1905.] IMPROVEMENT OF TOBACCO BY SEED SELECTION. 1 89 



THE EFFECT OF AGE ON THE VITALITY OF THE SEED. 



The vitality of tobacco seed is preserved for several years, 

 and is apparently as good for producing vigorous plants as 

 when harvested. However, it has been demonstrated that very 

 old seed has very weak vitality and produces weak and wholly 

 undesirable plants. The effect of age on the seed depends on 

 the condition of the seed when harvested, the manner of stor- 

 ing and keeping, and the character of the seed itself. In Cuba 

 the vitality of the seed is soon lost, especially when stored in 

 the ordinary manner by the Cuban farmers. In fact two or 

 three year old seed is of very doubtful value, in many cases 

 having entirely lost its vitality. This loss of power of germi- 

 nation in Cuban seed may be due to several reasons, and par- 

 ticularly to two main causes : first, the practice of sowing 

 sucker seed, and second, the moist atmosphere. The poor 

 quality of the seed, combined with the unfavorable climatic 

 conditions, tend to destroy the life of the seed very rapidly. 

 In any case it is the best plan to use fresh seed every year 

 when possible, and if necessary to use old seed a test of its 

 vitality should be made by sprouting several samples before 

 the seed is used for general sowing. 



SELECTION OF PLANTS IN THE SEED BED. 



One of the practical means of securing uniform crops in 

 the field is by the selection of plants in the seed bed at the 

 time of transplanting. At this early stage of growth the shape 

 of leaf, the comparative vigor of growth, and the general type 

 of the plants can be observed. If this matter is taken into con- 

 sideration, and the plants pulled by some one who is capable 

 of discarding the individuals of poor type, the benefit from this 

 kind of selection will be very marked and noticeable in the 

 crop in the field. It is supplementary to the selection of seed 

 plants, and, by combining both methods of selection, the rate 

 of improvement can be increased and improved types more 

 rapidly developed. 



STRAINS RESISTANT TO DISEASE. 



In a field of tobacco grown in the Connecticut valley in 1903 

 most of the plants were attacked and destroyed by a root 

 disease. A few of the plants in different sections of this field 



