19-21.] Ini'I.urncf, ok Size of SnKn on Yiki.d ok Potatous. 



43 



THE INFLUENCE OF SIZE AND 

 CHARACTER OF SEED ON THE 

 YIELD OF POTATOES. 



Redcliffe N. Sai.aman, M.A., j\].D. 



In 1920 a preliminary investigation of the above problem was 

 begun. For this purpose a stock of a new variety* was 

 employed, which had been grown in Barley, Herts, the previous 

 year; the tubers had been clamped during the winter and 

 sprouted in the spring. This main crop variety is well adapted 

 to this type of experiment for two reasons : it is an exceptionally 

 heavy cropper and it is extremely resistant to leaf -roll and mosaic. 

 The tubers are white kidneys, and are immune to wart disease. 

 This stock was raised in 1911 by the writer in Barley. 



Selections of the seed tubers were made by the writer accord- 

 ing to various grades, and the number of tubers in every pound 

 weight of seed was carefully checked. The tubers were selected 

 both for size and weight so that each class was as uniform as 

 possible. 



The classes selected were : — 



Wei(//if of tuber nets. 



1. ' 0-4 oz. i.e., tubers to 1 Ih. 



2. i :^ „ 12 



2-0 „ ,. 8 



4. 2 () ,j „ G „ 



f>. 4- 4 „ „ „ 



(;. 5-3 „ „ 8 „ 



7. ;V0 „ ., 12 .. .. 4| lb. 



8. o-O „ „ 12 4^ „ 



9. Mixeil Heed ol" all sizes. 



Class No. 8 was not chosen with the idea of differentiating 

 the crop obtained from seed so very similar, both in size and 

 weight, to those used in Classes 6 and 7, but to discover whether 

 seed tubers which carried much secondary growth influenced 

 the resulting yield. In fact Class 8 differs merely as to the 

 pi-esence of secondary growth on all the seed tubers used, 

 from Classes 6 and 7. The tubers were planted in rows in the 

 midst of a farm crop of potatoes of the same variety. The part 

 of the field selected, the soil of which is a medium clayey loam, 

 is as nearly uniform in quality as it is possible to find in this 

 part of the country, and was chosen for that reason. Manuring 

 was the same for the entire potato crop, viz., 15 tons per acre 

 laid in the furrows on which tho potatoes were planted. The 



This potato is not. as yd. on the market. 



