III2 STARCH CROPS 



The comparative method adopted for determining the cooking quali- 

 ties and flavour of potatoes made it clear, as seen from Table II, that the 

 " Up to Date " variety was superior to the others, being the best for human 

 food, after which come the varieties Jubel, Imperator and Record, which 

 may be used for human food ; the sorts Bohm's Erfolg and Silesia, being 

 luisuitable for food purposes, must be classed among potatoes which can 

 be used for industrial objects. 



862 - Influence of Excess of Water in the Soil during the Second Half of the Summer, 

 on the Formation of Secondary Potato Tubers and their Starch Content. — arkhan- 



GELSKijM. in CeAbCKoe Xo3HUcmeo u JTioCoeodenieo (Agriculture and Sylviculture), 



Vol. CCIy, I^XXVlth Year, pp. 400-406. Petrograd, March 1916. 

 The formation of secondary tubers of the potato (excrescences of the 

 tuber) is a phenomenon which often occurs, according to Prof. Fruwirth, 

 in those years when excessive humidity of the soil follows a period of drought 

 at the moment when, in normal years, ripening of the tubers takes place. 

 Having observed this phenomenon in different varieties of potato, in his 

 experiments conducted in 1914 and 1915 at the agricultural experiment 

 Station of Tambov (Russia), the writer desired to clear up 2 further points of 

 the question : i) how does the formation of secondary tubers affect their 

 starch content ? — 2) how do the different varieties behave in reference 

 to the phenomenon studied, that is to say, what is the proportion of tubers 

 with secondary growths in the different varieties ? 



The tubers planted on 191 4 and 1915 were grown from varieties bought 

 in 1913 in one of the best known farms in the government of Riazan. The 

 following is a summary of the most important results of the experiments 

 carried out. 



I. — Influence of Humidity. — From the weather records it is evident 

 that during the first half of the summer, that is until the middle of July, 

 the rainfall and consequently the amount of moisture in the soil were normal 

 both in 1914 and 1915. On the 20th, 21st and 22nd July 1914 and the 14th 

 July 1915, however, there were such heavy falls of rain that they exceeded 

 the quantity which had fallen in 2 months in the previous years ; and others 

 followed, so much so that the moisture of the soil reached a very high degree. 

 After the crop it was found that the tubers of all the potatoes exhibited ex- 

 crescences from the body of the tuber. Such excrescences occurred in 

 two forms : i) a shrinkage occurred separating the oldest part of the tuber 

 covered with the rough skin from the newest part with a fine glossy and 

 easily detached skin ; 2) or a crop of secondarj^ tubers formed, small and 

 arranged in various wa5^s on the principal tuber, being very easily detached 

 therefrom. 



II. — Behaviour of the Different Varieties of Potatoes with regard to the 

 Excrescences. — A detailed analysis of the crop led to the conclusion that the 

 different varieties experimented on did not all produce the same proportion 

 of malformed tubers, i. e. tubers with excrescences. In order to determine 

 this difference more accurately, the percentage of malformed tubers for 

 each kind was calculated from their number in a given quantity of pot- 

 atoes. In 1915 these data were completed by al.so estimating the percentage 



