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Inheritance of resistance of oat Iiybrids to loose and covered suntt 



The studies on the inheritance of smut resistance in oat hybrids 

 have been continued and a large amount of data has l)een ol^tained 

 with the second generation plants of several different crosses. 

 Since it is this generation of hybrids which regularly shows the 

 segregation of various characters, we may expect, in crosses in- 

 volving a resistant and susceptible variety, that some of the second 

 generation plants will prove to be resistant while others wnll be 

 susceptible. Additional data on this generation have been secured 

 with the hybrids Hull-less X Black IVIesdag, Early Gothland X 

 Victor, Fulghum X Black ]\Tesdag and Early Champion X Black 

 Mesdag, all of which have been previously reported upon. The 

 new data correspond rather closely with the results previously pub- 

 lished. Since relatively small numbers of plants were involved, 

 there were minor variations from the results previously obtained, 

 but no very wide departtu'es were noted. 



Perhaps the most interesting new combination involved a cross 

 between E;u-ly Gothland and Monarch. The former is very sus- 

 ceptible to the loose smut but resistant to the covered, while the 

 Monarch variety shows exactly the reverse behavior with reference 

 to the two smuts. A few second generation plants of a cross in- 

 volving these two varieties were grown, one set having been 

 inoculated with the loose smut and another with the covered smut. 

 The combined results for the loose smut with the reciprocal crosses 

 between the varieties gave 9 infected plants out of a total of 50 

 (18.0 i)er cent.), and for the covered smut 9 infected plants out 

 of a total of 85 (10.5 per cent.). The study of the third genera- 

 tion grown from the resistant individuals of these experiments as 

 well as from uninoculated second generation plants i^romises to 

 yield very interesting results. A large number of such third 

 generation ])lants are now being grown in the greenhouse and 

 additional ones will be planted in the field in 1930. 



A great many third generation progenies of various crosses 

 were grown during the past season. There were included 34 such 

 progenies of Early Gothland X Victor and 102 of h^arly Goth- 

 land X Hull-less. These were all inoculated with the covered 

 smut. Since one parent — Early Gothland — is resistant, while the 

 other parent — Hull-less in one cross and Victor in the other — is 

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