were grown under exactly the same 

 conditions in order to eliminate any influences outside of the results 

 of careful seed selection for the production of a greater number of 

 leaves. The leaves produced on the plants giving an increased num- 

 ber were equal in size and more desirable in shape than those from 

 stalks producing a smaller number. 



The increase in yield due to the production of a greater number of 

 leaves on individual plants and to shortening the internodes may be 

 secured by systematic seed selection with no additional cost to the 

 grower. Aside from the increase in yield, the quality of the leaf when 

 there is a large number of leaves borne by the stalks is usually better 

 than when the stalks produce but few leaves. This is particularly 

 true in cigar and high-grade smoking* tobaccos. None of the im- 

 proved types of Sumatra tobacco have leaves sufficiently close together 

 to cause any deterioration in the quality or texture of the leaf during 

 the curing process. In the case of certain types of export and plug 

 tobaccos and in some of the northern-grown cigar-tobacco varieties 

 an increase in number of leaves is not desirable, for the reason that it 

 is conducive to pole-sweat when the crop is being cured. It is further 

 true in the case of these varieties that if the number of leaves is in- 

 creased without shortening the internode. the plants will become too 

 tall for expeditious handling. Therefore, it is necessary in certain 

 varieties of tobacco to keep the leaves down to a certain definite num- 

 ber, with a desirable length of internode. 



It is entirely possible for the grower to control largely the number 

 of leaves by careful seed selection and in this way produce uniformly 

 the plants which give the number desired. Care must always be taken 

 in selecting for a large number of leaves not to increase the number 

 at the expense of leaf uniformity. Only plants having leaves uni- 

 form in size and shape should be selected for seed purposes, and this 

 selection must be kept up with unremittent persistency from year to 

 year in order to hold constant the characters of improved strains of 

 tobacco after they have been produced. 



A large number of leaves to the plant is almost invariably closely 

 correlated with a much lessened tendency to sucker and with de- 



96 



