iN'. SALAMAN. ■- STl DIES IN l'OTATO DREEDING. 



575 



STUDIES IN POTATO BREEDING 



By Redcliffe N. SALAMAN M. D. 



liailey, ncar [ioy-lon llorls iKn^laml). 



In niv sanlen al Barley, in Herlfordshire, Englaml, I liave condiictcd 

 during Ihe lasl years, a séries of experimenls on Polatocs on Mondelian lines. 

 The results oblained during Ihe first i years hâve 

 already beon puljlished in detaiP. In the acconnt 

 I liavc Ihe pleasnre to suhmit lo liiis Conférence I 

 propose to give a résumé of Ihosc resnlls and of 

 those which havc occurred since. 



Tlie Shape of Tubcrit. — The varions shapes — 

 kidney, oval, lapstone and round, of Ihe seedsman's 

 catalogue are found to dépend essenlially on Ihe 

 présence or absence of one cliaracter, viz — tlial 

 for lenglh. Tubers are thus pure lony, heterozy- 

 goiis Idnij or round. The firsl and iast fornis are 

 inire and seed therefrom Ijreeds Irue to type. The 

 long potato is one in which 12 or more internodal 

 ienglhs — as evidenced by the number of eyes — 

 are condensed in the tuber. The actual shape may 

 lie cylindrical. pyriform or ki<lney. The round 

 lubcr i. e. the tuber pvu'e to the absence of Iciuil/i ,, , ''''"'' ' "' " ' 



M. Sm.amav. 



is one composed of from C to 9 nodal lenghts, ils 



shape resembles that of an apple, and is generally shorter in its vertical thnn 

 ils Iransverse diameter. The pure round potato is subject to slight variation 

 in the length of the vertical axis and may approach the oval type of Ihe seeds- 

 man, jjut, in gênerai, il is uniform and very characteristic. The long tuber is 

 dominant, and the hétérozygote is generally of kidney shape though such 

 shapes as lapstone and oval are also helerozygous as to length. 



One featiire of helerozygous plants is that the tubers borne by Ihcm are 

 variable, i. e. on one and the sanie stem-system longs such as kidnpys and more 

 or less pure rounds do occur. This has been observed frequcnlly. Aloreover, 

 if a large batch be raised from helerozygous kidney seed-tubers, then il is 

 common lo find in the resulting crop greal variation in the tuber shape, far 

 greater Ihan if the culture wcre from a pure homozygous stock. The variabilily 

 in many commercial kidney varieties when grown on a large scale is I think, lo 

 be altributed to their heterozygosis as regards the character for lenglh. 



Tlie Tuber Eyes. ■ — The eyes of the polafo tuber are described as deep or 

 as sifperprial. Those which bear tubers ail with deeply incised eyes will breed 

 !)y seed pure lo dopth. Similarly the snperficial or fleet eyed potato breeds 

 Irue. The hybrid is poculiar in as much as there is no complète dominance, 

 Ihe hybrid tuber howovcr,can moreoften be described aspossessing suporflcial 



1. Communication failc à la troisième ?éanco do l.i ConlV'ipnco. 



2. Jmmial nf Geiietics. vol 1, îio. 1, S Nov. 1!ll(l. 

 I.iiiiirnn Soi;rly\Jouninl. liol.iny. vnl. NNXIX, 0,1. 1910. 



