Dec. 1894.] EXPERIMENTS IN PLANTING POTATOES. 



179 



From the mean of the total yields of the different varieties 

 dealt with in the experiments of 1891, 1892, and 1893, as 

 well as from the mean of the total number of cases in which the 

 seed failed to germinate, the following table has been drawn up 

 showing the proportions both of the yield of potatoes and of the 

 per-centage of failure in respect of each of the six methods of 

 j)lanting : — 





Per-centage. 



Weight of Seed. 









Weight of 



Number of 





Crop. 



Failures. 



Tubers of 3| oz. planted whole 



100 



6 



„ „ cut iLto two portions 



69-3G 



12 



„ 7 oz. two „ - - 



82 



10-.5 



„ 10| oz, ., three „ 



74 



14-5 



„ If oz. Two tubers planted together 



95-36 



3-7 



„ 1 oz, Three „ '„ 



>'912 



3-7 



M. Girard points out that on comparing these mean figures 

 Avith the particular figures relating to each variety, the difference 

 between th(i former and the extreme figures are so slight that 

 the mean may be regarded as conveying in this instance a very 

 fair idea of the actual facts. 



He thinks, therefore, that the experiments have shown that — 



1. The maximum crop is obtained by planting entire tubers of 

 medium weight. 



2. The crop is diminished about 30 per cent, if such tubers are 

 cut into two portions. 



3. The crop is diminished, with rare exceptions, about 20 per 

 cent, by planting cut seed weighing 3J ozs. from whole tubers 

 weighing 7 ozs. or lOJ ozs. 



4. If two or three small tubers, weighing in all 3^ ozs., are 

 planted together, the crop is on the average from 5 to 10 per 

 cent, less than that obtained by planting whole tubers of medium 

 weight. 



According tj M. Girard, it would, however, be a mistake to 

 assume that these latter proportions are anything more than 

 approximate. For the crop obtained from small tubers is in 

 some cases 25 to 30 per cent, inferior to that obtain;^d from 

 medium-sized tubers, as was shown by the Gelbe Rose crop in 

 1892, and the Athens in 1893. On the other hand, it appears 

 that under certain circumstances, especially during a dry season, 

 the planting of small seed tubers may produce J 5 to 20 per cent, 

 more than the larger single tuber. 



The results just stated might also have been deduced from the 

 per-centage of failures of each of the different systems of pi 'Uting. 

 In the case of cut tubers this proportion varied from 12 to 15 

 per cent. ; for tubers of medium size it was only 6 per cent. ; 

 while for small tubers the proportion of failures was less than 

 4 per cent. 



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