NOTES AND ABSTRACTS. 



137 



Potato, Improvement of the. By Edward M. East (U.S.A. Exp. 

 Stn., Illinois, Bull. 127, pp. 375-456). — The author considers that 

 promising strains may perhaps be isolated from S. Commersonii, but not 

 from any of the other wild species of potato. Even Commerson's 

 potato has so far not proved satisfactory in the United States. After 

 a short discussion of the historical facts dealing with the introduction 

 of the potato into Europe he points out that certain varieties do not 

 produce flowers or else have infertile pollen which makes the introduction 

 of new strains by crossing or raising from true seeds a difficult and 

 uncertain process. Ninety per cent, of the modern United States crop is 

 from varieties which have been produced by scientific breeders such as 

 the late E. S. Carman. The differences in yield of these varieties is very 

 great, varying from 18*7 (' E. Six Weeks ') to 137*7 bushels (' Green 

 Mountain ') of marketable tubers per acre. The yield is in proportion to 

 the growing season, provided that there is entire maturity before frost. 

 In general, luxuriant vegetation is a sign of great productiveness, but in 

 some varieties excessive vegetative growth is opposed to tuber formation. 

 Rapid growth at first increases the yield, which is affected also by the 

 weight of the seed-piece, by the amount of sunlight (darkened glass, clear 

 glass, and open air as 1 : 5: 11), by differences of age and of vigour in 

 eyes when sprouted before planting, and by depth of planting. Drying 

 the seed tubers, up to a loss of 20 per cent, moisture, also increases 

 the yield. 



The author summarizes a large number of experiments dealing with 

 the inheritance of characters when tubers are specially selected. Many 

 of these experiments did not result in definite conclusions, for seasonal, 

 climatic, and local soil conditions have "a tremendous effect." 



It is, however, quite clear that tubers of a plant which has a large 

 yield tend to be extremely productive. Thus in one variety large seed 

 tubers of a productive mother plant gave a crop of 319 g. Small seed 

 tubers of the same plant gave 220 g., whilst large and small 

 seed tubers of a small-yielding mother plant gave 113*3 g. and 80*9 g. 

 respectively. 



The author also discusses the question of degeneration in potato 

 varieties, and considers that there is no " old age" degeneracy, but 

 that disease control is the most important point to consider. 



The quality of potatos for table use depends upon the anatomical 

 structure. A thick cortical layer and small number of eyes are of 

 advantage. Variations in table quality may be inherited, and can be 

 used for the formation of new Varieties. There are also variations in 

 quality within one strain which are produced by the particular 

 conditions under which the potatos have been grown. 



In composition (total nitrogenous matter) there is a surprising 

 variability within one particular variety. Smaller, younger tubers are 

 richer in nitrogen ; but particular shapes or the number of eyes do not 

 give any information as to the nitrogen content. Specific gravity tables 

 are unsafe for the determination of the amount of starch. One tuber 

 with specific gravity 1*090 contained 14*32 per cent, nitrogenous 

 matter. Another (1*091 specific gravity) had only 7*39 per cent. 



There are also experimental results with regard to high protein 



